KYMCO MXU 550i 2021 Repair Manual
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KYMCO MXU 550i 2021 Repair Manual

KYMCO MXU 550i 2021 Repair Manual

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KYMCO Repair Manual
MXU 550i
KYMCO MXU 550i Service Information
Models Covered:
2021 KYMCO MXU 550i
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Summary of Contents for KYMCO MXU 550i 2021

  • Page 1 KYMCO Repair Manual MXU 550i KYMCO MXU 550i Service Information Models Covered: 2021 KYMCO MXU 550i...

  • Page 2: Using This Manual

    Always read a procedure in its entirety before attempting any repairs. Many thumbnail images can be clicked on to show larger images. Topics that are explained in greater detail are referenced and linked to. This manual features a 2021 KYMCO MXU 550i engine chapter.

  • Page 3: Table Of Contents

    1.Quick Reference MXU 550i Quick Reference This chapter provides a quick reference source of technical specifications and information for the KYMCO MXU 550i models. Break In Procedure ..................... 2 General Information ....................3 VIN and Engine Number Location ................24 Special Tools ......................

  • Page 4: Break In Procedure

    1.Quick Reference MXU 550i Break In Procedure A new ATV and an overhauled ATV engine require a "break-in" period. The first 10 hours (or 200 miles) are most critical to the life of this ATV. Proper operation during this break-in period will help assure maximum life and performance from the ATV.

  • Page 5: General Information

    1.Quick Reference MXU 550i General Information Break In Procedure A new ATV and an overhauled ATV engine require a "break-in" period. The first 10 hours (or 200 miles) are most critical to the life of this ATV. Proper operation during this break-in period will help assure maximum life and performance from the ATV.

  • Page 6: Recommended Oil

    1.Quick Reference MXU 550i FILLING THE GAS TANK WARNING: Always fill the gas tank in a well-ventilated area Never add fuel to the ATV gas tank near any open flames or with the engine running. DO NOT SMOKE while filling the gas tank.

  • Page 7: Genuine Parts

    3. Either drain the gas tank or add Fuel Stabilizer to the gas in the gas tank. Remove the air filter housing cover and air filter. Start the engine and allow it to idle; then using KYMCO Engine Storage Preserver, rapidly inject the preserver into the air filter opening for a period...

  • Page 8: Preparation After Storage

    Preparation After Storage Taking the ATV out of storage and correctly preparing it will assure many miles and hours of trouble-free riding. KYMCO recommends the following procedure to prepare the ATV. 1. Clean the ATV thoroughly. 2. Clean the engine. Remove the cloth from the muffler.
  • Page 9 1.Quick Reference MXU 550i Caution: The ignition switch must be in the OFF position prior to installing the battery or damage may occur to the ignition system. Connect the positive battery cable first, then the negative. 6. Check the entire brake systems (fluid level, pads, etc.), all controls, lights, and headlight aim;...
  • Page 10 1.Quick Reference MXU 550i When tightening bolts or nuts, begin with larger-diameter and move to smaller ones. Tighten bolts evenly and tighten to the specified torque diagonally. Use genuine parts and lubricants.
  • Page 11 1.Quick Reference MXU 550i When servicing the motorcycle, be sure to use the indicated special tools for removal and installation. After disassembly, clean and inspect the removed parts. Lubricate sliding surfaces with engine oil before reassembly.
  • Page 12 1.Quick Reference MXU 550i Apply or add designated greases and lubricants to the specified lubrication points. After reassembly, check all parts for proper tightening and operation. 1-10...
  • Page 13 1.Quick Reference MXU 550i When two persons work together, pay attention to the mutual working safety. Disconnect the battery negative (-) terminal before working on the vehicle. When using a spanner or other tools, make sure not to damage the motorcycle surface. 1-11...
  • Page 14 1.Quick Reference MXU 550i After working on the vehicle, check all connecting points, fasteners, and lines for proper connection and installation. When connecting the battery, the positive (+) terminal must be connected first. After connection, apply grease to the battery terminals. Terminal caps must be installed securely.
  • Page 15 1.Quick Reference MXU 550i After working on the vehicle make sure terminal caps shall have been installed securely. Disengage the lock on locking electrical connectors before attempting to unplug them. 1-13...
  • Page 16 1.Quick Reference MXU 550i Hold the connector body when connecting or disconnecting it. Do not pull the connector wire. Check for faulty connector terminals. There shouldn't be any bent, protruding or loose terminals. Make sure the connector is plugged in completely. Make sure the connector locks correctly if a lock is present.
  • Page 17 1.Quick Reference MXU 550i Before connecting an electrical connector, check for damaged terminal cover or loose negative terminal. Check the bullet connector cover for proper coverage and installation. Join the terminals completely in bullet connectors. Check the cover for proper coverage. Do not make the cover opening face up.
  • Page 18 1.Quick Reference MXU 550i Secure wire harnesses to the frame with the respective wire bands at the designated locations. Tighten the bands so that only the insulated surfaces contact the wire harnesses. After clamping, check each wire to make sure it is secure. 1-16...
  • Page 19 1.Quick Reference MXU 550i Do not squeeze wires against the weld or its clamp. After clamping, check each harness to make sure that it is not interfering with any moving or sliding parts. 1-17...
  • Page 20 1.Quick Reference MXU 550i Secure the wire harness so that it will not make contact with parts which will generate high heat. Route wire harnesses to avoid sharp edges or corners. Avoid the projected ends of bolts and screws. Route wire harnesses passing through the side of bolts and screws. 1-18...
  • Page 21 1.Quick Reference MXU 550i Route harnesses so they are neither pulled tight nor have excessive slack. Protect wires and harnesses with electrical tape or tube if they contact a sharp edge or corner. 1-19...
  • Page 22 1.Quick Reference MXU 550i Make sure rubber wire grommets are installed correctly. Do not break the sheath of wire. If a wire or harness has a broken sheath, repair it by wrapping it with protective tape or replace it if needed. 1-20...
  • Page 23 1.Quick Reference MXU 550i When installing other parts, do not press or squeeze the wires. After routing, check that the wire harnesses are not twisted or kinked. 1-21...
  • Page 24 1.Quick Reference MXU 550i Wire harnesses routed along with handlebar should not be pulled tight, have excessive slack or interfere with adjacent or surrounding parts in all steering positions. When a testing device is used, make sure to understand the operating methods thoroughly and operate according to the operating instructions.
  • Page 25 1.Quick Reference MXU 550i Be careful not to drop any parts. When rust is found on a terminal, remove the rust with sand paper or equivalent before connecting. 1-23...

  • Page 26: Vin And Engine Number Location

    1.Quick Reference MXU 550i VIN and Engine Number Location The VIN stamped into the front of the frame just in front of the front differential. The engine number is located near the bottom of the left crankcase half. 1-24...

  • Page 27: Special Tools

    1.Quick Reference MXU 550i Special Tools Tool Name Tool No. Oil seal and bearing installer A120E00014 Valve adjuster A120E00080 Bearing puller A120E00037 Valve spring compressor A120E00040 Universal holder A120E00056 Drive pulley holder A120E00058 Tool Name Tool No. Clutch Spring Compressor Fittings 46mm HEX A120E00057 Flywheel puller A120E00060...

  • Page 28: Specifications

    1.Quick Reference MXU 550i Specifications General Specifications Model No. MXU 550i LEA0LA Overall length 2140 mm Overall width 1245 mm Overall height 1250 mm Wheel base 1297 mm Engine type 4 stroke D.O.H.C. Displacement 498.5 cc Fuel used 92# nonleaded gasoline Front wheel 170 kg Dry weight...
  • Page 29 2.6 L (oil and filter change) 2.9 L (total) Air cleaner type & No Wet type element Fuel capacity 21 L TYPE KYMCO PTA1 Throttle body VENTURE DIA 38 mm Type Full transistor digital ignition 5° at idle rpm (MXU 500i) Ignition timing 10°...

  • Page 30: Lubrication Specifications

    Dual A-Arm Suspension type Rear Dual A-Arm Lubrication Specifications ITEM STANDARD SERVICE LIMIT Recommended engine KYMCO 4-stroke oil or equivalent motor oil API service — classification SJ Viscosity: SAE 5W-50 0.15 max clearance Oil pump Body 0.15 - 0.2 0.25...
  • Page 31 1.Quick Reference MXU 550i At disassembly: 270 cc At change: 250 cc Rear gear box oil Recommended oil: SAE 80 At disassembly: 250 cc At change: 230 cc Fuel Injection Specifications ITEM SPECIFICATIONS Throttle body identification number PTA1 Throttle cable free play 3 ~ 5 mm Fuel injector resistance (at 20°C/68°F) 10.6 - 15.9 Ω...
  • Page 32 1.Quick Reference MXU 550i Engine Specifications MXU 500i Engine Item Standard mm (in) Service Limit 0.1 mm (0.004 in) Valve clearance (cold) 0.1 mm (0.004 in) Cylinder head compression pressure 15 kg/cm (1500 kPa, 213 psi) Cylinder head warpage 0.05 (0.002) Camshaft runout 0.05 (0.002) 37.2614 (1.4905)
  • Page 33 1.Quick Reference MXU 550i Second 0.03 - 0.45 (0.012 - 0.018) 0.65 (0.026) Oil side 0.2 - 0.7(0.008 - 0.028) 1 (0.04) rail Piston O.D. 91.96 - 91.98 (3.6784 - 3.6793) 91.9 (3.676) Piston O.D. measuring position 10 mm from bottom of skirt Piston-to-cylinder clearance 0.01 - 0.045 (0.0004 - 0.0018) 0.1 (0.004)

  • Page 34: Cooling System Specifications

    1.Quick Reference MXU 550i Cooling System Specifications ITEM SPECIFICATIONS 2.4 liter, 2.54 US qt. (MXU700i) Radiator and engine 1.95 liter, 2.06 US qt. (MXU500i) Coolant capacity Reserve tank 0.3 liter, 0.32 US qt. Radiator cap relief pressure 90 kPa (0.9 kgf/cm , 12.8 psi) Begin to open 69 - 73°C (156 - 163°F)
  • Page 35 1.Quick Reference MXU 550i Wheel and Brake Specifications Item Standard Service Limit Radial — 2 mm (0.08 in) Wheel rim run out Axial — 2 mm (0.08 in) Toe in 0~15 mm (0~0.59 in) — Item Standard mm (in) Service Limit Brake disk thickness FR: 4.0 (0.156) RR: 5.0 (0.195) FR: 3 (0.12) RR: 4 (0.156)
  • Page 36 1.Quick Reference MXU 550i Spark Pug Type NGK CR7E Spark Plug Cap 4000-6000 ohms Ignition Coil Resistance (primary) Less than 1 ohm (terminal to terminal) Ignition Coil (primary/CDI) Peak Voltage 250-375 DC volts (black/yellow to black) Crank Position Sensor Resistance 90-110 ohms (green/white to blue/yellow) Stator Coil Resistance Less than 1 ohm (yellow to yellow)

  • Page 37: Torque Specifications

    1.Quick Reference MXU 550i Torque Specifications If a specific torque spec is not given consult the General Torque Specifications. MXU550i Torque Specs Torque Item Q'ty Thread dia. (mm) Remarks kgf-m (N-m, ft-lb) MAINTENANCE: Spark plug 1.2 (12, 8.6) Tappet ADJ nut 0.9 (9, 6.5) Engine oil filter cap 1.5 (15, 11)
  • Page 38 1.Quick Reference MXU 550i Water joint bolt 1.2 (12, 8.6) CYLINDER: Cylinder bolt 1 (10, 7.2) DRIVE/DRIVEN PULLEY: Drive pulley nut 14 (140, 100.8) Apply oil Wet clutch nut 14 (140, 100.8) Driven pulley nut 10 (100, 72) Apply oil Driven pulley assembly plate nut 7.5 (75, 54) TRANSMISSION:...
  • Page 39 1.Quick Reference MXU 550i Exhaust pipe mounting nut 3.5 (35, 25) Exhaust muffler band bolt 2.1 (21, 15) ENGINE ASSEMBLY: Engine mounting bolt/nut 6 (60, 43.5) Engine hanger nut 3.5 (35, 25) DRIVE TRAIN: Front drive: Front propeller shaft bolt 4.5 (45, 32.4) Front drive gear case mounting Apply threebond:...
  • Page 40 1.Quick Reference MXU 550i Front/rear wheel and hub 6.1 (61, 44) Front wheel hub and front halfshaft(CVJ) 28 (280, 202) Castle nut Rear wheel hub and rear halfshaft(CVJ) 28 (280, 202) Castle nut Front wheel hub and stud axle(2WD only) 28 (280, 202) Castle nut SUSPENSION:...
  • Page 41 1.Quick Reference MXU 550i Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Front caliper and knuckle 2.7 (27, 19) Rear caliper and bracket 2.7 (27, 19) Master cylinder cap screw 0.15 (1.5, 1.1) Brake caliper bleed valve 0.55 (5.5, 4.0) Brake pedal adjusting nut 0.9 (9, 6.5) Rear disc holder and gear box...
  • Page 42 1.Quick Reference MXU 550i BOLT M8 x 1.25 10.8± 0.1 8 APPLY OIL NUT M8 x 1.25 24.5± 1 .2 18 APPLY OIL ROCKER COVER M6 x 1.0 SPARK PLUG M10 x 1.0 9.8-13.7 7.2-10.1 TAPPET ADJ. NUT M5 x 0.5 6.9-10.8 5.1-7.9 TENSIONER LIFTER...

  • Page 43: General Torque Specifications

    1.Quick Reference MXU 550i General Torque Specifications General torque specifications are only to be used when specific torque specifications for a fastener are not provided. These specifications are for clean unlubricated threads. The size given is for thread diameter not bolt head size. Torque Item kgf-m...

  • Page 44: Troubleshooting

    1.Quick Reference MXU 550i Troubleshooting Engine and Fuel System Troubleshooting Problem: Engine will not start or is hard to start (Compression too low) Condition Remedy 1. Valve clearance out of adjustment 1. Adjust clearance 2. Valve guides worn 2. Replace cylinder head 3.
  • Page 45 1.Quick Reference MXU 550i 4. Valve clearance out of adjustment 4. Adjust clearance 5. ECU unit defective 5. Replace ECU Problem: Engine noisy (Excessive valve chatter) Condition Remedy 1. Valve clearance too large 1. Adjust clearance 2. Valve spring(s) weak - broken 2.
  • Page 46 1.Quick Reference MXU 550i Problem: Engine noisy (Noise seems to come from secondary bevel gear and final driven shaft) Condition Remedy 1. Drive or driven bevel gears damaged or worn 1. Replace gears 2. Backlash excessive 2. Adjust backlash 3. Tooth contact improper 3.
  • Page 47 1.Quick Reference MXU 550i 9. Fuel hose obstructed 9. Clean or replace hose 10. Fuel pump defective 10. Replace fuel pump Problem: Exhaust smoke dirty or heavy Condition Remedy 1. Oil (in the engine) overfilled - contaminated 1. Drain excess oil - replace oil 2.

  • Page 48: Electrical Troubleshooting

    1.Quick Reference MXU 550i 7. Intake manifold leaking air 7. Tighten - replace manifold 8. Fan malfunctioning 8. Check fan fuse - replace fan 9. Fan switch malfunctioning 9. Replace fan switch Final Drive Troubleshooting Problem: Engine power not transmitted to wheels Condition Remedy 1.
  • Page 49 1.Quick Reference MXU 550i 5. Oil rings worn - broken 5. Replace rings Problem: Spark plug electrodes overheat or burn Condition Remedy 1. Spark plug incorrect (too hot) 1. Replace plug 2. Engine overheats 2. Service cooling system 3. Spark plug loose 3.

  • Page 50: Brake Troubleshooting

    1.Quick Reference MXU 550i 4. Starter relay defective 4. Replace relay 5. Emergency stop - ignition switch off 5. Turn on switches 6. Wiring connections loose - 6. Connect - tighten - repair connections disconnected Problem: Battery "sulfation" (Acidic white powdery substance or spots on surfaces of cell plates) Condition Remedy 1.

  • Page 51: Suspension And Steering

    1.Quick Reference MXU 550i Problem: Brake fluid leaking Condition Remedy 1. Connection joints loose 1. Tighten joint 2. Hose cracked 2. Replace hose 3. Piston seal worn 3. Replace brake caliper Suspension and Steering Problem: Suspension too soft Condition Remedy 1.
  • Page 52 1.Quick Reference MXU 550i 2. Lubrication inadequate 2. Lubricate appropriate components 3. Tire inflation pressure low 3. Adjust pressure 4. Tie rod ends seizing 4. Replace tie rod ends 5. Linkage connections seizing 5. Repair - replace connections Problem: Steering oscillation Condition Remedy 1.

  • Page 53: Diagnostic Trouble Codes (Dtcs)

    1.Quick Reference MXU 550i Diagnostic Trouble Codes (DTCs) To evaluate the DTCs see the Check Engine Lamp (CELP) Diagnostic Tool topics. Failure Blinks Fault description Priority Fault management Codes 1.Stop immediately and check CELP code. 2. Check if the engine temperature sensor or Engine temperature electric circuit is faulty.
  • Page 54 1.Quick Reference MXU 550i 1.Check the ISC steps range with the diagnostic tool. Idle speed volume control P0505 2. Check throttle body for carbon range problem deposits. 3. Check intake for air leaks 1. Make sure the fuel injector connector is connected correctly.
  • Page 55 1.Quick Reference MXU 550i 1. Make sure the WTS connector is connected Engine temperature correctly. P0115 sensor or electric circuit 2. Check if the ECU pin is broken. malfunction 3. Check if the resistance of the sensor is out of specification.

  • Page 56: Periodic Maintenance

    Periodic Maintenance This chapter covers the location and servicing of the periodic maintenance items for the KYMCO MXU 550i models. This chapter includes all information necessary to perform recommended inspections and adjustments. These preventive maintenance procedures, if followed, will ensure more reliable vehicle operation and a longer service life.

  • Page 57: Periodic Maintenance Chart

    2.Periodic Maintenance MXU 550i Periodic Maintenance Chart Periodic maintenance is required to keep the vehicle safe and performing properly. For use exceeding the chart repeat the service intervals. INITIAL EVERY WHICHEVER COMES FIRST 600 1200 ITEM 1000 2000 ROUTINE MONTH 1 Engine oil •Replace (Warm engine before draining).
  • Page 58 2.Periodic Maintenance MXU 550i •Check valve clearance, Valves •Adjust if necessary. •Check operation and brake fluid. Brake •Replace brake pad if necessary. •Check coolant leakage. Coolant •Replace if necessary. •Replace coolant every 24 months. •Check operation. V-belt •Replace if damage or excessive wear. •Check leakage.

  • Page 59: Air Filter Servicing

    2.Periodic Maintenance MXU 550i Air Filter Servicing SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Cover Remove the seat. See the Seat topic for more information. The air filter housing cover is held in place by six latches. Unlock the air filter cover latches.
  • Page 60 2.Periodic Maintenance MXU 550i Remove the air filter housing cover. Inspect the air filter housing cover rubber seal and replace it as needed. Loosen the air filter clamp screw with a flat blade screwdriver or an 8 mm socket. Lift out the air filter.
  • Page 61 2.Periodic Maintenance MXU 550i Loosen the air filter holder screw with a #2 Phillips screwdriver. Remove the screw and washers from the air filter. Remove the air filter holders from the air filter. Slide out the air filter screen.
  • Page 62 2.Periodic Maintenance MXU 550i Separate the inner and outer air filter element pieces. Servicing Place the filter in a container and saturate it with a foam air filter cleaner both inside and out. Products like Simple Green, dish soap, or most non-flammable solvents will work if foam air filter cleaner is unavailable.
  • Page 63 2.Periodic Maintenance MXU 550i Let the filter soak for approximately 5 minutes - follow cleaning product instructions if different. Rinse the element in warm water until the water runs clear. You may squeeze the filter to remove excess cleaner but never twist it. Let the air filter dry completely.

  • Page 64: Installation

    2.Periodic Maintenance MXU 550i Installation Fit the inner air filter element into the outer element. Insert the screen into the air filter elements.
  • Page 65 2.Periodic Maintenance MXU 550i Install the air filter holders into the air filter. The holders must fit together as shown. Install the air filter holder screw and washers. Tighten the air filter holder screw securely with a #2 Phillips screwdriver. 2-10...
  • Page 66 2.Periodic Maintenance MXU 550i Fit the air filter into place. Tighten the air filter clamp screw securely with a flat blade screwdriver or an 8 mm socket. Cover Fit the airbox cover into place. Make sure the rubber seal is installed and in good condition. 2-11...

  • Page 67: Airbox Drain

    2.Periodic Maintenance MXU 550i Secure the air filter cover latches. Airbox Drain Inspect the airbox drain tube. 2-12...
  • Page 68 2.Periodic Maintenance MXU 550i Remove the tube and drain away any fluid build up or debris that has collected. Return the tube and secure it with the clamp. 2-13...

  • Page 69: Brake Fluid

    MXU 550i Brake Fluid The KYMCO MXU 550i models uses DOT 4 brake fluid. Do not mix the brake fluid types. The system should be bled whenever the brakes feel spongy, or if the brake system has been taken apart and rebuilt. Always use fresh brake fluid from a tightly sealed container.
  • Page 70 2.Periodic Maintenance MXU 550i Bleeder Valves There is a bleeder valve on each brake caliper. 2-15...
  • Page 71 2.Periodic Maintenance MXU 550i The bleeder valves are usually very tight so use a box end wrench or a 6 point socket and ratchet to prevent rounding off the head. Snug the bleeder valve back down after breaking it loose the first time. Place the box end wrench on the valve and attach a clear hose to the bleeder valve for draining or bleeding.
  • Page 72 2.Periodic Maintenance MXU 550i Draining To remove the brake fluid remove the reservoir cap, open the bleeder valve and suck out he old brake fluid with a mighty-vac or similar devise. Bleeding There are three separate brake systems, one with each master cylinder. Master Cylinder Caliper/s Right Handlebar...
  • Page 73 2.Periodic Maintenance MXU 550i A. Remove the cover and fill the reservoir with DOT 4 brake fluid from a fresh, newly opened container and bleed the brakes. B. Install the cover to keep debris out of the fluid: then slowly compress the brake lever (or pedal) several times.
  • Page 74 2.Periodic Maintenance MXU 550i C. Remove the protective cap. Install one end of a clear hose onto the bleeder screw of the brake system being serviced, and direct the other end into a container: then while holding pressure on the brake lever, open the bleeder screw and watch for air bubbles. Close the bleeder screw before releasing the brake lever.

  • Page 75: Brake Inspection

    2.Periodic Maintenance MXU 550i Brake Inspection SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Master Cylinder Place the vehicle on level ground so the master cylinder reservoirs are level. Check the level of brake fluid. The brake fluid level should be above the "L" line. Remove the rear fender to view the rear brake master cylinder reservoir.

  • Page 76: Brake Pads

    2.Periodic Maintenance MXU 550i Note: The more the brake pads are worn the more fluid will be required from the reservoir to fill out the system. If the brake fluid is filled with worn pads, and new pads are installed the brake fluid level in the reservoir will rise.

  • Page 77: Brake Discs

    2.Periodic Maintenance MXU 550i Brake Discs Inspect the brake disc for damage. See the Brake Discs topic for more information. Rear Brake Pedal Height Remove the right mudguard. See the Mudguards and Footrests topic for more information. To adjust the rear brake pedal height loosen the locknut and turn the adjuster bolt. Tighten the locknut securely when finished.

  • Page 78: Rear Brake Light Switch

    2.Periodic Maintenance MXU 550i Rear Brake Light Switch The rear brake light switch should trigger the brake light just before the rear brake engages. Hold the switch body still and turn the nut to adjust the rear brake light switch if needed. 2-23...

  • Page 79: Compression Check

    2.Periodic Maintenance MXU 550i Compression Check SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Run the engine to warm it up before conducting a compression test. Make sure your compression gauge is in good working order and does not leak. The battery must be fully charged when testing the compression.
  • Page 80 2.Periodic Maintenance MXU 550i Hold the throttle wide open and use the electric starter to turn the engine over. Crank the engine until the needle on your compression gauge stops rising. This should occur in 4 to 7 seconds of engine cranking. Do not crank the engine for more than 7 seconds. Compare your reading with the specification.

  • Page 81: Engine Idle Speed

    2.Periodic Maintenance MXU 550i Engine Idle Speed SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Start the engine and let it warm up. The engine must reach 80° C to correctly inspect the idle speed. Connect the diagnostic tool and use the DATA analyze feature to inspect the idle speed. See the Diagnostic Tool topic for more information.

  • Page 82: Engine Oil

    SERVICE ITEM STANDARD LIMIT Recommended KYMCO 4-stroke oil or equivalent motor oil API — engine oil service classification SJ Viscosity: SAE 5W-50 Other engine oil viscosities shown in the chart may be used when the average temperature in the riding area is within the indicated range.
  • Page 83 2.Periodic Maintenance MXU 550i Inspection Start the engine and let it warm up for 2 - 3 minutes. Park the vehicle on a level surface. Stop the engine and allow the oil to settle for at least a minute. The oil sight glass is located on the right side of the vehicle. Peak behind the footrest mudguard to see the oil sight glass and oil filler cap.
  • Page 84 2.Periodic Maintenance MXU 550i Inspect the oil level through the sight glass. The sight glass is located on the left side of the engine. The oil level should be between the "H" and "L" marks as shown. If the oil level is at or below the "L" mark add more of the same type and brand of oil to the engine through the oil filler hole.
  • Page 85 2.Periodic Maintenance MXU 550i Servicing To replace the oil filter cartridge remove the right side cover. See the Side Covers topic for more information. Start and run the engine for a minute or two, this will heat the engine and allow the oil to drain out faster and more completely.
  • Page 86 2.Periodic Maintenance MXU 550i Loosen the oil filter cap with a 19 mm socket. Remove the drain plug, oil filter cap, strainer, spring and O-ring. Allow the oil to drain into the pan. Clean and inspect the strainer. Inspect the O-ring. Replace any parts if needed. Note: You can remove the drain plug to drain the engine oil also, but you will not be able to clean the strainer.
  • Page 87 2.Periodic Maintenance MXU 550i Remove the oil cap for faster draining. Use an oil filter wrench and loosen the oil filter cartridge. Special Tool - Oil Filter Wrench: A120E00052 2-32...
  • Page 88 2.Periodic Maintenance MXU 550i Remove the oil filter cartridge. Apply engine oil to the O-ring. When the oil has finished draining install the oil filter cap, strainer, spring and O-ring. Torque the oil filter cap to specification with a 17 mm socket. Torque Item Q'ty Thread dia.
  • Page 89 2.Periodic Maintenance MXU 550i Apply fresh engine oil to the rubber oil filter cartridge seal. Install the oil filter cartridge onto the engine and tighten by hand until the oil filter contacts the engine. 2-34...
  • Page 90 2.Periodic Maintenance MXU 550i Tighten the oil filter cartridge to specification with the oil filter wrench. Torque Item Q'ty Thread dia. (mm) Remarks kgf-m (N-m, ft-lb) Engine oil filter cartridge 1 (10, 7.2) Apply oil Refilling Oil total capacity MXU 500i 3.6 L Oil exchanging capacity MXU 500i 3.0 L...
  • Page 91 2.Periodic Maintenance MXU 550i Add the proper type and quantity of oil and install the oil filler cap. Start the engine and let it run for several minutes. Check for any oil leaks. Check the oil level as describe above. If the oil level is too high drain the excess oil from the oil drain bolt.

  • Page 92: Final Drive Oil

    2.Periodic Maintenance MXU 550i Final Drive Oil SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Front gear box oil Recommended oil: SAE 80 At disassembly: 270 cc At change: 250 cc Rear gear box oil Recommended oil: SAE 80 At disassembly: 250 cc...
  • Page 93 2.Periodic Maintenance MXU 550i Remove the oil level check bolt with an 8 mm socket. If oil doesn't flow from the check hole add oil until it reaches the level of the check hole. Return the check bolt to the hole and tighten it securely with an 8 mm socket.
  • Page 94 2.Periodic Maintenance MXU 550i The drain bolt (D) is located on the right side of the front final drive gear case. Place a suitable oil drain pan under the drain bolt. Remove the drain bolt with an 8 mm socket. Allow the gear oil to drain into the drain pan. Install the drain plug and tighten it to specification with an 8 mm socket.
  • Page 95 2.Periodic Maintenance MXU 550i Filling Front gear box oil Recommended oil: SAE 80 At disassembly: 270 cc At change: 250 cc Remove the filler cap with a 17 mm socket. Inspect the filler cap O-ring and replace it as needed. Remove the check level bolt.
  • Page 96 2.Periodic Maintenance MXU 550i Install the check bolt and filler cap and tighten them to specification. Torque Item Q'ty Thread dia. (mm) Kgf-m (N-m, ft-lb) Front drive gear oil filler cap 3.5 (35 25.5) Front drive gear oil level check bolt 1 1 (10, 7.2) 2-41...
  • Page 97 2.Periodic Maintenance MXU 550i Rear Final Drive Gear Oil Inspection The filler cap (F), check bolt (C), and drain bolt (D) are all located on the left side of the rear final drive gear case. Remove the oil level check bolt with a 12 mm socket. If oil doesn't flow from the check hole add oil until it reaches the level of the check hole.
  • Page 98 2.Periodic Maintenance MXU 550i Draining Remove the filler cap with a 17 mm socket. Inspect the filler cap O-ring and replace it as needed. 2-43...
  • Page 99 2.Periodic Maintenance MXU 550i Place a suitable oil drain pan under the drain bolt. Remove the drain bolt. Allow the gear oil to drain into the drain pan. Install the drain plug and tighten it to specification. Torque Item Q'ty Thread dia. (mm) Kgf-m (N-m, ft-lb) Rear drive gear oil drain bolt 2 (20, 15)
  • Page 100 2.Periodic Maintenance MXU 550i Remove the filler cap with a 17 mm socket. Inspect the filler cap O-ring and replace it as needed. Remove the check level bolt. Fill the gear oil until the oil level reaches the check bolt hole. Recommended oil: SAE 80 At disassembly:...
  • Page 101 2.Periodic Maintenance MXU 550i Install the filler cap and tighten it securely with a 17 mm socket. Torque Item Q'ty Thread dia. (mm) Kgf-m (N-m, ft-lb) Rear drive gear oil filler cap 1.5 (15, 11) 2-46...

  • Page 102: Spark Arrestor

    2.Periodic Maintenance MXU 550i Spark Arrestor SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Note: Always allow the exhaust system plenty of time to cool before touching it. 2-47...
  • Page 103 2.Periodic Maintenance MXU 550i Remove the three spark arrestor bolts with an 8 mm socket. Remove the spark arrestor and gasket. 2-48...

  • Page 104: Installation

    2.Periodic Maintenance MXU 550i Clean the carbon off of the spark arrestor screen with a wire brush. Inspect the spark arrestor screen for any damage and replace as needed. Installation Install the spark arrestor with a new gasket. 2-49...
  • Page 105 2.Periodic Maintenance MXU 550i Install the spark arrestor bolts and tighten them securely with an 8 mm socket. 2-50...

  • Page 106: Spark Plug

    2.Periodic Maintenance MXU 550i Spark Plug SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Spark plug NGK-CR7E Spark plug gap 0.6 - 0.7 mm (0.024 - 0.028 in.) Removal Remove these components Component Topic Seat Seat Fuel tank and shield Fuel Tank Pull the spark plug cap off of the spark plug.
  • Page 107 2.Periodic Maintenance MXU 550i Clean off the area surrounding with compressed air or a shop towel to make sure debris doesn't get into the combustion chamber when the spark plug is removed. NOTE: Always wear safety glasses when using compressed air and never point it directly at yourself or anyone else.
  • Page 108 2.Periodic Maintenance MXU 550i Inspection Inspect the spark plug for signs of damage. Always replace a spark plug if any part of it is damaged. The color of the spark plug's porcelain tip can indicate how the mixture is burning. A white colored plug shows a lean mixture, where a dark plug shows a rich mixture.
  • Page 109 2.Periodic Maintenance MXU 550i If the plug is dirty or has carbon build up it can be cleaned with small wire brush. Do not hesitate to replace a spark plug. Always check the gap of the spark plugs before installation. If the gap needs to be adjusted bend the ground electrode carefully.
  • Page 110 2.Periodic Maintenance MXU 550i Installation Install the spark plug by hand. Tighten it to specification a 5/8 in deep well spark plug socket. TORQUE ITEM THREAD SIZE AND TYPE kgf-m ft-lb SPARK PLUG M10 X 1.0 9.8-13.7 1.0-1.4 2-55...
  • Page 111 2.Periodic Maintenance MXU 550i Do not over tighten the spark plug. The cylinder head is made out of soft metal, and it can be easily damaged. Install the spark plug cap onto the spark plug. Install these components Component Topic Fuel tank and shield Fuel Tank Seat...

  • Page 112: Throttle Free Play

    2.Periodic Maintenance MXU 550i Throttle Free Play SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Inspection Inspect the throttle free play by operating the throttle lever. The free play should be 3 - 5 mm (0.125 - 0.20 in) measured at the end of the throttle lever. The free play is the distance from the lever at rest to where resistance is felt.
  • Page 113 2.Periodic Maintenance MXU 550i To adjust the throttle free play loosen the knurled lock nut on the throttle cable. Turn the adjuster out to decrease free-play and turn it in to increase free-play. 2-58...
  • Page 114 2.Periodic Maintenance MXU 550i Always check that the throttle operates freely and returns properly. Tighten the knurled lock nut securely. Slide the rubber cover into place. 2-59...

  • Page 115: Throttle Limiter

    2.Periodic Maintenance MXU 550i Throttle Limiter The throttle limiter can be used to adjust how much the throttle can be open. Loosen the locknut and turn the screw to adjust the throttle. Do not adjust the screw so that it is more than 13 mm out from the housing.

  • Page 116: Tires

    2.Periodic Maintenance MXU 550i Tires SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Tire Size Front wheel AT 25 X 8-12 Tires (standard models) Rear wheel AT 25 X 10-12 2-61...

  • Page 117: Air Pressure

    2.Periodic Maintenance MXU 550i Air Pressure Check the tire pressure with a low pressure gauge. Front (standard) 0.35 kgf/cm (35 Kpa, 5.0 psi) Tire pressure Rear (standard) 0.32 kgf/cm (32Kpa, 4.5 psi) 2-62...

  • Page 118: Tire Tread Depth

    2.Periodic Maintenance MXU 550i Tire Tread Depth Check that the tire tread depth is within specification. Tire Tread Depth Service Limit Front Tire 4 mm (0.16 in) Rear Tire 4 mm (0.16 in) Directional Rotation Check the "ROTATION" arrow on the tire's sidewall. The arrow indicates the direction in which the tire should turn going forward.

  • Page 119: Suspension And Steering Inspection

    2.Periodic Maintenance MXU 550i Suspension and Steering Inspection SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Place the machine on a level place. Check the steering column bushings and bearings: Move the handlebar up and down, and/or back and forth. Replace the steering column bushings and or bearings if excessive play.
  • Page 120 2.Periodic Maintenance MXU 550i Replace the tie-rod ends if tie-rod end has any vertical play. See the Tie-Rods topic for more information. Raise the front end of the machine so that there is no weight on the front wheels. Check ball joints and/or wheel bearings.
  • Page 121 2.Periodic Maintenance MXU 550i Replace the front arms and/or wheel bearings if there excessive free play. See the A-arms Steering Knuckles topics for more information. Inspect the rear suspension in the same manner. See the Rear Suspension chapter for more information. 2-66...
  • Page 122 2.Periodic Maintenance MXU 550i Pre-load The shock absorbers have adjustable preload collars. Turn the preload collar with a pin spanner to adjust the spring preload. Increase the amount or preload for heavy loads. Note: Always adjust both front shock absorber spring pre-load to the same setting. Uneven adjustment can cause poor handling and loss of stability.

  • Page 123: Toe-In Check

    2.Periodic Maintenance MXU 550i Standard position: 2 Minimum (Soft) position: 1 Maximum (Hard) position: 5 Toe-in Check Make sure the vehicle is clean and mud free. Position the vehicle on a level surface at its operating weight without a rider. Check that all tires are properly inflated at the same pressure.
  • Page 124 2.Periodic Maintenance MXU 550i Straighten the front wheels on a level surface. The handlebar must be positioned straight ahead. Measure the handlebar position on each side to confirm this. Do not change the handlebar position from straight ahead. Measure the distances between the center of the tires with a toe-in-gauge on the front of the tires.
  • Page 125 2.Periodic Maintenance MXU 550i Adjustment Mark the tie-rods for reference. The outer tie-rod locknuts have reverse threads. Loosen the tie-rod locknuts with a 19 mm wrench. 2-70...
  • Page 126 2.Periodic Maintenance MXU 550i Turn the tie-rod flats with a 17 mm wrench. Turn the tie rods evenly until till the toe-in is within specification. Moving the tie-rods out towards the wheels will narrow the distance between the front of the tires. Moving the tie-rods towards the center will increase the distance between the front of the tires.
  • Page 127 2.Periodic Maintenance MXU 550i Tighten the tie-rod locknuts to specification with a 19 mm wrench. Torque Item Q'ty Thread dia. (mm) Kgf-m (N-m, ft-lb) Tie-rod adjusting nut 3.5 (35, 25.5) After adjusting the toe-in take the machine for a slow test ride. If the machine pulls to the left or right when the steering wheel is facing straight ahead the toe-in needs to be readjusted more evenly.

  • Page 128: Valve Clearance

    2.Periodic Maintenance MXU 550i Valve Clearance SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Inspection Remove these components Component Topic Seat Seat Fuel tank and shield Fuel Tank Side covers Side Covers Right mudguard Mudguards and Footrests Recoil starter cover Recoil Starter Cover Spark plug...
  • Page 129 2.Periodic Maintenance MXU 550i Turn the crankshaft clockwise with a 19 mm socket. Align the "T" mark on the flywheel with the index mark on the right crankcase cover. This shows the piston is at Top Dead Center (TDC). 2-74...
  • Page 130 2.Periodic Maintenance MXU 550i Make sure the punch marks on the ends of the camshafts are pointed up. With the marks pointing up the piston is at TDC on the compression stroke. If the punch marks are not pointing up rotate the crankshaft clockwise until the piston is at TDC on the compression stroke.
  • Page 131 2.Periodic Maintenance MXU 550i Adjustment Use a valve adjuster tool to adjust the valves. Special Tool- VSpecial Tool- Valve Adjuster: A120E00080 Loosen the valve adjuster locknut with a wrench. Insert the valve adjuster tool through the opening as shown. If the valve clearance is too tight, back out the valve adjusting screw with the valve adjustment tool.
  • Page 132 2.Periodic Maintenance MXU 550i Assembly Install the timing cap on the right side of the engine and tighten it securely with a flat blade screwdriver. Install these components Component Topic Cylinder head cover Cylinder Head Cover Spark plug Spark Plug Recoil starter cover Recoil Starter Cover Right mudguard...

  • Page 133: Fuel System

    3.Fuel System MXU 550i Fuel System This chapter covers the location and servicing of the fuel system components for the fuel injected KYMCO MXU 550i models. Airbox ..............................4 Check Engine Lamp (CELP) ........................9 Component Location .......................... 13 Diagnostic Tool ........................... 18 Fuel Injection Sensors ........................

  • Page 134: Troubleshooting

    3.Fuel System MXU 550i ● Do not damage the throttle body. It may cause incorrect throttle and idle valve synchronization. ● When the fuel pump is removed make sure it is stored in a clean area where it cannot fall and be damaged.
  • Page 135 3.Fuel System MXU 550i Backfiring or misfiring during acceleration • Ignition system malfunction Engine stall, hard to start, rough idling • Intake air leak • Fuel contaminated/deteriorated • Pinched or clogged fuel hose • Idle speed fail to adjust • Wet spark plug Poor performance (drive ability) and poor fuel economy •...

  • Page 136: Airbox

    3.Fuel System MXU 550i Airbox SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove the air filter. See the Air Filter Servicing topic for more information. Squeeze the breather hose clip and slide it back. Free the breather hose from the airbox boot.
  • Page 137 3.Fuel System MXU 550i Loosen the throttle body to airbox clamp with a #2 Phillips screwdriver. Free the airbox from the throttle body. Remove the airbox. Cover the mouth of the throttle body with a clean shop towel or tape to prevent debris from entering the engine.

  • Page 138: Installation

    3.Fuel System MXU 550i Installation Fit the airbox into place. Connect the airbox to the throttle body.
  • Page 139 3.Fuel System MXU 550i Install the bracket and two airbox bolts. Tighten the airbox bolts securely. Tighten the airbox to throttle body clams securely with a #2 Phillips screwdriver.
  • Page 140 3.Fuel System MXU 550i Connect the breather hose to the airbox boot. Secure the hose with the clamp. Install the air filter. See the Air Filter Servicing topic for more information.

  • Page 141: Check Engine Lamp (Celp)

    3.Fuel System MXU 550i Check Engine Lamp (CELP) SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Display Indicators Note: The check engine lamp (CELP) will come on for 2 seconds when the key is turned on. It should go off when the engine is started. If it lights after this the system has detected a problem.
  • Page 142 3.Fuel System MXU 550i The wrench icon on the display will come on when the key is turned on and go away when the engine has started. If the wrench icon come on the this indicates and EFI system electric part fault and and a failure code is present. Failure Code Indicator If the ECU connectors, or battery leads are disconnected the stored malfunction codes will be lost.

  • Page 143: Self-Diagnostic Procedures

    3.Fuel System MXU 550i Without Diagnostic Special Tool SELF-DIAGNOSTIC PROCEDURES ● Turn key to the ON position. ● The CELP will light for two seconds and then go off. ● If the engine has problem, the CELP will blink to show the failure codes. ●...

  • Page 144: Self-Diagnosis Reset Procedure

    3.Fuel System MXU 550i In this example the failure codes corresponding with 21 and 22 blinks need to be evaluated. To see the full list of trouble codes see the Diagnostic Trouble Codes (DTCs) topic. With Special Tool See the Fuel Injection Diagnostic Tool topic.

  • Page 145: Component Location

    3.Fuel System MXU 550i Component Location SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Right Side Regulator/Rectifier Gear Position Switch Winch Leads Stator Coil and Ignition Pulse Generator / Crank Position Sensor 3-13...
  • Page 146 3.Fuel System MXU 550i Left Side and Center Roll Sensor (Tip-over Switch) Diagnostic Tool Connector Throttle Body Ignition Coil Spark Plug Water Temperature Sensor 3-14...

  • Page 147: Throttle Body

    3.Fuel System MXU 550i Throttle Body The following components can be found here. Throttle Body • T-MAP (Manifold Air Pressure) • Fuel Injector • Fuel Hose • TPS (Throttle Position Sensor) • ISC (Idle Speed Control) • 3-15...
  • Page 148 3.Fuel System MXU 550i Under The Seat Winch Leads (optional) Battery Relays (see below) Starter Relay Fuse Box 3-16...
  • Page 149 3.Fuel System MXU 550i Relays Fan Relay Engine Start Relay Fuel Pump Relay Switched Power Relay Fuel Pump The fuel pump is located inside the fuel tank. 3-17...

  • Page 150: Diagnostic Tool

    Integrated Linker : 3620A-AGD7-9002 3620A-LEB2-E00 This tool has been developed by KYMCO and for KYMCO vehicles only. The tool software can be updated for new models with a computer via the USB cable. Please refer to the specifications when servicing this vehicle. See the...
  • Page 151 3.Fuel System MXU 550i Plug the diagnostic tool connector into the CAN Linker as shown. Remove the front cover to access the diagnostic tool connector. See the Front Cover topic for more information. 3-19...
  • Page 152 3.Fuel System MXU 550i Remove the dummy side of the connector. Set a multimeter to reads voltage (DCV). Measure the voltage as indicated. Terminal (+) Terminal (-) Normal BR/L Battery Voltage Battery Voltage - 1 Connect the CAN Linker to the diagnostic plug. Turn on the ignition switch to send power to the tool.
  • Page 153 3.Fuel System MXU 550i The functions of the diagnostic tool include ECU version, model name, data analysis and adjust. ECU version: includes model name, ECU number, identifications number and software version. DTC Inspect: DTC reading, DTC clearing, and troubleshooting. Data Analyze: For ECU’s setting inspection and running condition analysis. Adjust: Not allowed ECU Version The four functions will display when the tool is powered on.
  • Page 154 3.Fuel System MXU 550i AKG9 Pressing the enter button on the ECU version will show information on the ECU software and calibration. Press the down button (right) to return to the first page. DTC (Diagnostic Trouble Code) INSPECTION PROCEDURE AKG9 Press the down button (right) to move the item selector down to the DTC Inspect item.
  • Page 155 3.Fuel System MXU 550i Pressing the enter button on the DTC Inspect item will bring up the options shown above. Select the DTC Load option and press the enter button to display the DTC options. There are three DTC options - Active, Occurred, and History. Move the selector to the Active option and press enter to display current DTC.
  • Page 156 3.Fuel System MXU 550i The diagnostic tool will display all current DTC. In the photo above only one code (12) is showing. Select the code number of interest and press enter for more information on that DTC. In this instance the indicated code is 12 (CELP blinks). This corresponds to the DTC P0230.
  • Page 157 3.Fuel System MXU 550i Failure Blinks Fault description Priority Fault management Codes 1. Make sure the relay connector is Fuel pump relay or connected correctly. P0230 electric circuit 2. Check if the ECU sends a signal to malfunction relay. 3. Check the fuel pump relay resistance Consult the DTC table for more information on how to troubleshoot the problem.
  • Page 158 3.Fuel System MXU 550i Pressing the enter button on the DTC Inspect item will bring up the options shown above. Move the selector down to the Clear DTC option and press enter. The diagnostic tool will show when the DTC in memory is cleared. Also, the DTC indicator light will be off.
  • Page 159 3.Fuel System MXU 550i Data Analysis Procedure When using the data analysis feature for running condition items such as ignition advance, ISC step, ect., make sure the engine temperature has reached 80° C. The engine temperature is displayed on data analysis page 03. AKG9 Press the down button (right) to move the item selector down to the DATA Analyze item.
  • Page 160 3.Fuel System MXU 550i Page 02 The 02 page shows TPS position and TPI idle adapted. Page 03 The 03 page shows engine temperature, air temperature, and intake pressure. 3-28...
  • Page 161 3.Fuel System MXU 550i Page 04 The 04 page shows atmospheric pressure, fuel injection interval, and ignition advance. Page 05 The 05 page shows the rollover voltage. 3-29...
  • Page 162 3.Fuel System MXU 550i Page 06 The 06 page shows the ISC step and ISC learn step. Page 07 The 07 page shows the ECU counter. 3-30...

  • Page 163: Fuel Injection Sensors

    3.Fuel System MXU 550i Fuel Injection Sensors SAFETY FIRST: Protective gloves and eyewear are recommended at this point. You will need a digital multimeter to inspect the sensors. Water Temperature Sensor (WTS) Removal Remove the left side cover. See the Side Covers topic for more information.
  • Page 164 3.Fuel System MXU 550i Push in the spring and unplug the WTS sensor connector. Remove the sensor with a 22 mm wench. 3-32...
  • Page 165 3.Fuel System MXU 550i Installation Thread in the WTS. Tighten the WTS to specification with a deep well 22 mm socket. ITEM kgf-m ft-lb Inspection Input Voltage Turn the ignition switch to the OFF position. 3-33...
  • Page 166 3.Fuel System MXU 550i Push in the spring and unplug the WTS sensor connector. Set the multimeter to read voltage (DCV). Turn the ignition switch to the ON position. Measure the input voltage on the harness side of the connector. (WTS Input Voltage: 5 ±...
  • Page 167 3.Fuel System MXU 550i Suspend the sensor and a thermometer in a pot of coolant with string. Make sure the WTS and the thermometer are not touching the pot. Bring the temperature up to the specification slowly and check the resistance between the sensor terminal and body. Temperature Standard Resistance (approximate) 60°...

  • Page 168: Input Voltage Inspection

    3.Fuel System MXU 550i Manifold Air Temperature Pressure (T-MAP) To remove and install the sensors on the throttle body see the Throttle Body Components topic. Input Voltage Inspection Turn the ignition switch to the OFF position. Unplug the T-MAP connector. Set the multimeter to read voltage (DCV).

  • Page 169: Throttle Position Sensor

    3.Fuel System MXU 550i Resistance Set the multimeter to ohms of resistance (kΩ). Measure the resistance between the 3 and 4 pins of the T-MAP sensor. ITEM SPECIFICATION T-MAP sensor resistance (20°C) 1613 - 2544 Ω To replace the T-MAP sensor see the Throttle Body Components topic.

  • Page 170: Resistance Inspection

    3.Fuel System MXU 550i Measure if the ECU voltage outputs to TPS between the following terminals of the TPS connector. Terminal Normal Violet/Red (+) – Violet/Green (-) Resistance Inspection Set the multimeter to ohms of resistance (kΩ). Measure the resistance between the ground (A) and input (C) terminals of the TPS. Throttle Position Sensor (TPS) 3500 - 6500 Ω...
  • Page 171 3.Fuel System MXU 550i Throttle Position Opening Angle Standard Close 0.67 ± 0.05 V Open > 90 % 1.8 - 2.3 V To replace the TPS see the Throttle Body Components topic. Crankshaft Position Sensor (CKP) See the ignition pulse generator in the Generator Cover topic.
  • Page 172 3.Fuel System MXU 550i Remove the two roll sensor screws with a #2 Phillips screwdriver. Unplug the roll sensor and remove it. Plug in the roll sensor and install it so the UP mark faces up. Tighten the two roll sensor screws securely with a #2 Phillips screwdriver.
  • Page 173 3.Fuel System MXU 550i Inspection Turn the ignition switch to the OFF position. Remove the roll sensor screws, but leave the sensor plugged in. Set the multimeter to read voltage (DCV). Turn the ignition switch to the ON position. Measure the voltage of the roll sensor wires with the connector plugged in and the sensor in the regular upright attitude.
  • Page 174 3.Fuel System MXU 550i Incline the roll sensor 65 ± 10 degrees to the left or right. Check the voltage. Terminal Normal Violet/Red (+) - Green (-) 5 V (ECU Voltage) Black/White (+) - Green (-) 0.4 - 1.4 V If this test is to be repeated the ignition switch must be turned OFF to reset the system.

  • Page 175: Fuel Injector

    3.Fuel System MXU 550i Fuel Injector SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Warning: Gas is extremely flammable! Do not work around an open flame or a source of sparks. Removal Remove these components Component Topic Seat Seat Side covers...
  • Page 176 3.Fuel System MXU 550i Push in the spring clip and unplug the fuel injector connector. 3-44...
  • Page 177 3.Fuel System MXU 550i Disassembly Remove the two fuel injector mounting bolts with a 10 mm socket. Remove the fuel injector and pipe from the intake pipe. 3-45...
  • Page 178 3.Fuel System MXU 550i Slide off the clip and pull the fuel injector out of its pipe. The O-rings should be replaced with new items on installation. 3-46...

  • Page 179: Installation

    3.Fuel System MXU 550i Installation Install new O-rings to the fuel injector. Apply a light coat of fresh engine oil to the fuel injector O-ring seals. Install the fuel injector into the pipe. Install the clip to secure the fuel injector. 3-47...
  • Page 180 3.Fuel System MXU 550i Install fuel injector and pipe onto the intake pipe. Guide the fuel injector into place, and be sure not to damage the O-ring. Install the two fuel injector mounting bolts and tighten them securely. 3-48...
  • Page 181 3.Fuel System MXU 550i Install the fuel injector into the pipe. Install the clip to secure the fuel injector. 3-49...
  • Page 182 3.Fuel System MXU 550i Install fuel injector and pipe onto the intake pipe. Guide the fuel injector into place, and be sure not to damage the O-ring. Fit the post on the fuel pipe into the slot on the intake manifold. Install the bolt and tighten it securely with an 8 mm socket.
  • Page 183 3.Fuel System MXU 550i Installation Plug in the fuel injector connector. Connect the fuel hose to the fuel injector pipe. Tighten the fuel hose clamp securely with a #2 Phillips screwdriver. Install these components Component Topic Fuel tank and shield Fuel Tank Side covers Side Covers...

  • Page 184: Fuel Pump

    3.Fuel System MXU 550i Fuel Pump SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Warning: Gas is extremely flammable! Do not work around an open flame or a source of sparks. Fuel Line Inspection Remove the seat. See the Seat topic for more information.
  • Page 185 3.Fuel System MXU 550i Unplug the fuel pump connecter. Set the multimeter to read voltage (DCV). Touch the multimeter leads to the harness side of the fuel pump connector, with the positive lead touching the orange/red wire terminal and the negative lead touching the green wire terminal.
  • Page 186 3.Fuel System MXU 550i Clean the disconnect fitting and put a rag over it. Push down on the black release and disconnect the fuel fitting from the fuel tank. Place plastic bags over the fuel line ends to keep debris out and prevent damage. Remove the six fuel pump bolts with a 10 mm socket.
  • Page 187 3.Fuel System MXU 550i Remove the fuel pump mounting ring. Note the position of the fuel pump outlet pipe. Mark the fuel tank with the outlet pipe position so the fuel pump can be installed to the correct position. 3-55...
  • Page 188 3.Fuel System MXU 550i Carefully lift out the fuel pump. Guide the fuel level float out of the fuel tank with the pump. Remove the O-ring from the fuel pump. Discard the fuel pump O-ring, and replace it with a new item on assembly.
  • Page 189 3.Fuel System MXU 550i Inspect the fuel filter and replace it as needed. 3-57...

  • Page 190: Fuel Level Gauge Inspection

    3.Fuel System MXU 550i Fuel Level Gauge Inspection Make sure the fuel level gauge float arm moves smoothly. Using a digital multimeter set to ohms of resistance (Ω). Measure the resistance between the gray wire fuel pump/level gauge connector terminals with the float raised to the positions indicted below. 3-58...
  • Page 191 3.Fuel System MXU 550i Fuel Level Float Position Approximate Resistance Full 101 Ω Empty 3 Ω Replace the fuel pump unit with a new part if the resistance is out of specification. Fuel Output Pressure Turn the key to the OFF position. Use a fuel hose clamp to block the flow of fuel to the fuel injector.

  • Page 192: Fuel Pump Relay

    3.Fuel System MXU 550i ITEM SPECIFICATION Fuel pump standard pressure 3 Bar or 43 psi If the fuel pressure is below specification check the fuel line for kinks and clogs. Also, inspect the fuel strainer screen on the fuel pump and the breather hose on the tank. Fuel Pump Relay Turn the ignition switch to the OFF position.
  • Page 193 3.Fuel System MXU 550i Check for continuity between the terminals of the relay that match up with the red/blue and orange/red wires. Jump a 12 V battery to the terminals of the relay that match up with red/yellow and black/red wires. There should be continuity only when 12 V battery connected.
  • Page 194 3.Fuel System MXU 550i Installation Replace the O-ring with new item and apply a small amount of fresh engine oil to the new O-ring. Carefully insert the fuel pump into the tank. Avoid damaging the fuel pump wires and fuel strainer.
  • Page 195 3.Fuel System MXU 550i Position the fuel delivery pipe as shown. Install the fuel pump mounting ring. 3-63...
  • Page 196 3.Fuel System MXU 550i Install the six fuel pump bolts. Tighten the bolts evenly and securely with a 10 mm socket. Connect the fuel hose to the outlet pipe on the fuel pump. Make sure the connector is securely attached to the outlet pipe. 3-64...
  • Page 197 3.Fuel System MXU 550i Plug in the fuel pump connecter. fuel tank cover. See the Fuel Tank topic for more information. Install the seat. See the Seat topic for more information. 3-65...

  • Page 198: Throttle Body Removal And Installation

    Do not damage the throttle body, it may cause the throttle and idle valve to fail • synchronization. The throttle body is preset in the KYMCO factory, do not disassemble it incorrectly. • Do not loosen or tighten the painted bolts and screws for the throttle body. Loosening or •...
  • Page 199 3.Fuel System MXU 550i Unplug the TPS connector. Unplug the T-MAP connector. Loosen the fuel injector hose clamp with a #2 Phillips screwdriver. Disconnect the fuel hose from the fuel injector. 3-67...
  • Page 200 3.Fuel System MXU 550i Push in the spring and unplug the fuel injector connector. Remove the two throttle drum cover screws with a #2 Phillips screwdriver. 3-68...
  • Page 201 3.Fuel System MXU 550i Remove the throttle drum cover. Slide the throttle cable housing out of the throttle body. 3-69...
  • Page 202 3.Fuel System MXU 550i Free the throttle cable from the throttle drum. The throttle body is held to the intake pipe with a clamp. 3-70...
  • Page 203 3.Fuel System MXU 550i Loosen the intake pipe clamp with a #2 Phillips screwdriver. Remove the throttle body from the intake pipe. 3-71...

  • Page 204: Intake Pipe

    3.Fuel System MXU 550i Intake Pipe Remove the two intake pipe bolts that hold the intake pipe to the cylinder head. Remove the intake pipe from the cylinder head. 3-72...
  • Page 205 3.Fuel System MXU 550i Remove the O-ring from the intake To remove the fuel injector see the Fuel Injector topic for more information. To disassemble the throttle body see the Throttle Body Components topic for more information. Installation Intake Pipe Install a new intake pipe O-ring.
  • Page 206 3.Fuel System MXU 550i Fit the intake pipe onto the cylinder head. Install the intake pipe and tighten the bolts securely with a 10 mm socket. 3-74...
  • Page 207 3.Fuel System MXU 550i Throttle Body Fit the throttle body into place as shown. Make sure the ridge on the throttle body fits into the gap on the intake pipe fitting. Tighten the intake pipe throttle body clamp securely with a #2 Phillips screwdriver. 3-75...
  • Page 208 3.Fuel System MXU 550i Fit the end of the throttle cable into the throttle drum. Fit the throttle cable into the throttle body as shown. 3-76...
  • Page 209 3.Fuel System MXU 550i Install the throttle drum cover. Install the two throttle drum cover screws and tighten them securely with a #2 Phillips screwdriver. 3-77...
  • Page 210 3.Fuel System MXU 550i Plug in the fuel injector connector. Connect the fuel hose to the fuel injector pipe. Tighten the fuel hose clamp securely with a #2 Phillips screwdriver. 3-78...
  • Page 211 3.Fuel System MXU 550i Plug in the T-MAP connector. Plug in the TPS connector. 3-79...
  • Page 212 3.Fuel System MXU 550i Plug in the ISC connector. Install these components Component Topic Airbox Airbox Rear Fender Rear Fender Fuel tank and shield Fuel Tank Side covers Side Covers Seat Seat 3-80...

  • Page 213: Throttle Body Components

    3.Fuel System MXU 550i Throttle Body Components SAFETY FIRST: Protective gloves and eyewear are recommended at this point. To remove the throttle body. See the Throttle Body Removal and Installation topic for more information. To inspect the sensors see the Fuel Injection Sensors topic.
  • Page 214 3.Fuel System MXU 550i Remove the T-MAP sensor. ISC (Idle Speed Control - Air Bypass Valve) Remove the two ISC screws with a #2 Phillips screwdriver. 3-82...
  • Page 215 3.Fuel System MXU 550i Remove the ISC from the throttle body. Remove the O-ring from the ISC and discard it. Clean the tip of the ISC valve. Inspection If the engine is hard to start, stops, or idles rough the ISC may be faulty. Use the data analysis feature of the FI Diagnostic Tool to see information on the ISC.

  • Page 216: Tps Sensor

    3.Fuel System MXU 550i The ISC step should be below 65. TPS Sensor The TPS is located on the throttle shaft opposite the throttle drum. 3-84...
  • Page 217 3.Fuel System MXU 550i Remove the TPS sensor with a #2 Phillips screwdriver. Assembly The throttle position sensor (TPS) and idle air bypass valve (ISC) have to be reset when the throttle body MAP, TPS, ISC or ECU have been reinstalled. TPS/ISC Reset Start the engine and let it idle until the engine temperature has reached 85°...
  • Page 218 3.Fuel System MXU 550i Install the TPS onto the throttle body so that it returns to the original position. Install and tighten the screw securely with a #2 Phillips screwdriver. 3-86...
  • Page 219 3.Fuel System MXU 550i ISC (Idle Speed Control - Air Bypass Valve) Apply oil onto a new O-ring and place it on the ISC. Install the ISC into the throttle body as shown, being careful not to damage the O-ring. 3-87...
  • Page 220 3.Fuel System MXU 550i Install the two ISC screws and tighten them securely with a #2 Phillips. T-MAP Sensor Apply oil onto a new O-ring and place it on the T-MAP sensor. 3-88...
  • Page 221 3.Fuel System MXU 550i Install the T-MAP into the throttle body, being careful not to damage the O-ring. Install the T-MAP sensor screw and tighten it securely with a #2 Phillips. Install the throttle body. See the Throttle Body Removal and Installation topic for more information.
  • Page 222 5.Engine MXU 550i Engine MXU 550i This chapter covers the location and servicing of the engine components for the KYMCO MXU 550i. Cylinder Head Cover ..........................8 Camshaft ............................17 Camshaft Installation ......................... 35 Cylinder Head ............................. 49 Valves ..............................60 Cylinder and Piston ..........................

  • Page 223: General Instructions

    5.Engine MXU 550i GENERAL INSTRUCTIONS Lubrication System The maintenance of lubrication system can be performed with the engine installed in the frame. Use care when removing and installing the oil pump not to allow dust and foreign matters to enter the engine If any portion of the oil pump is worn beyond the specified service limits.

  • Page 224: High Oil Pressure

    5.Engine MXU 550i High oil pressure • Pressure relief valve stuck closed • Plugged oil filter, gallery, or metering orifice • Faulty oil pump Seized engine • No or low oil pressure • Clogged oil orifice/passage • Internal oil leak •...
  • Page 225 5.Engine MXU 550i TROUBLESHOOTING • The poor cylinder head operation can be diagnosed by a compression test or by tracing engine top-end noises. Poor performance at idle speed • Compression too low Compression too low • Incorrect valve clearance adjustment •...

  • Page 226: Compression Too High

    5.Engine MXU 550i • When installing the cylinder, use a new cylinder gasket and make sure that the dowel pins are correctly installed. TROUBLESHOOTING When hard starting or poor performance at low speed occurs, check the crankcase breather for white smoke. If white smoke is found, it means that the piston rings are worn, stuck or broken.

  • Page 227: Engine Specifications

    5.Engine MXU 550i Engine Specifications MXU 550i Engine Item Standard mm (in) Service Limit IN 0.1 mm (0.004 in) Valve clearance (cold) EX 0.1 mm (0.004 in) Cylinder head compression 15 kg/cm (1500 kPa, 213 pressure psi) Cylinder head warpage 0.05 (0.002) Camshaft runout 0.05 (0.002)
  • Page 228 5.Engine MXU 550i 0.03 - 0.065 (0.0012 - 0.0026) 0.08 (0.003) Ring-to-groove clearance Second 0.015 - 0.05 (0.0006 - 0.002) 0.065 (0.0026) 0.15 - 0.3 (0.006 - 0.012) 0.5 (0.02) Second 0.03 - 0.45 (0.012 - 0.018) 0.65 (0.026) Ring end gap Piston side 0.2 - 0.7(0.008 - 0.028)

  • Page 229: Cylinder Head Cover

    5.Engine MXU 550i Cylinder Head Cover SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove these components Component Topic Seat Seat Fuel tank and shield Fuel Tank Side covers Side Covers Right mudguard Mudguards and Footrests Spark plug Spark Plug Disconnect the crankcase breather hose from the cylinder head cover.
  • Page 230 5.Engine MXU 550i Remove the four bolts, washers and rubber grommets with a 10 mm socket. Remove the cylinder head cover.
  • Page 231 5.Engine MXU 550i Remove the cylinder head cover gasket. Clean the mating surfaces of the cylinder head and cover. Disassembly 6-10...
  • Page 232 5.Engine MXU 550i Remove the three breather separator bolts with a 10 mm socket. Remove the breather separator. 6-11...
  • Page 233 5.Engine MXU 550i Assembly Install the breather separator. 6-12...
  • Page 234 5.Engine MXU 550i Install the three breather separator bolts and tighten them to specification with a 10 mm socket. ITEM kgf-m ft-lb Breather separator bolt 6-13...

  • Page 235: Installation

    5.Engine MXU 550i Installation Apply fluid gasket (threebond: 1215) to the mating surface of the cylinder head cover, then install the rubber gasket. Install the cylinder head cover. 6-14...
  • Page 236 5.Engine MXU 550i Install the four grommets and washers onto the cylinder head cover. Install the four bolts. Tighten the cylinder head cover bolts a small amount at a time in a crisscross pattern. Tighten the bolts to specification with a 10 mm socket. ITEM kgf-m ft-lb...
  • Page 237 5.Engine MXU 550i Connect the crankcase breather hose to the cylinder head cover. Secure the hose with the clamp. To remove the camshafts see the Camshaft topic. 6-16...

  • Page 238: Camshaft

    5.Engine MXU 550i Camshaft SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove the cylinder head cover. See the Cylinder Head Cover topic for more information. Remove the spark plug. See the Spark Plug topic for more information. Remove the timing cap on the right side of the engine with a flat blade screwdriver.
  • Page 239 5.Engine MXU 550i Remove the recoil starter cover. Turn the crankshaft clockwise with a socket. 6-18...
  • Page 240 5.Engine MXU 550i Align the "T" mark on the flywheel with the index mark on the right crankcase cover. This shows the piston is at Top Dead Center. Make sure the punch marks on the ends of the camshafts are pointed up. With the marks pointing up the piston is at TDC on the compression stroke.

  • Page 241: Cam Chain Tensioner

    5.Engine MXU 550i Cam Chain Tensioner Note: Do not remove the cam chain tensioner until the crank and piston have been turned positioned at TDC. Remove the cam chain tensioner sealing bolt with a 10 mm socket. Remove the two cam chain tensioner bolts with an 8 mm socket. 6-20...
  • Page 242 5.Engine MXU 550i Remove the cam chain tensioner and gasket. Camshafts 6-21...
  • Page 243 5.Engine MXU 550i Remove the two cam chain guide bolts with an 8 mm socket. Remove the cam chain guide. 6-22...
  • Page 244 5.Engine MXU 550i Loosen the indicated eight camshaft holder bolts a small amount at a time in a crisscross pattern with a 12 mm socket. There are five short bolts, two medium bolts, and one long bolt. The five short bolts are size 8 X 71 mm. The two medium bolts are size 8 X 137 mm.
  • Page 245 5.Engine MXU 550i The size of the long bolt is 8 X 210 mm. Remove the cam chain side camshaft holder and the two dowel pins. 6-24...
  • Page 246 5.Engine MXU 550i Slowly loosen and the remaining four camshaft holder bolts a small amount at a time in a crisscross pattern with a 14 mm socket. Remove the two 10 X 220 mm and two 10 X 210 mm camshaft holder bolts. Remove the camshaft holders and dowel pins.
  • Page 247 5.Engine MXU 550i Lift the cam chain and remove the cam shafts and sprocket. Note: Do not let the cam chain fall into the bottom end of the engine. Secure the cam chain with a piece of wire to keep if from falling into the bottom end of the engine.

  • Page 248: Rocker Arms

    5.Engine MXU 550i Rocker Arms Note the location of the rocker arm components so that they can be returned to their original positions. The rocker arms shafts must be removed from the side of the cylinder head opposite the cam chain. 6-27...
  • Page 249 5.Engine MXU 550i Loosen the rocker arm shafts with a 10 mm Allen. Remove the rocker arm shafts and washers from the cylinder head. 6-28...
  • Page 250 5.Engine MXU 550i Remove the rocker arms from the cylinder head. Inspection Inspect the cam chain slipper surface of the cam chain guide for wear or damage. 6-29...
  • Page 251 5.Engine MXU 550i Inspect the camshaft surface of each camshaft holder for scoring, scratches, or other damage. Note: Always replace the camshaft holders and cylinder head as a set. Check the stop pin spring on the exhaust camshaft holder. The pin should move smoothly in and out without binding. Replace the stop pin assembly as needed.
  • Page 252 5.Engine MXU 550i Check that the cam chain tensioner is functioning properly. Make sure the push rod slides smoothly when the locking mechanism is released. Inspect the camshaft sprocket for wear and damage. 6-31...
  • Page 253 5.Engine MXU 550i Inspect the camshaft lobes and journals wear and damage. If there are signs of damage or discoloration inspect the lubrication system. Measure the maximum height of the cam lobes with vernier calipers or a micrometer. Item Standard mm (in) Service Limit IN 37.2614 (1.4905) 37.11 (1.4844)
  • Page 254 5.Engine MXU 550i Place the ends of the camshafts in V-blocks and check the runout with a dial gauge. Camshaft Runout Limit (IN & EX) 0.05 mm (0.002 in) Check the decompression system by turning the decompressor cam on the exhaust camshaft.
  • Page 255 5.Engine MXU 550i Check the rocker arm shafts for signs of damage and wear. If there are signs of damage or discoloration inspect the lubrication system. Measure the outside diameter of the rocker arm shafts in several locations. Item Standard mm (in) Service Limit IN 9.975 - 9.99 (0.399 - 0.3996) 9.9 (0.396)

  • Page 256: Camshaft Installation

    5.Engine MXU 550i Camshaft Installation SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Installation Rocker Arms Lubricate the inside diameter of the rocker arms and the outside diameter of the rocker arm shaft pivot sections with fresh engine oil. Fit the rocker arms into their original locations.
  • Page 257 5.Engine MXU 550i Apply Blue Loctite to the threads of the rocker arm shafts. Install the rocker arm shafts and washers. Tighten the rocker arm shafts to specification with a 10 mm Allen. Item Thread dia. (mm) Torque kgf-m (N-m, ft-lb) Rocker arm shaft 4.5 (45, 32) 6-36...
  • Page 258 5.Engine MXU 550i Camshafts Position the piston at TDC as with removal. See the Camshaft topic for more information. Align the "T" mark on the flywheel with the index mark on the right crankcase cover. This shows the piston is at Top Dead Center. 6-37...
  • Page 259 5.Engine MXU 550i Apply molybdenum oil to the camshaft lobes, the journal holders in the camshaft holders and the cylinder head. Molybdenum oil: a mixture of molybdenum grease and fresh engine oil in a 50:50 ratio. Fit the camshafts into place. Note the exhaust camshaft has a decompressor cam and intake camshaft doesn't.
  • Page 260 5.Engine MXU 550i Double check the timing after the cam chain tensioner is installed. Install the exhaust camshaft holder with he two dowel pins. Note the exhaust camshaft holder has the stopper pin. Fit the intake camshaft holder into place with the two dowel pins. Lubricate the threads of the camshaft holder bolts with fresh engine oil.
  • Page 261 5.Engine MXU 550i Insert the four largest camshaft holder bolts with new washers. Position the four large cylinder head bolts as shown. 6-40...
  • Page 262 5.Engine MXU 550i Insert the intake and exhaust camshaft holder bolts. Wait to install the cam chain side camshaft holder and bolts. Long: 8 X 210 mm Medium: 8 X 137 mm Short: 8 X 71 mm Tighten the bolts 1 - 9 in multiple steps in a crisscross pattern as shown below. Tighten the large bolts with a 14 mm socket and the smaller bolts with a 12 mm socket.
  • Page 263 5.Engine MXU 550i Camshaft Holder / Cylinder Head Bolt Torque kgf-m (N-m, ft-lb) Bolts 1, 2, 3, 4 5, 6, 7, 8, 9 10, 11, 12, 13 Step 1 2.4 (24, 17) 1.2 (12, 9) Step 2 3.8 (38, 27) 2.3 (23, 17) Step 3 4.8 (48, 35)
  • Page 264 5.Engine MXU 550i Fit the cam chain side camshaft holder into place. The arrow on the camshaft holder must face out. 6-43...
  • Page 265 5.Engine MXU 550i Tighten the 10 - 13 bolts to specification with a 12 mm socket in multiple steps as indicated. Camshaft Holder / Cylinder Head Bolt Torque kgf-m (N-m, ft-lb) Bolts 10, 11, 12, 13 Step 4 1.2 (12, 9) Step 5 2.3 (23, 17) Fit the upper cam chain guide into place.
  • Page 266 5.Engine MXU 550i Install the two cam chain guide bolts and tighten them securely with an 8 mm socket. Cam Chain Tensioner Make sure the cam chain tensioner mating surface is clean. Install a new gasket with the cam chain tensioner. 6-45...
  • Page 267 5.Engine MXU 550i Use a small flat blade screwdriver to wind in the cam chain tensioner rod. Hold the screwdriver in place until both tensioner mounting bolts have been installed. Install the two cam chain tensioner mounting bolts and tighten them to specification with an 8 mm socket.
  • Page 268 5.Engine MXU 550i Install the cam chain tensioner sealing bolt and tighten it to specification with a 10 mm socket. Item Thread dia. (mm) Torque kgf-m (N-m, ft-lb) Tensioner sealing bolt 1 (10, 7.2) Adjust the valve clearance. See the Valve Adjustment topic for more information.
  • Page 269 5.Engine MXU 550i Tighten the recoil starter bolts securely with an 8 mm socket. Install the timing cap on the right side of the engine and tighten securely with a flat blade screwdriver. Install the cylinder head cover. See the Cylinder Head Cover topic for more information.

  • Page 270: Cylinder Head

    5.Engine MXU 550i Cylinder Head SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Drain the coolant. See the Coolant topic for more information. Remove the exhaust system. See the Exhaust System topic for more information. Remove the cylinder head cover. See the Cylinder Head Cover topic for more information.
  • Page 271 5.Engine MXU 550i To remove the WTS housing remove the two bolts with an 8 mm socket. 6-50...
  • Page 272 5.Engine MXU 550i Remove the WTS housing and cylinder head coolant stopper from the cylinder head. Discard the WTS housing gasket. Remove the two nuts under the cylinder head with a 10 mm socket. Loosen the cylinder head bolt with a 12 mm socket. 6-51...
  • Page 273 5.Engine MXU 550i Remove the cylinder head bolt. Tap the reinforced areas of the cylinder head with a rubber mallet to free the dowel pins. 6-52...
  • Page 274 5.Engine MXU 550i Lift off the cylinder head. Guide the cam chain through the opening, but do not allow it to fall into the bottom end of the engine. Remove the cylinder head gasket. Remove the two cylinder head dowel pins. To remove the valves see the Valves topic.
  • Page 275 5.Engine MXU 550i Inspection Clean the combustion chamber with contact cleaner, a plastic knife, brush and/or rag. Take care to only remove carbon and not scrape the head. Place a straight edge on the deck of the cylinder head and check for cylinder head warp with a feeler gauge.

  • Page 276: Installation

    5.Engine MXU 550i Check for warp in several places on the head. If the cylinder head is warped it must be resurfaced by a qualified machine shop or replaced. Installation Make sure the cylinder head mating surface is clean. Install the two cylinder head dowel pins. 6-55...
  • Page 277 5.Engine MXU 550i Fit a new cylinder head gasket into place. Install the cylinder head to the cylinder. Guide the cam chain and cam chain guides though the opening in the cylinder head. Remember to keep the cam chain from falling into the bottom end of the engine.
  • Page 278 5.Engine MXU 550i Install the two nuts under the cylinder head with a 10 mm socket. Item Thread dia. (mm) Torque kgf-m (N-m, ft-lb) Cylinder head nut 1 (10, 7.4) Install the cylinder head bolt. Wait to tighten it in sequence with the cylinder head / camshaft holder bolts.
  • Page 279 5.Engine MXU 550i Insert the coolant stopper into the cylinder head if it was removed. Install the WTS housing with a new gasket. Install the two WTS housing bolts and tighten them to specification with an 8 mm socket. Item Thread dia.
  • Page 280 5.Engine MXU 550i Connect the air bleed hose and thermostat hose to the WTS housing. Secure the hoses with the clamps. Plug in the WTS sensor connector. Install the throttle body. See the Throttle Body Removal and Installation topic for more information.

  • Page 281: Valves

    5.Engine MXU 550i Valves SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove the cylinder head. See the Cylinder Head topic for more information. Note the location of all of the valve parts so that they can be returned to their original positions.
  • Page 282 5.Engine MXU 550i Use a valve spring compressor to remove the valves. Special Tools- Valve Spring Compressor: A120E00040 Compress the valve springs only enough to remove the cotters. Remove the cotters from the valve stem with tweezers or a magnet. 6-61...
  • Page 283 5.Engine MXU 550i Remove the spring retainers. Lift out the valve springs. 6-62...
  • Page 284 5.Engine MXU 550i Push the valves out through the bottom of the cylinder head. Remove the stem seals with needle nose pliers and a pick. Discard the old stem seals. Remove the spring seats. Inspection Item Standard mm (in) Service Limit 6-63...
  • Page 285 5.Engine MXU 550i Inner valve spring free length 33.4 (1.336) Outer valve spring free length 38 (1.52) IN 4.975 - 4.99 (0.199 - 0.1996) 4.925 (0.197) Valve stem O.D. EX 4.955 - 4.97 (0.1982 - 0.1988) 4.915 (0.1966) IN 5 - 5.015 (0.2 - 0.2006) 5.03 (0.2012) Valve guide I.D.
  • Page 286 5.Engine MXU 550i Measure the force to compress the valve spring with a scale. Replace the valve spring if it is out of specification. Item Standard Inner valve spring compressed force 3.5 kg (@ 28.7 mm or 1.148 in) Outer valve spring compressed force 13 kg (@ 31.43 mm or 1.2572 in) Check the valve spring for tilt.
  • Page 287 5.Engine MXU 550i Item Standard mm (in) Inner valve spring tilt 1.2 mm (0.048) Outer valve spring tilt 1.2 mm (0.048) Inspect the valve for damage. Measure the valve stem diameter with a micrometer or vernier calipers and compare the measurements with specification. Replace any valves that do not meet the standard.
  • Page 288 5.Engine MXU 550i Item Standard mm (in) Service Limit IN 5 - 5.015 (0.2 - 0.2006) 5.03 (0.2012) Valve guide I.D. EX 5 - 5.015 (0.2 - 0.2006) 5.03 (0.2012) IN 0.01 - 0.037 (0.004 - 0.0015) 0.08 (0.0032) Valve stem-to-guide clearance EX 0.03 - 0.057 (0.0012 - 0.0023) 0.1 (0.004) Replace the cylinder head if the valve guides are out of specification.
  • Page 289 5.Engine MXU 550i Coat the valve stem and end in fresh engine oil. Insert the valve through the valve guide. Twist the valve slowly to work it through the stem seal without damaging the seal. The valve should move smoothly in the guide and make good contact with the seat. Install the valve springs with the tightly spaced coils facing down.
  • Page 290 5.Engine MXU 550i Install the spring retainers to their original locations. Use a valve spring compressor to install the cotters. Compress the valve springs only enough to install the cotters. Special Tools- Valve Spring Compressor: A120E00040 6-69...
  • Page 291 5.Engine MXU 550i Apply grease to the inside of the cotters. Apply a dab of grease to the end of a flat blade screwdriver. Set the keeper in the grease on the screwdriver and insert it onto the valve stem. Repeat this with the other keeper. After the valves have been reassemble place a clean shop towel under the cylinder head in the combustion chamber area and gently tap each valve with a plastic rod and rubber mallet to make sure the valves and cotters are seated properly.

  • Page 292: Cylinder And Piston

    5.Engine MXU 550i Cylinder and Piston SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove the cylinder head. See the Cylinder Head topic for more information. A coolant hose connects the cylinder cooling jacket to the water pump. 6-71...
  • Page 293 5.Engine MXU 550i Loosen the cylinder coolant hose clamp with a #2 Phillips screwdriver. Free the coolant hose from the cylinder. There is a coolant block pin located in the cooling jacket of the cylinder. Remove the block pin from the cylinder. 6-72...
  • Page 294 5.Engine MXU 550i There are two cylinder bolts with washers on the cam chain side of the cylinder. Loosen the two cylinder bolts with an 8 mm socket. Remove the cylinder bolts and washers. 6-73...
  • Page 295 5.Engine MXU 550i Gently tap the cylinder to free it from the crankcases. Lift the cylinder up and off of the crankcases. Guide the cam chain through its opening in the cylinder. Make sure the cam chain and dowel pins do not fall into the bottom end of the engine.
  • Page 296 5.Engine MXU 550i Remove the two dowel pins. Place a clean shop towel around the base of the piston to prevent any parts or debris from falling into the crankcase. 6-75...
  • Page 297 5.Engine MXU 550i Rotate the gap in the piston pin clip so that it sits in the access opening in the piston. Remove the piston pin clip with a pick or needle nose pliers. Discard the piston pin clips. 6-76...
  • Page 298 5.Engine MXU 550i Slide out the piston pin. Do not use a punch and a hammer to remove the pin. Remove the piston. Clean off the cylinder mating surface, but take care to keep debris from falling into the crankcase. 6-77...
  • Page 299 5.Engine MXU 550i Clean the carbon build up off of the piston with a stiff bristled plastic brush. Never use a wire brush to clean a piston. Spread the piston rings and lift them off opposite the gap. Spread the rings the minimum amount during removal.

  • Page 300: Cylinder Bore

    5.Engine MXU 550i Inspection Cylinder Warp Test for cylinder warp with a straight edge and a feeler gauge. Try and insert the feeler gauge of the service limit under the straight edge. Place the straight edge in several places on the cylinder. Item Service Limit Cylinder warpage across top...
  • Page 301 5.Engine MXU 550i Calculate the cylinder taper. The taper is the maximum difference between either yellow and brown or blue and green. Calculate the cylinder out of round. The out of round is greatest out of yellow, purple, or brown minus the smallest of blue, red, or green. 6-80...

  • Page 302: Piston Diameter

    5.Engine MXU 550i Item Standard Service Limit 92.005 - 92.015 92.1 I.D. (3.6802 - 3.6806) (3.684) Warpage 0.01 (0.0004) 0.05 (0.002) Cylinder Taper 0.01 (0.0004) 0.1 (0.004) Out-of-round 0.01 (0.0004) 0.1 (0.004) If the cylinder is out of specification or damaged it should be repaired by a qualified machine shop or replaced.

  • Page 303: Piston-To-Cylinder Clearance

    5.Engine MXU 550i Piston-to-Cylinder Clearance Subtract the diameter of the piston from the maximum front to rear diameter measurement of the cylinder to calculate the piston-to-cylinder clearance. If the clearance is over the service limit the cylinder and piston must be replaced. ITEM STANDARD mm (in) LIMIT...

  • Page 304: Piston Ring End Gap

    5.Engine MXU 550i Piston Ring End Gap Insert the top ring into the cylinder. Push the top ring in the cylinder. Use the piston to push in the ring to keep it square with the cylinder. Measure the ring gap with a feeler gauge. Repeat this procedure with second ring. ITEM STANDARD mm (in) LIMIT...
  • Page 305 5.Engine MXU 550i Piston Pin O.D. Measure the piston pin outside diameter with a micrometer. Item Standard Service Limit 21.994 - 22 21.96 Piston pin O.D (0.8798 - 0.88) (0.8784) Piston Pin Bore I.D. 6-84...

  • Page 306: Connecting Rod Small End

    5.Engine MXU 550i Measure the piston pin bore diameter with vernier calipers or dial gauge with a small bore gauge. Special Tools- Dial Gauge (1/1000 mm, 1 mm): 09900-20602 Small Bore Gauge (18 - 35 mm): 09900-22403 Item Standard Service Limit 22.002 - 22.008 22.04 Piston pin hole I.D.
  • Page 307 5.Engine MXU 550i Assembly Clean the piston ring grooves, and apply fresh engine oil to the piston rings. Spread the rings the minimum amount possible to install them. Install the oil ring first then the steel rails above and below the oil ring. Install the second ring with the "RN"...
  • Page 308 5.Engine MXU 550i Install the top ring with the "R" mark facing up. The top ring's upper inside edge is chamfered. 6-87...
  • Page 309 5.Engine MXU 550i The top, second, and oil rings should be rotated so that their gaps divide the piston into thirds, or 120° apart. The gaps shouldn't line up with the gaps of any of the other rings. Also, none of the ring gaps should line up with the piston pin. 6-88...
  • Page 310 5.Engine MXU 550i Lubricate the piston pin and the small end of the connecting rod with fresh engine oil. Install the piston onto the connecting rod. The IN marks on the piston must sit on the intake side of the engine. Insert the piston pin.
  • Page 311 5.Engine MXU 550i Place a clean shop towel around the base of the piston to prevent any parts or debris from falling into the crankcase. Install new piston pin clips securely into their grooves. Turn the gap in the clips away from the access gap. 6-90...
  • Page 312 5.Engine MXU 550i Make sure the cylinder mating area is clean. Install the two dowel pins. Install the new base gasket. 6-91...
  • Page 313 5.Engine MXU 550i Coat the inside of the cylinder, piston rings, and piston in fresh engine oil. Lower the cylinder into place and guide the piston into the cylinder while you are compressing the rings with your fingers. Be careful to not damage the rings during this step. Bring the cam chain and guides through the opening.

  • Page 314: Recoil Starter Cover

    5.Engine MXU 550i Recoil Starter Cover SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Note: The recoil starter mechanism is not installed. Removal Remove the right side cover and right mudguard. See the Side Covers Mudguards and Footrests topics for more information.
  • Page 315 5.Engine MXU 550i Remove the recoil starter cover. Remove the belt case and hold the drive pulley to keep the crank from turning with a drive pulley holder. See the Belt Case Cover topic for more information. Special Tool - Drive Pulley Holder: A120E00058 Loosen the recoil starter nut with a 19 mm socket.
  • Page 316 5.Engine MXU 550i Remove the recoil starter nut and washer. Slide out the recoil starter drum. Be careful to not damage the oil control rings. 6-95...
  • Page 317 5.Engine MXU 550i Inspect the recoil starter oil control rings. To replace the oil control rings carefully unlock the rings and remove them. 6-96...

  • Page 318: Installation

    5.Engine MXU 550i Inspect the recoil starter bearing and seal. Remove the generator cover to replace the bearing and seal as needed. See the Generator Cover topic for more information. Installation 6-97...
  • Page 319 5.Engine MXU 550i Install the oil control rings to the recoil starter. Lock the rings as shown above. Apply fresh engine oil to the oil control rings and the recoil starter seal. Carefully install the recoil starter so that the oil control rings are not damaged. 6-98...
  • Page 320 5.Engine MXU 550i Install the washer and the recoil starter nut. Hold the drive pulley to keep the crank from turning with a drive pulley holder. Special Tool - Drive Pulley Holder: A120E00058 Tighten the recoil starter nut to specification with a 19 mm socket. ITEM kgf-m ft-lb...
  • Page 321 5.Engine MXU 550i Install the recoil starter cover. Tighten the recoil starter bolts securely with an 8 mm socket. Install the frame covers. See the Side Covers topic for more information. 6-100...

  • Page 322: Generator Cover

    5.Engine MXU 550i Generator Cover SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Generator Cover Remove the right side cover and right mudguard. See the Side Covers Mudguards and Footrests topics for more information. Drain the coolant. See the Coolant topic for more information.
  • Page 323 5.Engine MXU 550i Loosen the 14 generator cover bolts evenly in a crisscross pattern. Remove the 14 generator cover bolts with an 8 mm socket. 6-102...
  • Page 324 5.Engine MXU 550i Utilize the pry points and remove the generator cover from the crankcase. Remove the generator cover gasket. Remove the two generator cover dowel pins. 6-103...
  • Page 325 5.Engine MXU 550i Inspect the oil jet and passages for clogging. Clean them out if needed. Stator and Ignition Pulse Generator The stator and ignition pulse generator must be removed together. 6-104...
  • Page 326 5.Engine MXU 550i Remove the three stator coil mounting bolts with an 8 mm socket. Remove the two ignition pulse generator bolts with an 8 mm socket. Free the ignition pulse generator and rubber wire grommet from the generator cover. 6-105...
  • Page 327 5.Engine MXU 550i Lift out the stator and ignition pulse generator together. If the bearing in the generator cover needs to be replaced remove the snap ring. Drive the bearing out from the outside in. Drive in the new bearing with a suitable driver that is the same outside diameter as the bearing.
  • Page 328 5.Engine MXU 550i Installation Fit the stator and ignition pulse generator into the cover together. Install the three stator coil mounting bolts and tighten them to specification with an 8 mm socket. ITEM kgf-m ft-lb Stator coil bolt 6-107...
  • Page 329 5.Engine MXU 550i Install the two ignition pulse generator bolts and tighten them to specification with an 8 mm socket. ITEM kgf-m ft-lb Ignition pulse generator 6-108...
  • Page 330 5.Engine MXU 550i Generator Cover Apply a silicone sealant to the outside of the rubber wire grommet where it will fit into the generator cover and crankcase. Fit the grommet into the cover. Install the two dowel pins and a new generator cover gasket. 6-109...
  • Page 331 5.Engine MXU 550i Fit the generator cover onto the crankcase. Install the 14 generator cover bolts. Tighten the bolts a small amount at a time in a crisscross pattern. 6-110...
  • Page 332 5.Engine MXU 550i Tighten the generator cover bolts to specification with an 8 mm socket. Plug in the 4-pin stator connector. Plug in the 2-pin ignition pulse generator / crank position sensor connector. Install the recoil starter. See the Recoil Starter Cover topic for more information.
  • Page 333 5.Engine MXU 550i Fill the coolant. See the Coolant topic for more information. Install the right mudguard and side cover. See the Mudguards and Footrests Side Covers topics for more information. 6-112...

  • Page 334: Flywheel

    5.Engine MXU 550i Flywheel SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove the right side cover and right mudguard. See the Side Covers Mudguards and Footrests topics for more information. Drain the coolant. See the Coolant topic for more information.
  • Page 335 5.Engine MXU 550i Special Tool- Flywheel Puller: A120E00060 Apply grease to the threads of the flywheel puller. Hold the body of the puller with a large wrench and turn in the pusher bolt to separate the flywheel from the crankshaft. Remove the flywheel from the crankshaft.
  • Page 336 5.Engine MXU 550i Remove the woodruff key from the crankshaft. Slide off the starter driven gear. 6-115...
  • Page 337 5.Engine MXU 550i Starter Reduction Gear Remove the starter reduction gear from the crankcase. 6-116...

  • Page 338: Starter Clutch

    5.Engine MXU 550i Inspect the starter reduction gear for wear and damage. Replace the part as a whole if needed. Starter Clutch The starter clutch and starter driven gear ride on the back of the flywheel. 6-117...
  • Page 339 5.Engine MXU 550i Inspect the function of the starter clutch by turning the starter driven gear. You should be able to turn the driven gear clockwise smoothly, but the gear should not turn counterclockwise. If the starter clutch allows the gear to turn either way, or will not turn smoothly it must be replaced.
  • Page 340 5.Engine MXU 550i Inspect the starter driven gear for wear and damage. Measure the outside diameter of the starter driven gear boss and the inside diameter of the starter driven gear where it rides on the crankshaft. Item Service Limit Starter driven gear boss O.D.
  • Page 341 5.Engine MXU 550i Loosen the starter clutch bolts from the outside of the flywheel with a 6 mm Allen. Remove the starter clutch bolts. 6-120...
  • Page 342 5.Engine MXU 550i Remove the starter clutch and mounting plate from the back of the flywheel. Remove the starter clutch from the mounting plate. 6-121...

  • Page 343: Installation

    5.Engine MXU 550i Installation Starter Clutch Fit the starter clutch into the mounting plate. Place the starter clutch and mounting plate on the back of the flywheel. 6-122...
  • Page 344 5.Engine MXU 550i Apply a thread locking agent to the threads of the six starter clutch bolts. Tighten the starter clutch bolts evenly and securely with a 6 mm Allen. 6-123...
  • Page 345 5.Engine MXU 550i Lubricate the boss of the starter driven gear with a 50:50 mixture of engine oil and molybdenum grease. Rotate the starter driven gear clockwise as it is inserted into the starter clutch. 6-124...
  • Page 346 5.Engine MXU 550i Starter Reduction Gear Lubricate the starter reduction gear shaft with fresh engine oil. Install the starter reduction gear into the crankcase as shown. 6-125...
  • Page 347 5.Engine MXU 550i Flywheel Install the starter driven gear onto the crankshaft. Install the woodruff key into the crankshaft. Make sure the tapered area of the crankshaft is clean, oil free, and dry. 6-126...
  • Page 348 5.Engine MXU 550i Guide the flywheel onto the crankshaft make sure the key lines up with the groove in the flywheel. Rotate the starter driven gear to fit it into the starter clutch if needed. Install the left crankcase cover. See the Generator Cover topic fore more information.

  • Page 349: Oil Pump

    5.Engine MXU 550i Oil Pump SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove the right side cover and right mudguard. See the Side Covers Mudguards and Footrests topics for more information. Drain the coolant. See the Coolant topic for more information.
  • Page 350 5.Engine MXU 550i Remove the two oil pump chain guide bolts with an 8 mm socket. Remove the oil pump chain guide. 6-129...
  • Page 351 5.Engine MXU 550i Loosen the two oil pump oil separator bolts with an 8 mm socket. Remove the oil separator bolts and the oil separator. Remove the snap ring with snap ring pliers. 6-130...
  • Page 352 5.Engine MXU 550i Slide the oil pump sprocket off of the oil pump shaft. Free the oil pump chain from the crankshaft and remove the oil pump sprocket and chain. 6-131...
  • Page 353 5.Engine MXU 550i Remove the oil pump shaft holder bolt with an 8 mm socket. Remove the oil pump shaft holder. Remove the two oil pump shaft holder dowel pins. 6-132...
  • Page 354 5.Engine MXU 550i Remove the two oil pump bolts with an 8 mm socket. Remove the oil pump. Turn the oil pump shaft and make sure it turns smoothly. 6-133...
  • Page 355 5.Engine MXU 550i Disassembly Slide the oil pump shaft out of the oil pump. 6-134...
  • Page 356 5.Engine MXU 550i Remove the oil pump cover screw. Remove the oil pump cover. Remove the oil pump dowel pin. 6-135...
  • Page 357 5.Engine MXU 550i Remove the inner and outer oil pump rotors. Inspection Check the oil pump chain guide for signs of excessive wear and damage. Replace it as needed. 6-136...
  • Page 358 5.Engine MXU 550i Inspect the oil pump chain and sprocket for excessive wear and damage. Replace these components as needed. Use a feeler gauge set to check the clearance between the outer oil pump rotor and the body (body clearance). 6-137...
  • Page 359 5.Engine MXU 550i Use a feeler gauge set to check the clearance between the inner and outer rotors (tip clearance). Place a straight edge across the oil pump body and rotors. Check the side clearance with a feeler gauge. ITEM STANDARD mm (in) SERVICE LIMIT Tip clearance...
  • Page 360 5.Engine MXU 550i Replace the oil pump if the oil pump rotors are damaged or the measurements are out of specification. Assembly Lubricate the rotating parts in fresh engine oil. Fit the outer and inner rotors into the oil pump body. Install the oil pump dowel pin.
  • Page 361 5.Engine MXU 550i Install the oil pump cover. Install the oil pump cover screw and tighten it to specification with a #2 Phillips screwdriver. 6-140...

  • Page 362: Installation

    5.Engine MXU 550i ITEM kgf-m ft-lb Oil pump screw Slide the oil pump shaft into the oil pump. Installation Fit the oil pump into place with the arrow pointing up. 6-141...
  • Page 363 5.Engine MXU 550i Insert the two oil pump mounting bolts and tighten them securely Turn the oil pump shaft and make sure it turns smoothly. Install the two oil pump shaft holder dowel pins. 6-142...
  • Page 364 5.Engine MXU 550i Fit the oil pump shaft holder into place. Install the oil pump shaft holder bolt. Do not tighten, yet. 6-143...
  • Page 365 5.Engine MXU 550i Fit the oil pump sprocket and chain into place. Engage the chain to its drive sprocket on the crankshaft. Fit the oil pump sprocket onto the oil pump shaft. Install the new snap ring with snap ring pliers. Install the oil separator and the two mounting bolts.
  • Page 366 5.Engine MXU 550i Tighten the oil pump holder shaft bolt and two oil separator mounting bolts securely with an 8 mm socket. Tighten the bolts evenly in a crisscross pattern. Fit the oil pump chain guide into place. 6-145...
  • Page 367 5.Engine MXU 550i Install the two oil pump chain guide bolts and tighten them securely with an 8 mm socket. Install the flywheel. See the Flywheel topic for more information. Install the left crankcase cover. See the Generator Cover topic fore more information. Install the recoil starter.

  • Page 368: Cam Chain

    5.Engine MXU 550i Cam Chain SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove the following components: • Cylinder Head • Cylinder and Piston • Recoil Starter Cover • Generator Cover • Flywheel • Oil Pump - Oil pump sprocket and chain There are two cam chain guides that are mounting on pivot bolts.
  • Page 369 5.Engine MXU 550i Remove the two cam chain guide pivot bolts with an 8 mm Allen. 6-148...
  • Page 370 5.Engine MXU 550i Inspect the cam chain guides for excessive wear and damage. Replace the guides as needed. Remove the cam chain. Inspect the cam chain for kinking, fatigue, and damage. Replace the cam chain as needed. 6-149...
  • Page 371 5.Engine MXU 550i Installation Fit the cam chain into place. Of the two sprockets on the crankshaft the cam chain's timing sprocket is the inner sprocket. The outer sprocket is the oil pump drive chain sprocket. Install the two cam chain guides. The larger guide is on the tensioner side. 6-150...
  • Page 372 5.Engine MXU 550i Install the two cam chain guide pivot bolts and tighten them to specification with an 8 mm Allen. ITEM kgf-m ft-lb Cam chain guide pivot bolt Install the following components: • Oil Pump - Oil pump sprocket and chain •...

  • Page 373: Engine Removal

    5.Engine MXU 550i Engine Removal SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Remove these components Component Topic Seat Seat Battery Battery Front cover Front Cover Side Covers Side Covers Fuel tank and shield Fuel Tank Rack Racks Front fender Front Fender...
  • Page 374 5.Engine MXU 550i Disconnect the crankcase breather hose from the cylinder head cover on the MXU 550i models. Free the breather hose from the bevel gear cover on the MXU 550i models. 6-153...
  • Page 375 5.Engine MXU 550i Disconnect the air inlet hose from the PAIR valve on vehicles equipped with an air injection emissions system. Push in the spring and unplug the WTS sensor connector. Trace the wires up from the generator cover. Unplug the 4-pin stator connector. 6-154...
  • Page 376 5.Engine MXU 550i Unplug the 2-pin ignition pulse generator / crank position sensor connector. Trace the wires up from the gear position switch. Unplug the gear position switch connector. 6-155...
  • Page 377 5.Engine MXU 550i Unplug the connector from the speed sensor. Pull back the rubber cover from the starter motor terminal. Loosen the starter motor terminal nut with a 10 mm socket and free the lead from the terminal. Remove the starter motor mounting bolt with the ground wire with an 8 mm socket.
  • Page 378 5.Engine MXU 550i Squeeze the clamp on the air bleed hose and slide it back. Loosen the coolant hose clamp with a #2 Phillips screwdriver. Free the hoses from the WTS housing. Loosen the bypass (smaller) and lower radiator hose (larger) clamp with a #2 Phillips screwdriver.
  • Page 379 5.Engine MXU 550i Lift the front of the engine and move it forward to disconnect the rear propeller shaft. Remove the rear propeller shaft. 6-158...
  • Page 380 5.Engine MXU 550i Slide the engine back. Disconnect the front propeller shaft. Note: Do note lose the propeller shaft springs. 6-159...
  • Page 381 5.Engine MXU 550i Lift the rear of the engine and tilt the engine forward to lower the cylinder head. Guide the engine out of the left side of the frame. To install the engine. See the Engine Installation topic for more information. 6-160...

  • Page 382: Engine Installation

    5.Engine MXU 550i Engine Installation SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Lubricate the splines of the propeller shafts and final gear pinion shafts with a lightweight lithium-soap based grease. The propeller shaft springs fit between propeller shafts and the final drive pinion shafts.
  • Page 383 5.Engine MXU 550i Tilt the engine to lower the cylinder head and guide the engine into the frame. Bring the engine in from the left side of the frame. Install the front propeller shaft and slide the engine forward. Install the rear propeller shaft. 6-162...
  • Page 384 5.Engine MXU 550i Adjust the engine so that the engine mounts line up correctly. Insert the engine mounting bolts from the right side and thread on the nuts. Hold the engine mounting bolts and torque the nuts to specification. Torque Item Thread dia.
  • Page 385 5.Engine MXU 550i Connect the air inlet hose to the PAIR valve on vehicles equipped with an air injection emissions system. Connect the coolant hoses to the water pump as shown. Tighten the coolant hose clamps securely with a #2 Phillips screwdriver. 6-164...
  • Page 386 5.Engine MXU 550i Connect the air bleed hose and thermostat hose to the WTS housing. Secure the hoses with the clamps. Plug in the WTS sensor connector. 6-165...
  • Page 387 5.Engine MXU 550i Install the ground lead with the starter motor mounting bolt. Tighten the starter motor mounting bolts to specification with an 8 mm socket. Connect the lead to the starter motor. Tighten the nut securely with a 10 mm socket. Move the rubber cover into place over the terminal.
  • Page 388 5.Engine MXU 550i Plug in the gear position switch connector. Plug in the 4-pin stator connector. Plug in the 2-pin ignition pulse generator / crank position sensor connector. 6-167...
  • Page 389 5.Engine MXU 550i Connect the crankcase breather hose to the cylinder head cover on the MXU 550i models. Secure the hose with the clamp. Install the spark plug cap onto the spark plug. Install these components Component Topic Drive selector Drive Mode Selector CVT cooling ducts CVT Cooling Ducts...
  • Page 390 5.Engine MXU 550i Fill the coolant Coolant Mudguards Mudguards and Footrests Side covers Side Covers Front cover Front Cover Racks Racks Battery Battery Seat Seat 6-169...

  • Page 391: Output Shaft And Bevel Gear

    5.Engine MXU 550i Output Shaft and Bevel Gear SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove the engine. See the Engine Removal topic for more information. Bevel Gear Cover Remove the five bevel gear case cover bolts with an 8 mm socket. 6-170...
  • Page 392 5.Engine MXU 550i Remove the bevel gear cover. Remove the gasket and the two bevel gear cover dowel pins. Inspect the oil sight glass and replace it as needed. 6-171...
  • Page 393 5.Engine MXU 550i Output Shaft and Bevel Gears Unstake the output shaft nut with a chisel and a hammer. Insert the rear propeller shaft and hold it to keep the output shaft from turning. 6-172...
  • Page 394 5.Engine MXU 550i Loosen the output shaft nut with a 26 mm socket. Remove output shaft nut. 6-173...
  • Page 395 5.Engine MXU 550i Remove the rear propeller shaft coupler from the engine. Tap the output shaft forward with a rubber mallet. 6-174...
  • Page 396 5.Engine MXU 550i Move the output shaft forward so that the driven bevel gear can be removed. Remove the driven bevel gear and shim. 6-175...
  • Page 397 5.Engine MXU 550i Slide the output shaft out of the engine. Unstake drive bevel gear nut with a chisel and a hammer. Remove the belt case cover. See the CVT Removal topic. Hold the driven pulley with a Y-type holder. Special Tool - Y-Type Holder: A120E00056 6-176...
  • Page 398 5.Engine MXU 550i Loosen the drive bevel gear nut with a deep well 26 mm socket. Remove the drive bevel gear nut. 6-177...
  • Page 399 5.Engine MXU 550i Slide off the drive bevel gear. Remove the drive bevel gear shim. 6-178...

  • Page 400: Seals And Bearings

    5.Engine MXU 550i Seals and Bearings Inspect the propeller shaft oil seals for leaks and damage. Inspect the bearings by turning them with a finger. Replace the bearings if they do not turn smoothly. Remove the seals with a seal pick if needed. Replace the oil seals with new items if they are removed.
  • Page 401 5.Engine MXU 550i If the rear bearing needs to be replaced the lock nut must be removed. Remove the lock nut with the special tool. Special Tool - Nut Wrench: A120E00066 6-180...
  • Page 402 5.Engine MXU 550i Remove the rear bearing with a suitable bearing puller. Special Tool- Bearing Puller: A120E00037 Drive in the new bearing with a suitable driver that is the same outside diameter as the bearing. The manufactures markings on the bearing must face out. Special Tool - Bearing Driver: A120E00014 6-181...
  • Page 403 5.Engine MXU 550i Install the lock nut with the special tool. Special Tool - Nut Wrench: A120E00066 Torque the lock nut to specification with the special tool. ITEM kgf-m ft-lb Driven pulley nut 79.2 6-182...
  • Page 404 5.Engine MXU 550i If the front bearing is to be replaced the snap ring must be removed. Remove the bearing snap ring with snap ring pliers. 6-183...
  • Page 405 5.Engine MXU 550i Remove the bearing with a suitable bearing puller. Special Tool- Bearing Puller: A120E00037 Drive in the new bearing with a suitable driver that is the same outside diameter as the bearing. The manufactures markings on the bearing must face out. Special Tool - Bearing Driver: A120E00014 6-184...
  • Page 406 5.Engine MXU 550i Install a new snap ring with snap ring pliers. Lubricate the lips of the new oil seals with fresh engine oil. Press in the new seals with a suitable driver with the same outside diameter as the seals. 6-185...
  • Page 407 5.Engine MXU 550i Inspection Inspect the propeller shaft couplers for wear and damage. Inspect the bevel gears for wear and damage. 6-186...
  • Page 408 5.Engine MXU 550i Inspect the output shaft for damage and wear. Bevel Gear Backlash Remove the bevel gear cover. The bevel gears must be installed as normal. Set a dial gauge on the driven bevel gear as shown. Measure the backlash by turning the rear propeller shaft in each direction, reading the total backlash on the dial gauge.
  • Page 409 5.Engine MXU 550i Bevel gear backlash 0.03 - 0.15 mm (0.001 - 0.006 in) See the chart for appropriate shim thickness. Backlash Shim Adjustment under 0.03 mm (0.001 in) Reduce shim thickness 0.03 - 0.15 mm (0.001 - 0.006 in) Correct shim thickness over 0.15 mm (0.006 in) Increase shim thickness...
  • Page 410 5.Engine MXU 550i • Rotate the rear propeller shaft several turns in both directions. • Remove the driven bevel gear and inspect the coated teeth of the drive bevel gear. The tooth contact pattern should be as shown the examples 1, 2 and 3. 1 - Incorrect (contact at tooth top) 2 - Correct 6-189...
  • Page 411 5.Engine MXU 550i • If tooth contact is found to be correct (example 2) complete the installation. • If tooth contact is found to be incorrect (examples 1 and 3), the shim thickness between the drive bevel gear and driven bevel gear must be changed and the tooth contact rechecked until correct.

  • Page 412: Installation

    5.Engine MXU 550i Installation Output Shaft and Bevel Gears Install the drive bevel gear shim. Slide on the drive bevel gear. 6-191...
  • Page 413 5.Engine MXU 550i Lubricate the new drive bevel gear lock nut threads with engine oil. Thread on the new drive bevel gear lock nut. Hold the driven pulley with a Y-type holder. Special Tool - Y-Type Holder: A120E00056 Tighten the drive bevel gear nut to specification with a deep well 26 mm socket. 6-192...
  • Page 414 5.Engine MXU 550i ITEM kgf-m ft-lb Drive bevel gear lock nut 100.8 Stake the drive bevel gear lock nut with a chisel and a hammer. Slide the output shaft into the engine as shown. 6-193...
  • Page 415 5.Engine MXU 550i Fit the driven bevel gear and shim into place. Guide the output shaft through the driven bevel gear and shim. 6-194...
  • Page 416 5.Engine MXU 550i The output shaft must protrude through the seal. Install the rear propeller shaft coupler. 6-195...
  • Page 417 5.Engine MXU 550i Lubricate the new output shaft nut threads with engine oil. Install the new output shaft nut. Insert the forward propeller shaft and hold it to keep the output shaft from turning. 6-196...
  • Page 418 5.Engine MXU 550i Tighten the output shaft nut to specification with a 26 mm socket. ITEM kgf-m ft-lb Driven bevel gear lock nut 100.8 Stake the output shaft nut with a chisel and a hammer. 6-197...
  • Page 419 5.Engine MXU 550i Bevel Gear Cover Install two bevel gear cover dowel pins and a new gasket. Fit the bevel gear cover into place. 6-198...
  • Page 420 5.Engine MXU 550i Install the five bevel gear case cover bolts. Tighten the bolts evenly and securely with an 8 mm socket. Install the engine. See the Engine Installation topic for more information. 6-199...

  • Page 421: Crankcase

    5.Engine MXU 550i Crankcase SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Splitting Remove the engine from the frame. See the Engine Removal topic for more information. Remove the following engine components: • Cylinder Head Cover • Camshaft •...
  • Page 422 5.Engine MXU 550i Loosen the shift cam stopper plug with a 14 mm socket. Remove the stopper plug, washer, spring, and stopper ball. 6-201...
  • Page 423 5.Engine MXU 550i Inspect the shift cam stopper components and replace them as needed. Remove the shift arm bolt with a 10 mm socket. 6-202...
  • Page 424 5.Engine MXU 550i Remove the shift arm from the shift shaft. Remove the gear position indicator switch bolt with an 8 mm socket. Remove the gear position indicator switch. Note its position so that it can be returned to its original orientation.
  • Page 425 5.Engine MXU 550i Remove the four bolts from the CVT side of the crankcase. There are three bolts on the clutch end, and one bolt on the other end. Remove the bolts with an 8 mm socket. Loosen the 15 generator side crankcase bolts evenly and in a crisscross pattern. Remove the generator side crankcase bolts with an 8 mm socket.
  • Page 426 5.Engine MXU 550i Utilize the pry points and separate the halves of the crankcases. Remove the two dowel pins from the crankcase. Remove the old crankcase gasket material. To remove the crankshaft and balancer see the Crankshaft topic. To remove the transmission see the Transmission Removal topic.

  • Page 427: Oil Relief Valve

    5.Engine MXU 550i Oil Relief Valve The oil relief valve is located in the crankcase. If it is necessary, remove the oil pipe; Remove the two bolts, washers (on the oil pipe), oil pipe and washers (under oil pipe). 6-206...
  • Page 428 5.Engine MXU 550i Remove the oil relief valve from the crankcase. Push in on the oil relief valve piston and make sure it moves smoothly. Replace it if it sticks or refuses to move. 6-207...
  • Page 429 5.Engine MXU 550i Discard the O-ring and replace it with a new item. Apply fresh engine oil to the new O-ring. Fit the oil relief valve into place in the crankcase. 6-208...
  • Page 430 5.Engine MXU 550i Assembly Make sure the crankcase mating surfaces are clean. Install the inner washers on the right crankcase. Install the oil pipe with the thick side face upward. Apply clean engine oil to the bolts, then install the outer washers and two bolts. Tighten the two bolts to the specified torque.
  • Page 431 5.Engine MXU 550i Apply Threebond 1215 or other equivalent sealant to the crankcase mating surface. Do not allow the sealant to get into oil passages or bearings. The crankcases must be joined in a few minutes or the sealant will not function correctly. Fit the generator side crankcase half onto the CVT crankcase half.
  • Page 432 5.Engine MXU 550i Insert the 15 generator side crankcase bolts. Tighten the bolts evenly and in a crisscross pattern. Torque the 15 generator side crankcase bolts to specification with an 8 mm socket. ITEM kgf-m ft-lb Crankcase bolt Install the four CVT side of the crankcase bolts and tighten them to specification with an 8 mm socket.
  • Page 433 5.Engine MXU 550i ITEM kgf-m ft-lb Crankcase bolt Install a new O-ring to the gear position indicator switch if needed. Lubricate the O-ring with fresh engine oil. Install the gear position indicator switch. Install the gear position indicator switch bolt and tighten it securely with an 8 mm socket. 6-212...
  • Page 434 5.Engine MXU 550i Install the shift arm to the shift shaft. Install the shaft arm bolt and tighten it securely with a 10 mm socket. Use a new sealing washer with the shift cam stopper plug. 6-213...
  • Page 435 5.Engine MXU 550i Install the stopper plug, washer, spring, and stopper ball. Tighten the stopper plug to specification with a 14 mm socket. ITEM kgf-m ft-lb Shift cam stopper plug Make sure the engine shafts turn properly. 6-214...
  • Page 436 5.Engine MXU 550i Install the following engine components: • Starter Motor • Clutch Installation • CVT Installation • Output Shaft and Bevel Gear • Belt Case Cover • Cam Chain • Oil Pump • Flywheel • Generator Cover • Recoil Starter Cover •...

  • Page 437: Crankshaft

    5.Engine MXU 550i Crankshaft SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Split the crankcases. See the crankcase Crankcase topic for more information. Remove the transmission. See the Transmission Removal topic for more information. Remove the crankshaft and balancer shaft together. Inspection 6-216...
  • Page 438 5.Engine MXU 550i Inspect the balancer shaft for wear and damage. Inspect the crankshaft for wear or damage. Turn the crank bearings with a finger and make sure they turn smoothly. Replace the crankshaft if the bearings are faulty. Measure the inside diameter of the small end of the connecting rod. Item Standard Service Limit...
  • Page 439 5.Engine MXU 550i Place the crankshaft on V-blocks and measure the runout on each side with a dial gauge. Check the side clearance of the big end of the connecting rod with a feeler gauge. Item Standard mm (in) Service Limit Not USA 0.01 - 0.4 (0.002 - 0.6 (0.024)

  • Page 440: Installation

    5.Engine MXU 550i Installation Lubricate the crankshaft and balancer bearings with fresh engine oil. Fit the crank and balancer shafts into the crankcase together. The line on the balancer sprocket must align with the line on the crankshaft. Install the transmission. See the Transmission Installation topic for more information.

  • Page 441: Transmission Removal

    5.Engine MXU 550i Transmission Removal SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Split the crankcases. See the Crankcase topic for more information. Remove the shift shaft. Remove the transmission guide bar. 6-220...
  • Page 442 5.Engine MXU 550i Remove the upper and lower shift forks. Remove the shift cam. Remove the transmission shafts together from the crankcase. To disassemble the transmission shafts see the Transmission Shafts topic for more information. 6-221...
  • Page 443 5.Engine MXU 550i Remove the stopper lever bolt and washer with a 6 mm Allen wrench. Remove the stopper lever and spring. Remove the crankshaft and balancer shaft together. See the Crankshaft for more information. 6-222...
  • Page 444 5.Engine MXU 550i Place the nut that was removed from the driven pulley back onto the transmission drive shaft to protect the threads and begin to press the shaft out. Remove the nut before it reaches the oil seal as it will not fit through. Remove the shaft. If the bearing comes out with the transmission drive shaft press it off as shown.
  • Page 445 5.Engine MXU 550i If the transmission drive shaft bearing does not come out with the shaft and needs to be replaced; remove it with a bearing puller. See the Crankcase Bearings topic for more information. Note: Always replace the bearing if it is removed from the crankcase. Inspect the transmission drive shaft oil seal and replace if needed.
  • Page 446 5.Engine MXU 550i If it is necessary to remove the stopper lever shaft use a 19 mm socket to remove the nut and washer on the other side. 6-225...
  • Page 447 5.Engine MXU 550i Upper Shift Fork Disassembly Remove the snap ring with snap ring pliers. Remove the washer. 6-226...
  • Page 448 5.Engine MXU 550i Remove the shift fork and spring. Remove the snap ring with snap ring pliers. Remove the washer and cam pawl. 6-227...
  • Page 449 5.Engine MXU 550i Inspection Check the stopper lever pawl for bends, damage or wear. Inspect the spring for cracks or damage. Check the transmission drive shaft gear teeth for blue discoloration, pitting or wear. 6-228...
  • Page 450 5.Engine MXU 550i Measure the guide bar runout. Replace the bar if it is out of specification. Item Service Limit Guide Bar Runout 0.03 mm (0.0012 in) Inspect the upper shift fork cam followers, shift fork pawl and spring. If there is any damage or excessive wear replace the components as a set.
  • Page 451 5.Engine MXU 550i Inspect the upper shift fork cam followers and shift fork pawl. If there is any damage or excessive wear replace the part. Check the shift cam grooves and shift cam gear. Check for wear and damage and replace if needed.
  • Page 452 5.Engine MXU 550i Inspect shift shaft gear and shift shaft for damage, bends or wear. Check the return spring for fatigue or damage. Replace the parts if needed. Inspect the transmission bearings. See the Crankcase Bearings topic for more information. To assemble the transmission see the Transmission Installation topic for more information.

  • Page 453: Transmission Shafts

    5.Engine MXU 550i Transmission Shafts SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Remove the transmission shafts from the transmission. See the Transmission Removal topic for more information. Disassembly When disassembling the transmission shafts be sure to keep track of the order and orientation of the parts as they come apart.
  • Page 454 5.Engine MXU 550i Countershaft Remove the washer. Remove the high drive gear. Remove the bushing and washer. 6-233...
  • Page 455 5.Engine MXU 550i Remove the high/low gear shifter. Remove the snap ring with snap ring pliers. Remove the washer and low drive gear. 6-234...
  • Page 456 5.Engine MXU 550i On the other side of the countershaft; Remove the snap ring with snap ring pliers. Remove the stopper wheel. Remove the snap ring with snap ring pliers. 6-235...
  • Page 457 5.Engine MXU 550i Remove the reverse gear shifter. Remove the snap ring with snap ring pliers. Remove the washer and reverse drive gear. 6-236...
  • Page 458 5.Engine MXU 550i Inspect the countershaft, gear teeth and mated dogs. Check for blue discoloration, pitting or wear. Check for rounded edges, cracks or other damage. Replace as needed. Bevel Gear Drive Shaft Remove the thick washer. Remove the reverse gear. 6-237...
  • Page 459 5.Engine MXU 550i Remove the thin washer. Inspect the gear teeth. Check for blue discoloration, pitting or wear. Replace as needed. 6-238...
  • Page 460 5.Engine MXU 550i Inspect the needle bearing in the reverse gear. Check for wear or damage. Replace as needed. Assembly Use new snap rings when assembling the transmission shaft components. Install the snap ring (and thrust washer) so that the sharp edge is facing away from the gear that is putting thrust against it.
  • Page 461 5.Engine MXU 550i Also, make sure the snap rings are fully seated in their grooves as shown. Spread the new snap rings only enough to slide them down the shaft and into their grooves. Note: Coat the gears and shafts lightly with fresh engine oil before installation. Bevel Gear Drive Shaft Install the thin washer on the drive shaft.
  • Page 462 5.Engine MXU 550i Install the reverse gear. Install the thick washer. Countershaft 6-241...
  • Page 463 5.Engine MXU 550i Install the reverse drive gear and washer on the proper side of the countershaft. Install the snap ring with snap ring pliers. Install the reverse gear shifter. 6-242...
  • Page 464 5.Engine MXU 550i Install the snap ring with snap ring pliers. Install the stopper wheel. Install the snap ring with snap ring pliers. 6-243...
  • Page 465 5.Engine MXU 550i On the other side of the countershaft; Install the low drive gear and washer. Install the snap ring with snap ring pliers. Install the high/low gear shifter. 6-244...
  • Page 466 5.Engine MXU 550i Install the washer and bushing. Install the high drive gear. Install the washer. To install the transmission see the Transmission Installation topic. 6-245...

  • Page 467: Transmission Installation

    5.Engine MXU 550i Transmission Installation SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Upper Shift Fork Assembly Install the cam pawl on the shaft and be sure to align the marks as shown. 6-246...
  • Page 468 5.Engine MXU 550i Install the washer. Install the snap ring with snap ring pliers. Install the spring. 6-247...
  • Page 469 5.Engine MXU 550i Install the shift fork on the shaft and be sure to align the marks as shown. Install the washer. 6-248...

  • Page 470: Installation

    5.Engine MXU 550i Install the snap ring with snap ring pliers. Installation Install the stopper lever shaft if it was removed. Install the shaft on the outside and the nut with washer on the inside. Carefully hold the stopper lever shaft with a wrench if necessary. Tighten the bolt to specification with a 19 mm socket.
  • Page 471 5.Engine MXU 550i Apply clean engine oil to a new drive shaft oil seal lip. Install the transmission drive shaft oil seal. Use a suitable driver that is the same outside diameter as the seal. Install the stopper lever and spring on the shaft. Note: Hook the spring onto the hook part of the stopper lever, squeeze the spring in to the groove of the left crankcase.
  • Page 472 5.Engine MXU 550i Install the washer and a new stopper lever bolt. Hold the shaft nut on the other side. Tighten the bolt to specification with a 6 mm Allen wrench. Item kgf-m ft-lb Stopper lever bolt 6-251...
  • Page 473 5.Engine MXU 550i Install the transmission drive shaft bearing with a bearing driver. Special Tool- Bearing Driver: A120E00014 Note: Apply clean engine oil to the transmission drive shaft, countershaft and drive shaft. Carefully press in the transmission drive shaft. 6-252...
  • Page 474 5.Engine MXU 550i Install the transmission shafts together into the crankcase. Apply clean engine oil to the shift cam and install it. 6-253...
  • Page 475 5.Engine MXU 550i Apply clean engine oil to the upper and lower shift forks and pawls. Install the lower gearshift fork into the lower shifter shift groove on the countershaft with its “LDB5” mark facing down. Fit the lower shift fork guide pin into the groove on the shift cam. 6-254...
  • Page 476 5.Engine MXU 550i Install the upper gearshift fork into the upper shifter shift groove on the countershaft with its “LDB5” mark facing up. Fit the upper shift fork guide pin into the groove on the shift cam. Apply clean engine oil to the transmission guide bar and install it. Install the shift shaft.
  • Page 477 5.Engine MXU 550i Install the crankshaft and balancer shaft together (if they were removed). See the Crankshaft for more information. Assemble the crankcases. See the Crankcase topic for more information. 6-256...

  • Page 478: Crankcase Bearings

    5.Engine MXU 550i Crankcase Bearings SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Inspection Inspect the crankcase bearings. Turn the bearings with a finger. They should turn freely without noise or binding, but also without excessive play. Make sure the outer races of the bearings are secure in the crankcase.
  • Page 479 5.Engine MXU 550i Replacement Place the new bearing in the freezer at least a half hour before you plan to install them. Remove the bearings with a suitable bearing puller. Special Tool - Bearing Puller: A120E00037 6-258...
  • Page 480 5.Engine MXU 550i To replace the drive shaft bearing first remove the set plates. Remove the set plate bolts with a 6 mm Allen. Install the bearing set plates after the bearing has been replaced and tighten new bolts securely with a 6 mm Allen. Replace the oil seal if its bearing is to be replaced.

  • Page 481: Cooling System

    6.Cooling System MXU 550i Cooling System This chapter covers the location and servicing of the external components for the KYMCO MXU 550i models. Coolant ........................6-3 Pressure Testing ....................6-11 Radiator ........................ 6-13 Thermostat ......................6-24 Water Pump ......................6-30...

  • Page 482: Troubleshooting

    6.Cooling System MXU 550i TROUBLESHOOTING Engine temperature too high • Faulty temperature gauge or sensor • Faulty radiator cap • Air in system • Faulty thermostat (stuck closed) • Insufficient coolant • Passages blocked in hoses or water jacket • Clogged radiator fins •...

  • Page 483: Coolant

    6.Cooling System MXU 550i Coolant SAFETY FIRST: Antifreeze is highly toxic and can kill pets and animals if drank. Do not leave coolant where animals (including children) can get to it. WARING:Removing the radiator cap while the engine is hot can allow the coolant to spray out, seriously scalding you.
  • Page 484 6.Cooling System MXU 550i Check the coolant when cold. The coolant level should be between the two indicator lines. If the level is low, remove the reserve tank cap (1) and fill the tank to the “FULL” level line with 1:1 mixture of distilled water and antifreeze Caution: Using coolant with silicate inhibitors may cause premature wear of water pump seals or blockage of radiator passages.
  • Page 485 6.Cooling System MXU 550i The radiator filler cap is located beside the coolant reservoir tank and steering shaft. Remove the radiator cap by pushing down and turning it. Use a shop towel to hold the cap. Remove the radiator cap in two stages. Allow any built up pressure to vent, then open the cap all the way and remove it.
  • Page 486 6.Cooling System MXU 550i The drain bolt is located on the water pump. Some models may not be equipped with a drain bolt. In this case remove the small bypass coolant hose from the water pump and allow the coolant to drain. Place a drain pan underneath the water pump and remove the drain plug using an 8 mm socket.
  • Page 487 6.Cooling System MXU 550i Be prepared the coolant will spurt out quickly. Allow the coolant to fully drain. Install the drain plug with a new sealing washer and tighten it securely after the cooling system has been drained. Return the bypass hose to the water pump if it was removed and tighten the clamp.
  • Page 488 6.Cooling System MXU 550i To drain the reservoir tank remove the two mounting bolts. Disconnect the siphon hose (A) from the filler cap neck. and drain the reservoir tank. Install the tank and tighten the two mounting bolts securely. Connect the siphon hose (A) to the filler cap neck and secure it with the clamp.
  • Page 489 6.Cooling System MXU 550i COOLANT GRAVITY CHART Temperature °C Coolant Concentration 1.009 1.009 1.008 1.008 1.007 1.006 1.005 1.003 1.001 0.009 0.997 1.018 1.107 1.017 1.016 1.015 1.014 0.013 1.011 1.009 1.007 1.005 1.028 1.027 1.026 1.025 1.024 1.022 1.020 1.018 1.016 1.014 1.012 1.036 1.035 1.034 1.033 1.031 1.029 1.027 1.025 1.023 1.021 1.019 1.045 1.044 1.043 1.042 1.040 1.038 1.036 1.034 1.031 1.028 1.025 1.053 1.051 1.051 1.049 1.047 1.045 1.043 1.041 1.038 1.035 1.032...
  • Page 490 6.Cooling System MXU 550i Fill the reservoir with coolant to the FULL line. Slowly pour the new coolant into the radiator filler neck until it reaches the bottom of the neck. With the reservoir cap and the radiator cap off, start the engine and let it run for several minutes.

  • Page 491: Pressure Testing

    6.Cooling System MXU 550i Pressure Testing SAFETY FIRST: Antifreeze is highly toxic and can kill pets and animals if drank. Do not leave coolant where animals (including children) can get to it. SAFETY FIRST: Protective gloves and eyewear are recommended at this point. CAUTION: Never remove the radiator cap when the engine is hot.
  • Page 492 6.Cooling System MXU 550i Remove the radiator cap by pushing down and turning it. Use a shop towel to hold the cap. Remove the radiator cap in two stages. Allow any built up pressure to vent, then open the cap all the way and remove it. When checking the cooling system for leaks you will need a pressure tester.

  • Page 493: Radiator

    6.Cooling System MXU 550i Radiator SAFETY FIRST: Antifreeze is highly toxic and can kill pets and animals if drank. Do not leave coolant where animals (including children) can get to it. WARING:Removing the radiator cap while the engine is hot can allow the coolant to spray out, seriously scalding you.
  • Page 494 6.Cooling System MXU 550i Pressure Testing See the Pressure Testing topic. Removal Remove these components Component Topic Front rack Racks Seat Seat Front cover Front Cover Side covers Side Covers Fuel tank cover Fuel Tank Front mudguard fasteners Mudguards and Footrests Front fender Front Fender Drain the coolant...
  • Page 495 6.Cooling System MXU 550i The MXU 700i radiator has three hoses; a water pump hose (lower right), a filler neck hose (upper right), and a thermostat hose (upper left). The MXU 500 also has a small air bleed hose that connects to the radiator. Loosen the clamps and free the hoses from the radiator. Unplug the radiator fan connector.
  • Page 496 6.Cooling System MXU 550i The radiator cowling is held on with four bolts. Remove the two upper and two lower radiator cowling bolts. 6-16...
  • Page 497 6.Cooling System MXU 550i There are three relays that are ride on the radiator mounts. Free the relays from the fingers on the radiator mounts. Remove the two radiator mounting bracket to frame bolts. Lift up the radiator and free the studs from the rubber grommets Remove the radiator and bracket from the frame.
  • Page 498 6.Cooling System MXU 550i To remove the radiator fan remove the four nuts. To remove the upper and lower mounting brackets take out the bolts on the corners. To remove the upper front cooling duct remove the bolt with a 10 mm socket. Inspection Radiator Fins Inspect the radiator fins for damage and clogging.

  • Page 499: Radiator Fan

    6.Cooling System MXU 550i Check the radiator for any bent or damaged fins. Use a small flat blade screwdriver to straighten them out, but be careful not to puncture the radiator. Radiator Fan Jump a 12 volt battery to the fan connector and make sure the radiator fan operates. To inspect the water temperature sensor (WTS) see the Fuel Injection Sensors topic.
  • Page 500 6.Cooling System MXU 550i Install the upper and lower radiator mounting brackets and tighten the corner bolts securely. Install the radiator fan and tighten the nuts securely. Fit the radiator into place. Guide the studs on the bottom radiator mounting bracket into the rubber grommets. 6-20...
  • Page 501 6.Cooling System MXU 550i Install the two radiator mounting bracket to frame bolts. Return the three relays to their mounts on the upper radiator mounting bracket. 6-21...
  • Page 502 6.Cooling System MXU 550i Install the two upper and two lower radiator cowling bolts and tighten them securely. Plug in the radiator fan connector. 6-22...
  • Page 503 6.Cooling System MXU 550i The MXU 550 also has an air bleed hose that connects to the radiator. Connect the radiator hoses and tighten the clamps securely. Install these components Component Topic Front bumper Front Bumper Upper front cooling duct for the CVT CVT Cooling Ducts Fuel tank Fuel Tank...

  • Page 504: Thermostat

    6.Cooling System MXU 550i Thermostat SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove these components Component Topic Front rack Racks Seat Seat Front cover Front Cover Side covers Side Covers Fuel tank cover Fuel Tank Front mudguard fasteners Mudguards and Footrests Front fender...
  • Page 505 6.Cooling System MXU 550i Remove the thermostat housing bolts with an 8 mm socket. Separate the housing cover from the thermostat housing. 6-25...
  • Page 506 6.Cooling System MXU 550i Remove the O-ring from the housing cover. Remove the thermostat. 6-26...
  • Page 507 6.Cooling System MXU 550i Inspection Inspect the thermostat valve at room temperature, if the valve is open the thermostat is defective and needs to be replaced. Also, replace the thermostat if its seal ring is in poor condition. To check the thermostat opening temperature, fill a pan with tap water and suspend the thermostat with a piece of wire, completely immersing it in the water making sure the thermostat does not touch the pan.
  • Page 508 6.Cooling System MXU 550i Installation Install the thermostat so its air bleed hole faces up and aligns with the tab in the housing. Install a new O-ring in the housing cover. 6-28...
  • Page 509 6.Cooling System MXU 550i Join the housing cover with the thermostat housing. Install the thermostat housing bolts and tighten them securely with an 8 mm socket. Fill the coolant if necessary. See the Coolant topic for more information. Install the inner fender. See the Inner Fender topic for more information. 6-29...

  • Page 510: Water Pump

    6.Cooling System MXU 550i Water Pump SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Mechanical Seal Inspection Remove the right mudguard. See the Mudguards and Footrests topic for more information. Inspect the telltale hole in the water pump cover for signs of coolant leaking. If there is coolant coming from this hole the mechanical seal is compromised and the water pump must be replaced.
  • Page 511 6.Cooling System MXU 550i Loosen the water pump to cylinder coolant hose clamp with a #2 Phillips screwdriver. Free the cylinder coolant hose fro the water pump. Loosen the bypass (smaller) and lower radiator hose (larger) clamp with a #2 Phillips screwdriver.
  • Page 512 6.Cooling System MXU 550i The water pump has two mounting bolts (M), two cover bolts (C), and a drain bolt (D). Go ahead and loosen the cover bolts while the water pump is installed if the cover is to be removed.
  • Page 513 6.Cooling System MXU 550i Remove the water pump bolts with an 8 mm socket. Remove the water pump cover. 6-33...
  • Page 514 6.Cooling System MXU 550i Remove the water pump O-ring and discard it. Remove the water pump body from the engine. Discard the water pump body O-ring. Replace it with a new item on installation. Turn the water pump shaft and make sure it turns smoothly without binding. 6-34...
  • Page 515 6.Cooling System MXU 550i Inspect the water pump impeller. Replace the water pump as a whole if the impeller or shaft is damaged. Installation Install a new O-ring to the water pump body. Apply fresh engine oil to the O-ring. 6-35...
  • Page 516 6.Cooling System MXU 550i Fit the water pump body into place. Guide the water pump shaft groove onto the end of the oil pump shaft. 6-36...
  • Page 517 6.Cooling System MXU 550i Install a new O-ring into the groove on the water pump cover. Fit the water pump cover into place. 6-37...
  • Page 518 6.Cooling System MXU 550i The water pump has two mounting bolts (M), two cover bolts (C), and a drain bolt (D). Install the mounting bolts before the cover bolts. Install the water pump mounting bolts and cover bolts. The mounting bolts are gold colored and longer than the silver cover bolts.
  • Page 519 6.Cooling System MXU 550i Tighten the water pump bolts to specification with an 8 mm socket. ITEM kgf-m ft-lb Water pump bolt Connect the bypass hose (smaller) and lower radiator hose (larger) to the water pump. Install the clamps. Tighten the clamps securely with a #2 Phillips screwdriver. 6-39...
  • Page 520 6.Cooling System MXU 550i Connect the cylinder coolant hose to the water pump. Install the hose clamp and tighten it securely with a #2 Phillips screwdriver. Fill the engine oil. See the Engine Oil topic for more information. Fill the coolant and bleed the cooling system. See the Coolant topic for more information.

  • Page 521: Cvt Continuously Variable Transmission

    7.CVT MXU 550i CVT Continuously Variable Transmission This chapter covers the location and servicing of the CVT components for the KYMCO MXU 550i models. CVT Cooling Ducts ..........................7-3 Belt Case Cover ..........................7-8 CVT Removal ........................... 7-16 CVT Installation ..........................7-30 Clutch Removal..........................

  • Page 522: Troubleshooting

    7.CVT MXU 550i TROUBLESHOOTING Engine starts but vehicle won't move • Worn drive belt • Broken ramp plate • Worn or damaged clutch lining • Broken driven face spring Engine stalls or vehicle creeps • Broken clutch weight spring Lack of power •...

  • Page 523: Cvt Cooling Ducts

    7.CVT MXU 550i CVT Cooling Ducts SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Front Remove these components Component Topic Front rack Racks Seat Seat Front cover Front Cover Side covers Side Covers Fuel tank cover Fuel Tank Front mudguard fasteners Mudguards and Footrests...
  • Page 524 7.CVT MXU 550i To remove the upper front cooling duct remove the bolt with a 10 mm socket. Rear Remove these components Component Topic Rear rack Racks Seat Seat Right mudguard Mudguards and Footrests Side covers Side Covers Battery Battery Rear Fender Rear Fender Loosen the clamp with a #2 Phillips screwdriver.
  • Page 525 7.CVT MXU 550i Loosen the clamp and remove the lower cooling duct from the upper. Remove the two bolts to remove the upper cooling duct. Installation Front Install the upper front cooling duct into place. Insert the bolt and tighten it securely with a 10 mm socket.
  • Page 526 7.CVT MXU 550i Connect the lower front cooling to the upper duct and belt case. Install the clamps and tighten them securely with a #2 Phillips screwdriver. Install these components Component Topic Front fender Front Fender Front mudguard fasteners Mudguards and Footrests Fuel tank cover Fuel Tank Side covers...
  • Page 527 7.CVT MXU 550i Rear Fit the rear upper cooling duct into place and install the two bolts. Install the lower cooling duct to the upper. Tighten the clamps securely with a #2 Phillips screwdriver. Install these components Component Topic Rear fender Rear Fender Battery Battery...

  • Page 528: Belt Case Cover

    7.CVT MXU 550i Belt Case Cover MXU500i SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Drain Bolt There is a drain bolt on the bottom of the belt case. If this bolt is removed and any fluid comes out the CVT belt and pulleys should be inspected.
  • Page 529 7.CVT MXU 550i There are 10 belt case cover bolts. Loosen the belt case cover bolts with an 8 mm socket.
  • Page 530 7.CVT MXU 550i Remove the bolts and their rubber grommets. Utilize the pry points and remove the belt case cover. 7-10...
  • Page 531 7.CVT MXU 550i Remove the belt case cover rubber gasket. Remove the two belt case cover dowel pins. 7-11...
  • Page 532 7.CVT MXU 550i Inspection Inspect the drive belt for cracks or excessive wear. Measure the distance between the pulley faces at the top of the belt as indicated (A). Item Standard mm (in) Service Limit Drive belt width 34.1 (1.364) 30.8 (1.232) Replace the belt if it shows signs of damage or is out of specification.
  • Page 533 7.CVT MXU 550i Installation Install the two dowel pins into the belt case. Make sure the CVT belt case cover rubber gasket is in good condition. 7-13...
  • Page 534 7.CVT MXU 550i Install the CVT belt case cover rubber gasket. Install the belt case bolts with their gaskets. Install the wire clamp with the belt case bolt as shown. Tighten the bolts evenly in a crisscross pattern. 7-14...
  • Page 535 7.CVT MXU 550i Torque the belt case cover bolts to specification with an 8 mm socket. ITEM kgf-m ft-lb Belt case cover bolt Install the left footrest/mudguard. See the Mudguards and Footrests topic for more information. 7-15...

  • Page 536: Cvt Removal

    7.CVT MXU 550i CVT Removal SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Remove the belt case. See the Belt Case topic for more information. Note: Do not contaminate the CVT belt and pulley faces with grease or oil. Pulleys and Belt Hold the drive pulley with a drive pulley holder tool and loosen the nut with a 26 mm socket.
  • Page 537 7.CVT MXU 550i Slide the movable drive face of the drive pulley off of the drive pulley shaft. Hold the driven pulley with a Y-type holder and loosen the driven pulley nut with a 22 mm socket. Special Tool - Y-Type Holder: A120E00056 7-17...
  • Page 538 7.CVT MXU 550i Remove the driven pulley nut. Remove the driven pulley and CVT belt. 7-18...
  • Page 539 7.CVT MXU 550i Remove the washer from the driven pulley shaft. Remove the drive belt from the driven pulley. 7-19...
  • Page 540 7.CVT MXU 550i Inspect the drive belt for cracks or excessive wear. Slide off the fixed drive face of the drive pulley. 7-20...

  • Page 541: Drive Pulley Disassembly

    7.CVT MXU 550i Drive Pulley Disassembly Remove the boss from the movable drive face of the drive pulley. Lift the ramp plate out of the back of the movable drive pulley face. Remove the rubber damper pieces from the ramp. Replace the dampers if they are in poor condition.
  • Page 542 7.CVT MXU 550i There are eight weight rollers in the back of the right face of the drive pulley. Remove the rollers and check them for excessive or uneven wear. 7-22...
  • Page 543 7.CVT MXU 550i Measure the outside diameter of the rollers. Replace the weight rollers as needed. Item Standard mm (in) Service Limit Weight roller O.D. 29.9 - 30.1 (1.196 - 1.204) 29.5 (1.18) Remove the dust seals. 7-23...

  • Page 544: Driven Pulley Disassembly

    7.CVT MXU 550i Inspect the faces of the drive pulley. Clean away any grease from drive pulley components. Driven Pulley Disassembly A driven pulley spring compressor is needed to disassembly the driven pulley. Special Tool - Driven Pulley Spring Compressor: A120E00059 Fit the driven pulley onto the special tool.
  • Page 545 7.CVT MXU 550i Place the special tool in a vise. Note the wrench of the special tool. Turn in the nut to compress the spring. The nut must have enough room to come free. Loosen the nut with the wrench part of the special tool. 7-25...
  • Page 546 7.CVT MXU 550i Remove the special tool components and the nut. Remove the spring seat. 7-26...
  • Page 547 7.CVT MXU 550i Lift off the spring. Measure the free length of the spring. Replace the spring if it is out of specification. Item Standard mm (in) Service Limit Driven pulley spring 124.3 (4.972) 121.3 (4.852) 7-27...
  • Page 548 7.CVT MXU 550i Slide off the spring collar. Remove the four guide rollers with guide roller pins. 7-28...
  • Page 549 7.CVT MXU 550i Separate the fixed and movable faces of the driven pulley. Inspect the faces of the driven pulley. Clean away any grease from the faces where the belt rides. Remove the O-rings and seals from the movable face of the driven pulley. Clean the driven pulley components with a high flash point solvent and compressed air.

  • Page 550: Cvt Installation

    7.CVT MXU 550i CVT Installation SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Driven Pulley Install a new O-rings and dust seals into the movable face of the driven pulley. Drive in the new seals with a suitable driver with the same outside diameter as the seal. Coat the O-rings, seals, and inside of the movable face where it rides on the fixed face with grease.
  • Page 551 7.CVT MXU 550i Lubricate the guide pins and rollers with grease. Place the rollers on the pins and insert the pins into driven pulley. Make sure the movable drive face moves smoothly in and out on the fixed face. Install the spring collar. 7-31...
  • Page 552 7.CVT MXU 550i Install the spring. Install the spring seat. 7-32...
  • Page 553 7.CVT MXU 550i Place the nut over the spring seat. Fit the driven pulley onto the special tool. Fit the posts on the tool into the holes as shown. Special Tool - Driven Pulley Spring Compressor: A120E00059 7-33...
  • Page 554 7.CVT MXU 550i Place the special tool in a vice. Set the wrench part of the tool around the nut. Compress the spring with the special tool. Tighten the nut to specification with the special tool. ITEM kgf-m ft-lb Driven pulley spring nut 7-34...

  • Page 555: Drive Pulley

    7.CVT MXU 550i Drive Pulley Lubricate the lips of the new dust seals with a light coat grease. Drive in the new seals with a suitable driver with the same outside diameter as the seal. Insert the boss into the movable drive face. Apply a light coat of grease to the inside of the boss.
  • Page 556 7.CVT MXU 550i Install the rollers into the back of the movable drive face of the drive pulley. Position the rollers so that their thick sides are clockwise. Install the eight rollers. 7-36...
  • Page 557 7.CVT MXU 550i Fit the four rubber damper pieces onto the ramp. Fit the ramp into the back of the movable drive face of the drive pulley. Make sure the rubber dampers fit onto the ridges as shown. Pulleys and Belt Make sure the pulley faces are clean and grease free where they will contact the belt.
  • Page 558 7.CVT MXU 550i When the drive belt is installed make sure that the arrows are pointing towards the drive pulley when the arrow marks are on the top run of the belt. Install the washer onto the driven pulley shaft. 7-38...
  • Page 559 7.CVT MXU 550i Protect the threads on the driven pulley with a block. Use a commercial bearing puller to compress the driven pulley spring. Fit the belt into the driven pulley and remove the bearing puller and block. 7-39...
  • Page 560 7.CVT MXU 550i Install the driven pulley onto the driven pulley shaft. Lubricate the threads of the driven pulley nut with oil. Thread on the driven pulley nut. 7-40...
  • Page 561 7.CVT MXU 550i Hold the driven pulley with a Y-type holder and tighten the driven pulley nut to specification with a 22 mm socket. Special Tool - Y-Type Holder: A120E00056 ITEM kgf-m ft-lb Driven pulley nut Slide the movable drive face of the drive pulley onto the drive pulley shaft. Grasp the upper and lower runs of the belt together between the drive and driven pulleys to allow for extra 7-41...
  • Page 562 7.CVT MXU 550i slack in the belt as it sits on the drive pulley faces. Adjust the position of the belt so that when the drive pulley nut is tighten the belt will not be pinched. Caution: If the belt is sitting too low in the drive pulley it can be pinched when the nut is tightened.

  • Page 563: Clutch Removal

    7.CVT MXU 550i Clutch Removal MXU500i SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove the CVT belt case cover. See the Belt Case Cover topic for more information. Remove the CVT pulleys and belt. See the CVT Removal topic for more information.
  • Page 564 7.CVT MXU 550i Remove the CVT fan cover. Loosen the 9 clutch cover bolts a little bit at a time and in a crisscross pattern. 7-44...
  • Page 565 7.CVT MXU 550i Remove the clutch cover bolts. Remove the clutch cover assembly evenly. 7-45...
  • Page 566 7.CVT MXU 550i Remove the two dowel pins and the clutch cover gasket. Free the stake on the clutch nut with a chisel and a hammer. 7-46...
  • Page 567 7.CVT MXU 550i Hold the clutch with the Y-type holder and loosen the clutch nut with a commercially available 26 mm deep well socket. Special Tool - Y-Type Holder: A120E00056 Lock Nut Wrench: A120E00079 Remove the clutch nut. 7-47...
  • Page 568 7.CVT MXU 550i Slide off the outer clutch collar. Slide the clutch assembly off of the crankshaft. 7-48...
  • Page 569 7.CVT MXU 550i Slide off the inner clutch collar. Inspection Remove the clutch outer and drive pulley shaft from the clutch cover. 7-49...
  • Page 570 7.CVT MXU 550i To check the one-way clutch in the clutch outer temporarily install the clutch and set the clutch outer in place without the cover. When turning the clutch outer clockwise, the clutch outer should turn freely. If not, the one-way clutch assembly is faulty and should be replaced.
  • Page 571 7.CVT MXU 550i Remove the one-way clutch and replace it as needed. Install the clutch outer to the crankshaft with without the clutch and collars. When turning the clutch outer clockwise or counterclockwise, the clutch outer should turn smoothly. If not, the needle bearing or the clutch outer is damaged.
  • Page 572 7.CVT MXU 550i If the needle bearing is in poor condition remove the snap ring and replace the bearing. Press in a new bearing and secure it with a new snap ring. Make sure the snap ring is secure in its groove. Check the clutch linings for abnormal wear and damage.
  • Page 573 7.CVT MXU 550i Replace the clutch if the lining thickness is below 1 mm (0.04 in). Inspect the clutch bearing by turning it with a finger. Replace the bearing if it doesn't turn smoothly or it has excessive play. 7-53...
  • Page 574 7.CVT MXU 550i Inspect the clutch cover oil seal and replace it as needed. Inspect the large ball bearing in the clutch cover. Turn the bearing with a finger. Replace the bearing if it doesn't turn smoothly. Remove the seal cover to replace the bearing. 7-54...
  • Page 575 7.CVT MXU 550i Remove the four seal cover bolts with an 8 mm socket. Take off the seal cover and discard the gasket. Drive the bearing out from the outside of the clutch cover. Drive in the new bearing from the inside of the clutch cover.
  • Page 576 7.CVT MXU 550i Press a new seal into the seal cover. Use a suitable driver that is the same outside diameter as the seal. Apply a light coat lightweight lithium-soap based grease to the lips of the oil seal. For clutch assembly and installation see the Clutch Installation topic for more information.

  • Page 577: Clutch Installation

    7.CVT MXU 550i Clutch Installation SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Fit the seal cover to the clutch cover with a new gasket. Install the four seal cover bolts and tighten them securely with an 8 mm socket. 7-57...
  • Page 578 7.CVT MXU 550i Install the one-way clutch into the clutch outer if it was removed. Lubricate the one-way clutch bearings with molybdenum disulfide grease. Apply a light coat lightweight lithium-soap based grease to the lips of the oil seal. Lubricate the clutch bearings with fresh engine oil.
  • Page 579 7.CVT MXU 550i Lubricate the inner clutch collar with fresh engine oil and slide it onto the crankshaft as shown. Slide the clutch onto the crankshaft. Be sure to align the splines. 7-59...
  • Page 580 7.CVT MXU 550i Slide the outer clutch collar onto the crankshaft. Thread on a new clutch lock nut. 7-60...
  • Page 581 7.CVT MXU 550i Hold the clutch with the Y-type holder and torque the clutch nut to specification with a deep well commercially available 26 mm socket. Special Tool - Y-Type Holder: A120E00056 Lock Nut Wrench: A120E00079 ITEM kgf-m ft-lb Clutch nut 100.8 7-61...
  • Page 582 7.CVT MXU 550i Stake the clutch nut at the groove on the crankshaft with a chisel and a hammer. Be careful to avoid damaging the threads. Install the two dowel pins and a new clutch cover gasket. Guide the clutch cover assembly into place evenly. 7-62...
  • Page 583 7.CVT MXU 550i Insert the 9 clutch cover bolts. Tighten the clutch cover bolts a little bit at a time in a crisscross pattern. Torque the bolts to specification with an 8 mm socket. ITEM kgf-m ft-lb Clutch cover bolt 7-63...
  • Page 584 7.CVT MXU 550i Install the CVT fan cover. Install the five CVT fan cover bolts and tighten them securely with an 8 mm socket. Install the CVT pulleys and belt. See the CVT Installation topic for more information. 7-64...

  • Page 585: Final Drive

    8.Final Drive MXU 550i Final Drive This chapter covers the location and servicing of the final drive components for the KYMCO MXU 550i models. Drive Shafts ......................8-3 Differential Removal and Installation ..............8-16 Differential Disassembly ..................8-23 Differential Assembly .................... 8-52 Rear Final Drive Gear .....................

  • Page 586: Troubleshooting

    8.Final Drive MXU 550i TROUBLESHOOTING 1. A pronounced hesitation movement during acceleration, deceleration, or sustained speed. (This must not be confused with engine surging or transmission characteristics.) 2. A “rolling rumble” noticeable at low speed; a high-pitched whine from front drive component or area.

  • Page 587: Drive Shafts

    8.Final Drive MXU 550i Drive Shafts SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Boot Inspection Inspect the drive shaft protective boots for wear and damage. Replace the boots if they are damaged or punctured. Removal Remove these components Component Topic Wheels and hubs...
  • Page 588 8.Final Drive MXU 550i Remove the drive shaft horizontally. Repeat the procedure on the other side. Remove the circlips from the inside ends of the drive shafts. Inspection Check the axle for bends or damage. Check the boots and boot bands for any damage or excessive wear.
  • Page 589 8.Final Drive MXU 550i Push and pull on the axle shaft and wheel spindle to check the play in the axle. Disassembly Carefully remove the boot bands and discard.
  • Page 590 8.Final Drive MXU 550i Note: To remove the boot on the wheel side remove the boot on the case side first. Pull the boot off the outer race.
  • Page 591 8.Final Drive MXU 550i Remove the stopper ring from the outer race with a flat head screwdriver. Remove the outer race. Wipe off any grease and remove the snap ring with a pair of snap ring pliers. Carefully drive the shaft out of the cage.
  • Page 592 8.Final Drive MXU 550i Remove the cage and replace if needed. Remove the stopper ring and boot. Clean the boot with a clean shop rag. Inspect the boots and replace if they are damaged. Remove and discard all the boot bands.
  • Page 593 8.Final Drive MXU 550i Inspect the circlip and snap ring and outer race for wear or damage. If any damage is found, replace part(s) with new ones. Inspect the cage and inner surface of case side joint for pitting, wear or damage. If any damages are found, replace them with new ones.
  • Page 594 8.Final Drive MXU 550i Assembly Install a new small boot band onto the shaft groove end. Note: The end of the boot band should face away from the rotation of the drive shaft. 8-10...
  • Page 595 8.Final Drive MXU 550i Fit a boot on the drive shaft end, fitting the small diameter side of the boot to the shaft groove. Fix its end with the small boot band. Install the cage on the shaft with the large diameter side facing the shaft end. 8-11...
  • Page 596 8.Final Drive MXU 550i Install the snap ring into the groove with a pair of snap ring pliers. Apply molybdenum disulfide grease to the entire surface of the cage and the inside of the case side joint/wheel side joint. Location Wheel Side Joint Case Side Joint Quantity...
  • Page 597 8.Final Drive MXU 550i Insert the cage into the case side joint (outer race). Install the stopper ring in the groove of the case side. Note: Locate the opening of the circlip so that the opening is not lined up with any ball in the cage.
  • Page 598 8.Final Drive MXU 550i After fitting the boot on the case side joint, insert a screw driver into the boot on the case side joint and allow air to enter the boot so that the air pressure in the boot becomes the same as the atmospheric pressure.

  • Page 599: Installation

    8.Final Drive MXU 550i Note: The end of the boot band should face away from the rotation of the drive shaft. Note: The dust boots should be fastened with the boot bands at the grooves in the drive shaft. Installation Insert a new stopper ring into the groove in the shaft splines.

  • Page 600: Differential Removal And Installation

    8.Final Drive MXU 550i Differential Removal and Installation SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove these components Component Topic Front rack Racks Side covers Side Covers Fuel tank Fuel Tank Mudguards Mudguards and Footrests Front fender Front Fender Front wheels...
  • Page 601 8.Final Drive MXU 550i Inspect the breather hose and case for damage. Squeeze and slide back the clamp to remove the breather hose and case. Hold the differential mounting bolts and loosen the nuts. Remove the two differential mounting nuts and bolts. 8-17...
  • Page 602 8.Final Drive MXU 550i Disconnect the front propeller shaft from the differential. Inspect the splines. Take care to not lose the spring. Check that the U-joints move smoothly. Replace as needed. 8-18...
  • Page 603 8.Final Drive MXU 550i Remove the differential from the frame. To disassemble the front differential see the Differential Disassembly topic for more information. Installation Install the differential onto the vehicle. 8-19...
  • Page 604 8.Final Drive MXU 550i Lubricate the splines of the propeller shaft with water-proof grease. Make sure the spring fits between the propeller shaft and the differential. Install the propeller shaft between the engine and the differential. Fit the rubber boot into place so that it rides on the differential yoke and the propeller shaft.
  • Page 605 8.Final Drive MXU 550i Install the two differential nuts and bolts. Hold the bolts and tighten the nuts to specification. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Rear gear case and frame 5.3 (53, 38) Install the breather hose and case. Secure the hose with the clamp. 8-21...
  • Page 606 8.Final Drive MXU 550i Plug in the 2WD/4WD shifting motor connector. Secure the wires to the frame with the wire band. Install these components Drive shafts Drive Shafts Front A-arms (front) A-arms Fill the differential oil Final Drive Oil Front Wheels Wheels Front fender Front Fender...

  • Page 607: Differential Disassembly

    8.Final Drive MXU 550i Differential Disassembly SAFETY FIRST: Protective gloves and eyewear are recommended at this point. 2WD/4WD Shifting Motor Assembly To test the 2WD/4WD shifting motor assembly see the Switches topic. The 2WD/4WD shifting motor assembly is mounted to the front differential with three bolts. Remove the 2WD/4WD shifting motor assembly bolts.
  • Page 608 8.Final Drive MXU 550i Remove the cap. The 2WD/4WD shifting rod is held in place by a small circlip. 8-24...
  • Page 609 8.Final Drive MXU 550i Carefully spread the circlip and remove it. Remove the spacer. 8-25...

  • Page 610: Pinion Housing

    8.Final Drive MXU 550i Slide the 2WD/4WD shifting motor assembly back and free it from the actuator fork rod. Remove the 2WD/4WD shifting motor assembly. Pinion Housing 8-26...
  • Page 611 8.Final Drive MXU 550i Remove the three pinion housing bolts with a 12 mm socket. Remove the bracket. 8-27...
  • Page 612 8.Final Drive MXU 550i Remove the pinion housing. Remove the dowel pin. Remove the gasket. 8-28...
  • Page 613 8.Final Drive MXU 550i To remove the 2WD/4WD shifting and locking components remove the plug with a large flat blade screwdriver. Inspect the O-ring and replace it as needed. The differential locking shaft is held in place by a small circlip. Carefully spread the circlip and remove it.
  • Page 614 8.Final Drive MXU 550i Slide the 2WD/4WD shifting and locking components out of the pinion housing. Remove the drive coupler from the fork. Inspect the drive coupler for wear and damage. Inspect the 2WD/4WD shifting and locking rod components for wear and damage. 8-30...
  • Page 615 8.Final Drive MXU 550i To disassemble the individual components of the 2WD/4WD shifting and locking assembly remove the two snap rings with snap ring pliers. To remove the input shaft remove the snap ring with snap ring pliers. 8-31...

  • Page 616: Bearing Replacement

    8.Final Drive MXU 550i Remove the input shaft from the pinion housing. Check the input shaft splines for wear and damage. Inspect the input shaft seals and replace as needed. Bearing replacement Inspect the pinion housing seal and bearing. 8-32...
  • Page 617 8.Final Drive MXU 550i If the bearing or seal needs to be replaced remove the seal with a seal pick. Remove the snap ring with snap ring pliers. 8-33...
  • Page 618 8.Final Drive MXU 550i Drive the bearing out from the inside of the housing. Drive in the new bearings with a suitable bearing driver that has the same outside diameter of the bearing. The manufactures markings on the bearing must face out. Special Tool - Bearing Driver: A120E00014 8-34...
  • Page 619 8.Final Drive MXU 550i Secure the new bearing by installing a new snap ring into the groove with snap ring pliers. Apply waterproof grease to the lips of the new seal. Press in the seal with a suitable driver that has the same outside diameter as the seal. Differential Loosen the 10 differential cover bolts evenly with a 12 mm socket.
  • Page 620 8.Final Drive MXU 550i Remove the differential cover bolts. Utilize the pry points and separate the cover from the differential case. 8-36...
  • Page 621 8.Final Drive MXU 550i Remove the differential cover from the case. Remove the gasket. Remove the dowel pins. 8-37...
  • Page 622 8.Final Drive MXU 550i Inspect the differential cover seals. Replace them as needed. Apply waterproof grease to the lips of the new seals. Press in the seal with a suitable driver that has the same outside diameter as the seal. Remove the differential locking fork and collar.
  • Page 623 8.Final Drive MXU 550i Inspect the differential locking fork and collar for wear and damage. Use a suitable driver and tap out the ring gear assembly. 8-39...
  • Page 624 8.Final Drive MXU 550i Remove the ring gear assembly from the differential case. Lift off the bearing plate. 8-40...
  • Page 625 8.Final Drive MXU 550i Inspect the bearing plate bearing and replace it as needed. Drive in the new bearing with a suitable bearing driver that has the same outside diameter of the bearing. The manufactures markings on the bearing must face out. Remove the shims from each side of the ring gear.
  • Page 626 8.Final Drive MXU 550i Inspect the ring gear for wear and damage. Inspect the differential case bearing and seal. Remove the seal with a seal pick if needed. 8-42...
  • Page 627 8.Final Drive MXU 550i Drive the bearing out from the outside if needed. Drive in the new bearing with a suitable bearing driver that has the same outside diameter of the bearing. The manufactures markings on the bearing must face out. 8-43...

  • Page 628: Pinion Gear

    8.Final Drive MXU 550i Pinion Gear Unstake the pinion gear locknut with a suitable punch or a drill. Be very careful to avoid damaging the differential case. Place the differential case in a vice. Use soft jaws or other suitable method to prevent damage to the differential case and its mating surface.
  • Page 629 8.Final Drive MXU 550i Special Tool - Bearing Driver: A120F00025 Remove the pinion gear nut. Drive out the pinion gear shaft with a suitable punt or drift with a hammer. 8-45...
  • Page 630 8.Final Drive MXU 550i Remove the pinion gear and ball bearing from the differential case. Inspect the pinion gear, shaft, and ball bearing. Replace the parts as needed. 8-46...
  • Page 631 8.Final Drive MXU 550i Pinion Gear Shaft Bearings Use a commercially available bearing puller to free the ball bearing from the pinion gear shaft. Use a press and a split bearing puller if available. 8-47...
  • Page 632 8.Final Drive MXU 550i Remove the ball bearing, and spacer from the pinion gear shaft. Use a press to install the new bearing and spacer onto the pinion gear shaft. 8-48...
  • Page 633 8.Final Drive MXU 550i Inspect the pinion gear shaft needle bearing in the differential case. Remove the pinion gear needle bearing with a suitable bearing puller. 8-49...
  • Page 634 8.Final Drive MXU 550i Drive in a new pinion gear needle bearing with a suitable bearing driver that is the same outside diameter as the bearing. Backlash Inspection and Shim Adjustment Temporarily assemble the differential with the shims. Hold the pinion gear so that it doesn't move. Place a horizontal type dial gauge through the filler hole and against the ring gear of the differential.
  • Page 635 8.Final Drive MXU 550i If the right shim is changed the left shim/s needs to change to compensate. Gear Tooth Contact After the proper shims have been selected the gear tooth contact must be checked. Remove the differential and pinion gear. Clean the differential ring gear and pinion gear. Apply machinists dye to several teeth of the pinion gear.

  • Page 636: Differential Assembly

    8.Final Drive MXU 550i Differential Assembly SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Clean the final drive gear case components with a high flash point solvent and compressed air. NOTE: Always wear safety glasses when using compressed air and never point it directly at yourself or anyone else.
  • Page 637 8.Final Drive MXU 550i Install a new pinion gear locknut. Place the differential case in a vice. Use soft jaws or other suitable method to prevent damage to the differential case and its mating surface. Tighten the pinion gear nut to specification with the special locknut wrench.
  • Page 638 8.Final Drive MXU 550i Stake the pinion gear locknut with a suitable punch and hammer. Be very careful to avoid damaging the differential case. Differential Select the proper shims as covered in the Differential Disassembly topic. Install the correct shims onto each side of the ring gear. 8-54...
  • Page 639 8.Final Drive MXU 550i Fit the bearing plate into place as shown. Fit the ring gear assembly and bearing plate into the differential case. 8-55...
  • Page 640 8.Final Drive MXU 550i Install the differential locking fork and collar. Install the dowel pins and a new gasket. 8-56...
  • Page 641 8.Final Drive MXU 550i Fit the differential cover into place. The pin on the bearing plate must fit into the differential cover. The locking fork projection must fit into the space in the cover. Apply a light coat of Threebond 1215 or other equivalent sealant to the threads of the differential cover bolts.
  • Page 642 8.Final Drive MXU 550i Tighten the differential cover bolts evenly and securely with a 12 mm socket. ITEM kgf-m ft-lb Front drive (differential) case bolt 16.5 Pinion Housing Install the input shaft into the bearing. 8-58...
  • Page 643 8.Final Drive MXU 550i Install the snap ring into the groove with snap ring pliers. Lubricate the actuator fork and drive coupler with fresh differential oil. Fit the drive coupler into the fork as shown. Slide the 2WD/4WD shifting and locking components into the pinion housing. 8-59...
  • Page 644 8.Final Drive MXU 550i Install the spring, spring seat and circlip onto the locking shaft. Gently spread the circlip and slide it into place in the groove on the shaft. 8-60...
  • Page 645 8.Final Drive MXU 550i Install the plug. Make sure the O-ring is in good condition. Tighten the plug securely with a large flat blade screwdriver. Torque Item Q'ty Thread dia. (mm) Kgf-m (N-m, ft-lb) Shifting fork shaft plug 1.5 (15, 11) Install a new pinion housing gasket and dowel pin.
  • Page 646 8.Final Drive MXU 550i Apply a light coat of Threebond 1215 or other equivalent sealant to the threads of the pinion housing bolts. Install the bracket and the three pinion housing bolts. 8-62...
  • Page 647 8.Final Drive MXU 550i Tighten the pinion housing bolts securely with a 12 mm socket. 2WD/4WD Shifting Motor Assembly Lubricate the shifting motor assembly O-ring with grease. 8-63...
  • Page 648 8.Final Drive MXU 550i Install the 2WD/4WD shifting motor assembly. Guide the rod into the shifting motor assembly. Apply Threebond sealant to the threads of the 2WD/4WD shifting motor assembly mounting bolts. The install the three 2WD/4WD shifting motor assembly mounting bolts. 8-64...
  • Page 649 8.Final Drive MXU 550i Tighten the 2WD/4WD shifting motor assembly bolts to specification. Torque Thread dia. Item Q'ty Kgf-m (N-m, Remarks (mm) ft-lb) 2WD/4WD shift motor Apply threebond: 2.3 (23, 16.5) mounting bolt 1215 2WD/4WD shift motor 1.2 (12, 8.5) mounting bolt Install the spacer onto the 2WD/4WD shifting rod.
  • Page 650 8.Final Drive MXU 550i Carefully spread the circlip and install it into the groove in the 2WD/4WD shifting rod. Apply a light coat of silicone sealant to the outside of the plug and install the plug. Install the differential. See the Differential Removal and Installation topic for more information.

  • Page 651: Rear Final Drive Gear

    8.Final Drive MXU 550i Rear Final Drive Gear SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove these components Rear wheels Wheels and Wheel Hubs Rear knuckles and suspension arms Rear Suspension Arms Drive shafts Drive Shafts Drain the rear gear oil Final Drive Oil Remove the rear brake calipers...

  • Page 652: Installation

    8.Final Drive MXU 550i Remove the rear final gear case from the frame. To remove the brake disc see the Brake Discs topic. To disassemble the rear final drive unit see the Final Drive Gear Disassembly topic. Installation Apply grease to the splines of the propeller shaft. Make sure the propeller shaft spring is in place as shown.
  • Page 653 8.Final Drive MXU 550i Install the rear final drive unit into the frame. Install the rear propeller shaft. Install the two gear case mounting bolts and nuts. Hold the bolts with a 14 mm wrench and tighten the nuts to specification with a 17 mm socket. Item Kgf-m lbf-ft...
  • Page 654 8.Final Drive MXU 550i Install these components Rear brake calipers Rear Brake Calipers Drive shafts Drive Shafts Rear knuckles and suspension arms Rear Suspension Arms Fill the rear gear oil Final Drive Oil Rear wheels Wheels and Wheel Hubs 8-70...

  • Page 655: Final Drive Gear Disassembly

    8.Final Drive MXU 550i Final Drive Gear Disassembly SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Remove the rear final drive. See the Rear Final Drive Gear topic for more information. Rear Brake Disc and Holder 8-71...
  • Page 656 8.Final Drive MXU 550i Remove the five rear brake disc bolts with a 6 mm Allen socket. Remove the rear brake disc from the brake disc holder. 8-72...
  • Page 657 8.Final Drive MXU 550i Remove the spring from the brake disc holder. Loosen the rear brake disc holder bolt with a 14 mm socket. Remove the rear brake disc holder from the pinion shaft. 8-73...
  • Page 658 8.Final Drive MXU 550i Loosen the four rear brake caliper holder bolts with a 12 mm socket. Remove the four rear brake caliper holder bolts. Note there are two different sizes for the rear brake caliper holder bolts. 8-74...
  • Page 659 8.Final Drive MXU 550i Remove the rear brake caliper holder. Remove the two dowel pins. Backlash Inspection and Shim Adjustment Temporarily assemble the rear final gear with the shims. Hold the pinion gear so that it doesn't move. Place a horizontal type dial gauge through the filler hole and against the ring gear of the differential.
  • Page 660 8.Final Drive MXU 550i Backlash Right Shim adjustment Under 0.05 mm (0.0020 in) increase shim thickness 0.05 - 0.25 mm (0.002 - 0.010 in) Correct Over 0.25 mm (0.010 in) Decrease shim thickness If the right shim is changed, the left shim/s needs to change to compensate. Gear Tooth Contact After the proper shims have been selected the gear tooth contact must be checked.
  • Page 661 8.Final Drive MXU 550i The dye should show the contact area of the gear teeth is centered on the teeth. If the contact is too high or low on the teeth the pinion gear shaft shims must be changed so that the tooth contact is correct while maintaining the correct backlash.
  • Page 662 8.Final Drive MXU 550i The rear final drive cover has eight bolts. There are two large bolts (arrows) and six small bolts (circles). Loosen the small bolts with a 12 mm socket. Remove the two large bolts with a 14 mm socket. 8-78...
  • Page 663 8.Final Drive MXU 550i Utilize the pry point and remove the rear final gear case cover. Ring and Pinion Gears Remove the ring gear. Remove the shims from each side of the ring gear. Keep track of the location of the shims so that they can be returned to their original positions.
  • Page 664 8.Final Drive MXU 550i Inspect the ring and pinion gears for wear and damage. If the pinion gear shaft needs to be removed the oil seal must be removed first. Remove the pinion shaft oil seal with a seal pick. The pinion gear shaft has a locknut that requires a special tool to remove.
  • Page 665 8.Final Drive MXU 550i Place the final gear case in a vice. Use soft jaws or other suitable method to prevent damage to the case and its mating surface. Secure the case in a soft jawed vise and remove the locknut with the special wrench. Special Tool - Pinion Gear Shaft Puller: A120F00020 To remove the pinion shaft a special tool set is needed.
  • Page 666 8.Final Drive MXU 550i Lubricate the puller threads with grease. Thread the puller part of the tool into the pinion gear shaft. 8-82...
  • Page 667 8.Final Drive MXU 550i Install the puller plate onto the final gear case. Thread the shaft onto the puller. 8-83...
  • Page 668 8.Final Drive MXU 550i Install the rest of the tool. Hold the shaft still and turn the nut with a large wrench to pull the shaft up. 8-84...
  • Page 669 8.Final Drive MXU 550i Remove the pinion gear shaft from the case. Inspect the pinion shaft, gear, and bearing for wear and damage. The bearing must be removed to access the shim. Bearing Replacement Pinion Bearing 8-85...
  • Page 670 8.Final Drive MXU 550i Use a commercially available bearing puller or press to free the ball bearing from the pinion gear shaft. Remove the shim. Be sure to have the appropriate shim for installation. 8-86...
  • Page 671 8.Final Drive MXU 550i Install the shim and press the new bearing onto the shaft. Final Gear Case Pinion Gear Needle Bearing Inspect the pinion gear shaft needle bearing in the case. 8-87...
  • Page 672 8.Final Drive MXU 550i Remove the needle bearing snap ring with snap ring pliers. Remove the pinion gear needle bearing with a suitable bearing puller. 8-88...
  • Page 673 8.Final Drive MXU 550i Drive in a new pinion gear needle bearing with a suitable bearing driver that is the same outside diameter as the bearing. Lubricate the new needle bearing with fresh final drive oil. 8-89...
  • Page 674 8.Final Drive MXU 550i Install a new snap ring into the groove with snap ring pliers. Cover Ring Gear Bearing Inspect the final drive gear cover bearing and seal. Remove the oil seal with a seal pick if needed. 8-90...
  • Page 675 8.Final Drive MXU 550i Drive the final drive gear cover bearing out from the outside of the final drive gear cover. Drive the new bearing into the final drive gear cover with a suitable driver that is the same outside diameter as the bear. The markings on the bearing must face out. Special Tool - Bearing Driver: A120E00014 8-91...
  • Page 676 8.Final Drive MXU 550i Apply waterproof grease to the lips of the new seal. Press in the seal with a suitable driver that has the same outside diameter as the seal. Final Gear Case Ring Gear Bearing Inspect the final drive gear case bearing and seal. 8-92...
  • Page 677 8.Final Drive MXU 550i Remove the oil seal with a seal pick if needed. Remove the circlip with snap ring pliers. 8-93...
  • Page 678 8.Final Drive MXU 550i Drive the drive gear case bearing out from the inside. Drive the new bearing into the final drive gear cover with a suitable driver that is the same outside diameter as the bearing. The markings on the bearing must face out. Install a new snap ring into the groove with snap ring pliers.
  • Page 679 8.Final Drive MXU 550i Apply waterproof grease to the lips of the new seal. Press in the seal with a suitable driver that has the same outside diameter as the seal. To assemble the final drive gear case see the Final Drive Gear Assembly topic.

  • Page 680: Final Drive Gear Assembly

    8.Final Drive MXU 550i Final Drive Gear Assembly SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Pinion Gear Shaft Install the pinion shaft assembly into the final gear case. Tap it in with a rubber mallet to seat the bearing.
  • Page 681 8.Final Drive MXU 550i Apply a non-permanent thread locking agent (Blue Loctite) to the threads of the pinion gear shaft locknut. Do not contaminate the bearing with the locking agent. Thread the locknut into the gear case. Secure the case in a soft jawed vise and torque the locknut to specification with the special wrench.
  • Page 682 8.Final Drive MXU 550i Apply waterproof grease to the lips of the new pinion gear shaft oil seal. Press in a new pinion gear shaft oil seal. Use a suitable driver that is the same outside diameter as the seal. Ring Gear 8-98...
  • Page 683 8.Final Drive MXU 550i Install the ring gear with the correct shims to each side. Final Gear Case Cover Apply a silicone sealant to the mating surface of the final gear case cover. Do not allow the sealant to contaminate the bearings or gears. 8-99...
  • Page 684 8.Final Drive MXU 550i Fit the final gear case cover into place. Apply a light coat of Threebond 1215 or other equivalent sealant to the threads of the cover bolts. Install the eight rear final drive cover bolts. There are two large bolts (arrows) and six small bolts (circles).
  • Page 685 8.Final Drive MXU 550i Tighten the bolts to specification evenly. Use a 12 mm socket for the smaller bolts and a 14 mm socket for the two larger bolts. ITEM kgf-m ft-lb Rear final gear case bolt (M10) Rear final gear case bolt (M8) Install the breather vent tube to the rear final drive gear case and secure it with the clamp.
  • Page 686 8.Final Drive MXU 550i Install the rear brake caliper holder. Install the four rear brake caliper holder bolts to their original positions with washers. 8-102...
  • Page 687 8.Final Drive MXU 550i Tighten the rear brake caliper holder bolts securely with a 12 mm socket. Insert the rear brake disc holder into place on the pinion gear shaft. 8-103...
  • Page 688 8.Final Drive MXU 550i Apply a non-permanent thread locking agent (Blue Loctite) to the threads of the rear brake disc holder bolt. Tighten the rear brake disc holder bolt to specification with a 14 mm socket. Coat the splines inside the rear brake disc holder with waterproof grease. Insert the spring into the rear brake disc holder.
  • Page 689 8.Final Drive MXU 550i Fit the rear brake disc into place. Do not contaminate it with oil or grease. 8-105...
  • Page 690 8.Final Drive MXU 550i Install the five rear brake disc mounting bolts and tighten them to specification with a 6 mm Allen socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Rear brake disc and rear hub 3.5 (35, 25) Install the rear final drive gear case.

  • Page 691: Brake System

    9..Brake System MXU 550i Brake System This chapter covers the location and servicing of the front brake components for the KYMCO MXU 550i models. Brake Discs ......................9-3 Brake Pedal and Master Cylinder ................9-8 Front Brake Calipers ....................9-26 Rear Brake Calipers ....................

  • Page 692: Poor Brake Performance

    9..Brake System MXU 550i Poor brake performance Air in brake system • Deteriorated brake fluid • Contaminated brake pads and brake disk • Worn brake pads • Worn brake master cylinder piston oil seal • Clogged brake fluid line • Deformed brake disk •...

  • Page 693: Brake Discs

    9..Brake System MXU 550i Brake Discs SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Inspection Remove the wheels. See the Wheels and Wheel Hubs topic for more information. Check the brake discs for damage or excessive wear. Using a dial gauge and stand measure the disc brake runout.
  • Page 694 9..Brake System MXU 550i Measure the brake disc thickness with a micrometer. Replace the rotor if it is below the service limit. Item Standard mm (in) Service Limit Brake disk thickness FR: 4.0 (0.156) RR: 5.0 (0.195) FR: 3 (0.12) RR: 4 (0.156) Removal Front To remove the brake disc take out the four disc brake bolts with a Torx socket wrench.
  • Page 695 9..Brake System MXU 550i Remove the five rear brake disc bolts with a 6 mm Allen socket. Remove the rear brake disc from the brake disc holder.

  • Page 696: Installation

    9..Brake System MXU 550i Installation Front Install the disc brake onto the wheel hub. Tighten the four bolts to specification with a Torx socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Front brake disc and front hub 2.0 (20, 14) Install the front wheels.
  • Page 697 9..Brake System MXU 550i Fit the rear brake disc into place. Do not contaminate it with oil or grease. Install the five rear brake disc mounting bolts and tighten them to specification with a 6 mm Allen socket. Torque Item Thread dia.

  • Page 698: Brake Pedal And Master Cylinder

    9..Brake System MXU 550i Brake Pedal and Master Cylinder SAFETY FIRST: Protective gloves and eyewear are recommended at this point. NOTE: Brake fluid is a corrosive chemical and can damage paints and some plastics. Avoid contact with skin. There are two rear brake calipers. The caliper that mounts to the top of the final drive gear is connected to the pedal activated master cylinder.
  • Page 699 9..Brake System MXU 550i Drain the brake fluid from the brake pedal master cylinder system if the master cylinder is to be disconnected from the brake hose. See the Brake Fluid topic for more information. Remove the master cylinder reservoir mounting bolt with a #3 Phillips screwdriver.
  • Page 700 9..Brake System MXU 550i Remove the two brake pedal pivot mounting bolts. Loosen the brake hose banjo bolt with a 12 mm socket. Remove the banjo bolt and the two sealing washers. Remove the two master cylinder mounting bracket nuts with a 12 mm socket.
  • Page 701 9..Brake System MXU 550i Remove the pedal and master cylinder assembly from the frame. Disassembly 9-11...
  • Page 702 9..Brake System MXU 550i Remove the two cotter pins, washers, and joints to remove the brake rod. Remove the master cylinder rod cotter pin, washer, and pivot pin. Separate the master cylinder rod from the brake pedal. To remove the pedal from the bracket take out the cotter pin and remove the washer. Slide the pedal off of its pivot.
  • Page 703 9..Brake System MXU 550i To remove the reservoir hose slide up the clamp and free the hose form the master cylinder. To free the master cylinder from the bracket remove the two mounting bolts with a 10 mm socket. Use a spring puller to remove the pedal return spring and rear brake light switch spring. 9-13...
  • Page 704 9..Brake System MXU 550i To remove the master cylinder lever hold the bolt and loosen the nut. Remove the nut and bolt. Remove the lever from the master cylinder. 9-14...
  • Page 705 9..Brake System MXU 550i Take care to keep track of the washers that sit on each side of the lever. Remove the reservoir pipe snap ring with snap ring pliers. Lift out the reservoir pipe. Inspect the O-ring and replace it as needed. Remove the rubber cover from the master cylinder piston.
  • Page 706 9..Brake System MXU 550i Remove the snap ring using a pair of internal snap ring pliers. Use a suitable tool to hold back the piston as it can spring out. Remove the piston and spring from the master cylinder. 9-16...
  • Page 707 9..Brake System MXU 550i Inspect the piston, seals, and master cylinder bore for wear and damage. Replace the master cylinder an assembly if the components are damaged. Assembly Clean the master cylinder components with fresh brake fluid (DOT-4). Lubricate the piston and seals with fresh brake fluid. Insert the spring and piston into the master cylinder.
  • Page 708 9..Brake System MXU 550i Push in the piston and install the snap ring into its groove with snap ring pliers. Install the rubber cover over the piston. 9-18...
  • Page 709 9..Brake System MXU 550i Install the reservoir pipe with an O-ring in good condition. Install the snap ring into its groove with snap ring pliers. Place washers on each side of the master cylinder lever. 9-19...
  • Page 710 9..Brake System MXU 550i Install the lever into the master cylinder as shown. Apply a light coat of waterproof grease to the pivot bolt. Install the pivot bolt and nut and tighten them securely. 9-20...
  • Page 711 9..Brake System MXU 550i Install the bracket to the master cylinder and tighten the two bolts securely. Use a spring puller to install the pedal return spring and rear brake light switch spring as shown. Connect the reservoir hose to the pipe and secure it with the clamp. 9-21...
  • Page 712 9..Brake System MXU 550i Apply a light coat of waterproof grease to the pedal pivot. Fit the pedal onto the pivot. Install the washer and a new cotter pin. Bend the pin as shown to secure the pedal and washer. 9-22...

  • Page 713: Installation

    9..Brake System MXU 550i Connect the brake rod to the pedal and lever. Install the joints, washers, and new cotter pins. Bend the cotter pins to secure the rod. Installation Fit the master cylinder and pedal into place on the right side of the frame. Install the two master cylinder mounting bracket nuts with a 12 mm socket and tighten them securely.
  • Page 714 9..Brake System MXU 550i Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Brake hose oil bolt 3.5 (35, 25) Install the two brake pedal pivot mounting bolts and tighten them securely. Fir the reservoir into place and install the mounting bolt. Tighten the bolt securely with a #3 Phillips screwdriver.
  • Page 715 9..Brake System MXU 550i Plug in the rear brake light switch connector. Fill the rear brake system with brake fluid and bleed out the air. See the Brake Fluid topic for more information. Adjust the rear brake pedal and brake light switch. See the Brake Fluid topic for more information.

  • Page 716: Front Brake Calipers

    9..Brake System MXU 550i Front Brake Calipers SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Warning: Brake fluid is very caustic and can damage paint, chrome and plastic. Wipe up any spills immediately. There are three brake calipers, two for the front, and one with the left rear wheel hub. Removal Remove the front wheels or left rear wheel as needed.

  • Page 717: Brake Pad Replacement

    9..Brake System MXU 550i Remove the brake caliper from the knuckle and disc. Note: Do not use the front brake while the caliper and brake pads are not installed on the vehicle. Brake Pad Replacement Push the pads and bracket in towards the caliper piston. Remove the brake pads. 9-27...
  • Page 718 9..Brake System MXU 550i Discard the brake pads if the linings are below 1 mm or 0.039 in thick. Install the brake pads. See the Installation section for more information. Disassembly Loosen the brake hose banjo bolt with a 12 mm socket. Remove the banjo bolt and sealing washers.
  • Page 719 9..Brake System MXU 550i Remove the caliper bracket. Inspect the caliper bracket O-rings and replace them as needed. NOTE: Always wear safety glasses when using compressed air and never point it directly at yourself or anyone else. Remove the pin boots from the caliper. 9-29...
  • Page 720 9..Brake System MXU 550i Place a thick rag over caliper piston and use compressed air to move the piston out. Do not place your fingers over the caliper piston while removing it as serious injury could result. Remove the caliper piston by hand. 9-30...
  • Page 721 9..Brake System MXU 550i Remove the dust seal from the caliper bore and discard. Use a mechanics pick to remove the piston fluid seal from the caliper bore and discard. 9-31...
  • Page 722 9..Brake System MXU 550i Inspection Check the brake caliper bore for any scratches, damage or excessive wear. Clean the brake caliper bore with DOT 4 brake fluid. Do not dry off with a rag. Check the piston for any scratches, damage or excessive wear. Clean the piston with DOT 4 brake fluid.
  • Page 723 9..Brake System MXU 550i Assembly Coat the new seals, piston, and piston bore with DOT 4 brake fluid. Install a new piston fluid seal into the inner groove. Install a new dust seal into the outer groove in the caliper bore. Install the piston into the caliper bore closed end first. Push the piston all the way in.
  • Page 724 9..Brake System MXU 550i Install the pin boots into the caliper. Apply silicone grease to the caliper bracket pins. Install the caliper bracket. 9-34...
  • Page 725 9..Brake System MXU 550i Installation Install the brake pads. Fit the brake caliper into place. Guide the brake disc between the pads. 9-35...
  • Page 726 9..Brake System MXU 550i Install the two brake caliper mounting bolts and tighten them to specification. TORQUE ITEM THREAD SIZE AND TYPE kgf-m Nm ft-lb CALIPER AND FR/RR KNUCKLE M8 X 1.25 2 4-3.2 24-32 20 Connect the brake hose to the caliper if it was removed. Use a new sealing washer on each side of the hose fitting.
  • Page 727 9..Brake System MXU 550i Burnishing New Brake Pads Warning: Failure to properly burnish the brake pads could lead to premature brake pad wear or brake loss. Brake loss can result in severe injury. Brake pads (both main and auxiliary) must be burnished to achieve full braking effectiveness.

  • Page 728: Rear Brake Calipers

    9..Brake System MXU 550i Rear Brake Calipers SAFETY FIRST: Protective gloves and eyewear are recommended at this point. NOTE: Brake fluid is a corrosive chemical and can damage paints and some plastics. Avoid contact with skin. There are two rear brake calipers. The caliper that mounts to the top of the final drive gear is connected to the pedal activated master cylinder.
  • Page 729 9..Brake System MXU 550i Remove the side brake caliper from the final drive gear. Brake Pad Replacement Remove the brake pad pins with a 5 mm Allen. 9-39...
  • Page 730 9..Brake System MXU 550i Push in the brake pads and compress the piston. Remove the brake pads. Replace the brake pads if the wear indicators are worn away. Disassembly Remove the brake hose banjo bolt with a 12 mm socket. Remove the banjo bolt and sealing washers.
  • Page 731 9..Brake System MXU 550i Remove the caliper bracket. Remove the rubber boots. Replace if damaged. Remove the brake pad spring. NOTE: Always wear safety glasses when using compressed air and never point it directly at yourself or anyone else. 9-41...
  • Page 732 9..Brake System MXU 550i Place a thick rag over caliper piston and use compressed air to move the piston out. Do not place your fingers over the caliper piston while removing it as serious injury could result. Remove the caliper piston by hand. 9-42...
  • Page 733 9..Brake System MXU 550i Remove the dust seal from the outer caliper bore and discard. Use a mechanics pick to remove the piston seal from the inner caliper bore and discard. 9-43...
  • Page 734 9..Brake System MXU 550i Inspection Check the brake caliper bore for any scratches, damage or excessive wear. Clean the brake caliper bore with DOT 4 brake fluid. Check the piston for any scratches, damage or excessive wear. Clean the piston with DOT 4 brake fluid.
  • Page 735 9..Brake System MXU 550i Check the brake caliper holder for damage. Assembly Coat the new seals, piston, and piston bore with DOT 4 brake fluid. 9-45...
  • Page 736 9..Brake System MXU 550i Install a new piston seal into the inner caliper bore groove. Install the dust seal into the outer groove. Install the piston into the caliper so that the open end faces out. Push the piston all the way 9-46...
  • Page 737 9..Brake System MXU 550i Install the brake pad spring. Install the rubber boots. Apply silicone grease to the caliper bracket pins. Install the caliper bracket. 9-47...

  • Page 738: Brake Pad Installation

    9..Brake System MXU 550i Brake Pad Installation Install the inner brake pad and then the outer brake pad. Install the two the brake pad mounting pins into the caliper and through the brake pads. 9-48...
  • Page 739 9..Brake System MXU 550i Installation Fit the brake caliper into place on the final drive gear case and guide the disc between the pads. Install the two brake calipers mounting bolts (C) and tighten them to specification with a 12 mm socket.
  • Page 740 9..Brake System MXU 550i Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Rear disc holder and gear box 4.5 (45, 34) Brake pad mounting pin 1.8 (18, 13) Brake hose oil bolt 3.5 (35, 25) Top Caliper Removal If the brake caliper is to be disassembled drain the brake fluid (Brake Fluid), and remove the banjo bolt (A) with a 12 mm socket.
  • Page 741 9..Brake System MXU 550i Brake Pad Replacement Push in the brake pads and compress the piston. Remove the brake pads. 9-51...
  • Page 742 9..Brake System MXU 550i Discard the brake pads if the linings are below 1 mm or 0.039 in thick. Disassembly Remove the caliper bracket. Inspect the caliper bracket O-rings and replace them as needed. 9-52...
  • Page 743 9..Brake System MXU 550i Remove the rubber boots. Replace if damaged. NOTE: Always wear safety glasses when using compressed air and never point it directly at yourself or anyone else. Place a thick rag over caliper piston and use compressed air to move the piston out. Do not place your fingers over the caliper piston while removing it as serious injury could result.
  • Page 744 9..Brake System MXU 550i Remove the caliper piston by hand. Remove the dust seal from the caliper bore and discard. 9-54...
  • Page 745 9..Brake System MXU 550i Use a mechanics pick to remove the piston fluid seal from the caliper bore and discard. Inspection Check the brake caliper bore for any scratches, damage or excessive wear. Clean the brake caliper bore with DOT 4 brake fluid. 9-55...
  • Page 746 9..Brake System MXU 550i Check the piston for any scratches, damage or excessive wear. Clean the piston with DOT 4 brake fluid. Assembly Coat the new seals, piston, and piston bore with DOT 4 brake fluid. Install a new piston fluid seal into the inner groove.
  • Page 747 9..Brake System MXU 550i Apply silicone grease to the caliper bracket pins. Install the caliper bracket. Install the brake pads. 9-57...
  • Page 748 9..Brake System MXU 550i Fit the brake caliper into place. Guide the brake disc between the pads. Install the two brake calipers mounting bolts (B) and tighten them to specification with a 12 mm socket. Install new sealing washers and tighten the brake hose banjo bolt (A) to specification with a 12 mm socket.

  • Page 749: Master Cylinders

    9..Brake System MXU 550i Master Cylinders SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Warning: Brake fluid is very caustic and can damage paint, chrome and plastic. Wipe up any spills immediately. Note: The master cylinders can not be repaired. Replace the assembly with a new one if needed.
  • Page 750 9..Brake System MXU 550i To remove the left master cylinder brake light switch take out the screw with a #2 Phillips screwdriver. The right side (front brake) master cylinder has a different style brake switch. Compress the tabs and remove the switch from the master cylinder. 9-60...
  • Page 751 9..Brake System MXU 550i Reservoir Caps Remove the reservoir cap screws with a #2 Phillips screwdriver. Lift off the reservoir cap. 9-61...
  • Page 752 9..Brake System MXU 550i Remove the rubber diaphragm. Master Cylinders If the brake hoses are to be disconnected drain the brake fluid. See the Brake Fluid topic for more information. Remove the brake hose banjo bolt and the two sealing washers. 9-62...

  • Page 753: Brake Levers

    9..Brake System MXU 550i Loosen the brake master cylinder perch bolts with an 8 mm socket. Free the perch from the handlebar and remove the master cylinder. Brake Levers Hold the pivot bolt with a 10 mm socket and loosen the pivot nut with a 10 mm socket. Remove the nut and bolt.

  • Page 754: Installation

    9..Brake System MXU 550i Installation Note: Do not splash brake fluid onto any rubber, plastic and coated parts. When working with brake fluid, use shop towels to cover these parts. Brake Levers Apply a light coat of waterproof grease to the pivot section of the brake lever pivot bolts. Fit the brake lever into place.
  • Page 755 9..Brake System MXU 550i Master Cylinders Fit the master cylinder perch into place on the handlebar. Install the two mounting bolts and tighten them to specification with an 8 mm socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Master cylinder holder bolt 1.2 (12, 7) Secondary master cylinder holder and 1.2 (12, 7)
  • Page 756 9..Brake System MXU 550i When all the brake hoses are connected, fill the master cylinders with fresh brake fluid from a tightly sealed container and bleed the brakes. See the Brake Fluid topic for more information. Make sure the brakes work properly before riding. Reservoir Caps Install the rubber diaphragm (compressed) and the cap.
  • Page 757 9..Brake System MXU 550i Install the reservoir cap screws and tighten them to specification with a #2 Phillips screwdriver. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Master cylinder cap screw 0.15 (1.5, 1.1) Make sure the brakes work properly before riding. Brake Light Switches Install the left master cylinder brake light switch.
  • Page 758 9..Brake System MXU 550i Plug in the rear brake light switch connectors to the switch on the left master cylinder. Insert the right master cylinder brake light switch and be sure it locks into place. 9-68...

  • Page 759: Troubleshooting

    10.Wheels MXU500i Wheels This chapter covers the location and servicing of the wheel components for the KYMCO MXU 700i and MXU 500i models. Wheels and Wheel Hubs ..................10-2 Wheel Bearings ....................10-16 TROUBLESHOOTING Front wheel wobbling • Bent rim •...

  • Page 760: Front Wheel Removal

    10.Wheels MXU500i Wheels and Wheel Hubs SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Front Wheel Removal Break the wheel nuts loose with a 17 mm socket. Use a jack to raise the front wheels off the ground. Remove the four wheel nuts.

  • Page 761: Front Wheel Hub Removal

    10.Wheels MXU500i Front Wheel Hub Removal Remove the cotter pin and discard it. Apply the front brakes and remove the axle nut with a 30 mm socket. Remove the caliper. See the Front Brake Calipers topic for more information. Note: Do not use the front brake while the caliper and brake pads are not installed on the vehicle.

  • Page 762: Front Wheel Hub Installation

    10.Wheels MXU500i Front Wheel Hub Installation Apply grease to the wheel hub splines. Slide on the wheel hub assembly. 12-4...
  • Page 763 10.Wheels MXU500i Thread on the wheel hub nut. Apply the front brakes and tighten the axle nut to specification with a 30 mm socket. Torque Thread dia. Item Kgf-m (N-m, Remarks (mm) ft-lb) Front wheel hub and front 28 (280, 202) Castle nut halfshaft(CVJ) 12-5...

  • Page 764: Front Wheel Installation

    10.Wheels MXU500i Install a new cotter pin and bend it to secure the nut. Front Wheel Installation Place the wheel on the hub. Make sure the tire rotation direction is correct. The arrow indicates the direction in which the tire should turn going forward. 12-6...
  • Page 765 10.Wheels MXU500i Thread on the wheel nuts with their curved side facing toward the wheel. The wheel nuts can only be installed as shown. 12-7...

  • Page 766: Wheel Inspection

    10.Wheels MXU500i Tighten the wheel nuts with a 17 mm socket. Lower the front wheels to the ground and torque the nuts to specification. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Front/rear wheel and hub 6.1 (61, 44) Wheel Inspection Check the wheels for damage.

  • Page 767: Rear Wheel Removal

    10.Wheels MXU500i Rear Wheel Removal Brake the wheel nuts loose a 17 mm socket. Use a jack to raise the rear wheels off the ground. Remove the four wheel nuts. Remove the rear wheel. 12-9...

  • Page 768: Rear Wheel Hub Removal

    10.Wheels MXU500i Rear Wheel Hub Removal Remove the cotter pin and discard it. 12-10...

  • Page 769: Rear Wheel Hub Installation

    10.Wheels MXU500i Apply the rear brakes and remove the axle nut with a 30 mm socket. Slide off the wheel hub assembly. Rear Wheel Hub Installation Apply grease to the wheel hub splines. 12-11...
  • Page 770 10.Wheels MXU500i Slide on the wheel hub assembly. Thread on the wheel hub nut. 12-12...
  • Page 771 10.Wheels MXU500i Apply the rear brakes and tighten the axle nut to specification with a 30 mm socket. Torque Thread dia. Item Kgf-m (N-m, Remarks (mm) ft-lb) Rear wheel hub and rear Castle 28 (280, 202) halfshaft(CVJ) Install a new cotter pin and bend it to secure the nut. 12-13...

  • Page 772: Rear Wheel Installation

    10.Wheels MXU500i Rear Wheel Installation Place the wheel on the hub. Make sure the tire rotation direction is correct. The arrow indicates the direction in which the tire should turn going forward. Thread on the wheel nuts with their curved side facing toward the wheel. 12-14...
  • Page 773 10.Wheels MXU500i The wheel nuts can only be installed as shown. Tighten the wheel nuts with a 17 mm socket. Lower the rear wheels to the ground and torque the nuts to specification. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Front/rear wheel and hub 6.1 (61, 44) 12-15...

  • Page 774: Wheel Bearings

    10.Wheels MXU500i Wheel Bearings SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Front Bearings Remove the front wheels. See the Wheels and Wheel Hubstopic for more information. Remove the steering knuckle. See the Steering Knuckles topic for more information. Check that the bearings rotate smoothly and do not bind.
  • Page 775 10.Wheels MXU500i Drive the bearing out with a bearing driver tool from the inside out. Heat the area around the bearing to aid in removal and use a press if available. Remove the bearing. Note: Place the new bearing in a freezer for at least a half hour before installation. Heat the knuckle.
  • Page 776 10.Wheels MXU500i Fit the bearing into place. Support the knuckle so that it sits level. Drive in a new bearing with a suitable driver with the same outside diameter as the bearing. Use a press if available. The manufactures markings on the bearing must face out. 12-18...
  • Page 777 10.Wheels MXU500i Install the snap ring with a pair of snap ring pliers. Be sure it fits securely into its groove. Install the steering knuckle. See the Steering Knuckles topic for more information. Install the front wheels and hubs. See the Wheels and Wheel Hubs topic for more information.
  • Page 778 10.Wheels MXU500i Inspect the knuckle bearing by turning it with a finger if the bearing doesn't turn smoothly it must be replaced. Remove the bearing snap ring with snap ring pliers. Drive out the bearing from the half shaft side of the knuckle. Heat the knuckle around the bearing to aid removal.
  • Page 779 10.Wheels MXU500i Place the new knuckle bearing in a freezer for at least a half hour before installation. Heat the knuckle around the bearing cavity to aid installation. Drive in the new knuckle bearing from the wheel hub side of the knuckle. Install the new bearing retainer snap ring into the groove with snap ring pliers.
  • Page 780 11.Steering MXU 550i Steering This chapter covers the location and servicing of the steering components for the KYMCO MXU 550i models. Handlebar ......................11-2 Steering Knuckles ....................11-20 Steering Shaft ...................... 11-24 Tie-Rods ......................11-32 Hard Steering (Heavy) • Insufficient tire pressure Steers to one side or does not track straight •...

  • Page 781: Brake Master Cylinders

    11.Steering MXU 550i Handlebar SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Instrument Display and Cover See the Instrument Cover topic. Brake Master Cylinders See the Master Cylinders topic. Bar-Ends Loosen the bar-end screw with a 6 mm Allen. 11-2...
  • Page 782 11.Steering MXU 550i Remove the bar-end and weight from the handlebar. Throttle and Switchgear Remove the front fender upper cover. See the Front Fender topic for more information. Free the wire bands from the handlebar. 11-3...
  • Page 783 11.Steering MXU 550i Remove the three throttle cover screws with a #2 Phillips screwdriver. Lift off the throttle housing cover. 11-4...
  • Page 784 11.Steering MXU 550i Free the end of throttle cable from the throttle lever. Unscrew the throttle cable from the throttle housing. 11-5...
  • Page 785 11.Steering MXU 550i Unplug the 2WD/4WD switch connector. Remove the two throttle mounting screws with a #2 Phillips screwdriver. Separate the throttle perch from the handlebar. Unplug the left handlebar switch connectors. 11-6...
  • Page 786 11.Steering MXU 550i Loosen the switch housing screws with a #2 Phillips screwdriver. Free the left switchgear from the handlebar. 11-7...
  • Page 787 11.Steering MXU 550i Handlebar Free the cables, hoses, and wires from the guides and wire bands. Remove the four handlebar clamp bolts. 11-8...
  • Page 788 11.Steering MXU 550i Lift off the instrument bracket. Lift off the handlebar clamps. 11-9...
  • Page 789 11.Steering MXU 550i Lift off the handlebar. Grips If you plan to replace the grips you can slice them lengthwise with a razor blade and peel them off. To remove the grips without cutting them grip end bolts, then use a screwdriver to open a gap between the grip and the handlebar.

  • Page 790: Installation

    11.Steering MXU 550i NOTE: Always wear safety glasses when using compressed air and never point it directly at yourself or anyone else. Before installing the grips to the handlebar, wipe down the area with a brake or parts cleaner that will dry without leaving a residue. When you are sure the area is dry apply grip cement to the bar or tube.
  • Page 791 11.Steering MXU 550i Set the handlebar clamps into place. Set the instrument bracket into place. 11-12...
  • Page 792 11.Steering MXU 550i Install the four handlebar clamp bolts. Make sure the handlebar is positioned so that the punch mark lines up as shown. 11-13...
  • Page 793 11.Steering MXU 550i Tighten the handlebar clamp bolts evenly to specification with a 12 mm socket. TORQUE ITEM THREAD SIZE AND TYPE kgf-m Nm ft-lb HANDLEBAR AND STEERING POST M8 X 1.25 2.4-3.2 24-32 20 Route the cables, hoses, and wires through the guides and secure them with the wire bands as shown.
  • Page 794 11.Steering MXU 550i Throttle and Switchgear Fit the left switch gear onto the handlebar. Guide the post into its hole. Install the two switch gear housing screws and tighten them securely with a #2 Phillips screwdriver. 11-15...
  • Page 795 11.Steering MXU 550i Plug in the left handlebar switch connectors. Fit the throttle housing and 2WD/4WD switch into place. Install the two throttle housing perch screws and tighten them securely with a #2 Phillips screwdriver. 11-16...
  • Page 796 11.Steering MXU 550i Thread the throttle cable into the throttle housing. Connect the end of the throttle cable to the throttle lever. 11-17...
  • Page 797 11.Steering MXU 550i Plug in the 2WD/4WD switch connector. Install the throttle housing cover. Install the three throttle housing cover screws and tighten them securely. Secure the wires to the handlebar with wire bands as shown. 11-18...

  • Page 798: Master Cylinders

    11.Steering MXU 550i Bar-Ends Slide the bar-end and weight into the handlebar. Tighten the bar-end screw with a 6 mm Allen to secure the bar-end. Master Cylinders See the Master Cylinders topic. Instrument Display and Cover See the Instrument Cover topic.

  • Page 799: Steering Knuckles

    11.Steering MXU 550i Steering Knuckles SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Make sure the vehicle is securely supported with the front end off the ground. Remove the front wheels and hubs. See the Wheels and Wheel Hubs topic for more information.
  • Page 800 11.Steering MXU 550i Remove the steering knuckle from the upper and lower A-arms. Use the ball joint separator tool to separate the suspension arm joints from the knuckle if needed. Note: Use a ball joint remover if needed. To remove the front drive shafts see the Drive Shafts topic.
  • Page 801 11.Steering MXU 550i Installation Install the steering knuckle onto the drive shaft, upper and lower A-arms. Guide the A-arm ball joint into the knuckle at the bottom. Install the two steering knuckle bolts and tighten to specification with a 14 mm socket. 11-22...
  • Page 802 11.Steering MXU 550i TORQUE THREAD SIZE AND ITEM TYPE kgf-m Nm ft-lb FRONT KNUCKLE AND FRONT M10 X1.25 48 34 UPPER/LOVER ARM Install the tie rod ends into the steering knuckles. See the Tie Rods topic for more information. Install the front wheels and hubs. See the Wheels and Wheel Hubs topic for more information.

  • Page 803: Steering Shaft

    11.Steering MXU 550i Steering Shaft SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove these components Component Topic Front rack Racks Side covers Side Covers Fuel tank Fuel Tank Mudguards Mudguards and Footrests Front fender Front Fender Handlebar Handlebar Open the guide and free the wires, throttle cable and brake hoses.
  • Page 804 11.Steering MXU 550i Free the inner ends of the tie-rods from the steering shaft. See the Tie-Rods topic for more information. Loosen and remove the two steering shaft bushing bolts with a 10 mm socket. Remove the steering shaft bushing cap and the bushing. 11-25...
  • Page 805 11.Steering MXU 550i Remove the two steering shaft bearing flange bolts with a 12 mm socket. Lift the steering shaft up and free the bearing from the frame. 11-26...
  • Page 806 11.Steering MXU 550i Lift the steering shaft up and out of the frame. Inspect the steering shaft for bends and damage. If the steering shaft bearing needs to be replace remove the bolt with a 14 mm socket. 11-27...
  • Page 807 11.Steering MXU 550i Installation Install the bearing plate, bearing, washer and bolt. Tighten the bolt to specification with a 14 mm socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Steering post lower pivot 5.5 (55, 40) 11-28...
  • Page 808 11.Steering MXU 550i Fit the steering shaft into place. Guide the bearing into its socket in the frame. Thread in the steering shaft bearing flange bolts. Tighten the bolts to specification with a 12 mm socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Bearing flange and frame 2.8 (28, 20)
  • Page 809 11.Steering MXU 550i Lubricate the steering shaft bushing with waterproof grease. Install the bushing. Install the bushing cap and the two steering shaft bushing bolts. 11-30...
  • Page 810 11.Steering MXU 550i Tighten the steering shaft bushing bolts securely with a 10 mm socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Upper/lower housing and frame 2.7 (27, 19) Route the wires, throttle cable and brake hoses through the guide and close the guide. 11-31...
  • Page 811 11.Steering MXU 550i Connect the inner ends of the tie-rods to the steering shaft. See the Tie-Rods topic for more information. Check the toe-in. See the Suspension and Steering Inspection topic for more information. Install these components Component Topic Front fender Front Fender Front rack Racks...
  • Page 812 11.Steering MXU 550i Remove the cotter pin from the outer tie-rod nut and discard it. Hold the tie-rod joint with a 14 mm wrench and loosen the nut with a 17 mm socket. Remove the tie-rod end nut. Free the tie-rod end from the steering knuckle. 11-33...
  • Page 813 11.Steering MXU 550i Use the special ball joint separator tool if needed to separate the end of the tie-rod form the knuckle If needed. Remove the cotter pin from the inner tie-rod nut and discard it. Hold the tie-rod joint with a 14 mm wrench and loosen the nut with a 17 mm socket. Free the inner tie-rod joint from the steering shaft.
  • Page 814 11.Steering MXU 550i Inspect the tie-rods for damage. Make sure the joint boots are in good condition and the joints move smoothly. Replace the joints and boots as needed if they are in poor condition. Both ends of the tie-rod should have the same amount of threads showing. 11-35...
  • Page 815 11.Steering MXU 550i Installation Fit the tie-rod into place. The adjuster flat on the tie rod should sit on the outside. 11-36...
  • Page 816 11.Steering MXU 550i Thread on the inner tie-rod joint nut. Hold the inner tie-rod joint with a 14 mm wrench and tighten the nut to specification with a 17 mm socket. Install a new cotter pin and bend it to secure the nut.
  • Page 817 11.Steering MXU 550i Hold the tie-rod joint with a 14 mm wrench and tighten the nut to specification with a 17 mm socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Steering knuckle and tie-rod 4.2 (42, 30) Install a new cotter pin onto the tie-rod joint nut. Install the front wheels and hubs.
  • Page 818 11.Steering MXU 550i Steering This chapter covers the location and servicing of the steering components for the KYMCO MXU 550i models. Handlebar ......................11-2 Steering Knuckles ....................11-20 Steering Shaft ...................... 11-24 Tie-Rods ......................11-32 Hard Steering (Heavy) • Insufficient tire pressure Steers to one side or does not track straight •...
  • Page 819 11.Steering MXU 550i Handlebar SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Instrument Display and Cover See the Instrument Cover topic. Brake Master Cylinders See the Master Cylinders topic. Bar-Ends Loosen the bar-end screw with a 6 mm Allen. 11-2...
  • Page 820 11.Steering MXU 550i Remove the bar-end and weight from the handlebar. Throttle and Switchgear Remove the front fender upper cover. See the Front Fender topic for more information. Free the wire bands from the handlebar. 11-3...
  • Page 821 11.Steering MXU 550i Remove the three throttle cover screws with a #2 Phillips screwdriver. Lift off the throttle housing cover. 11-4...
  • Page 822 11.Steering MXU 550i Free the end of throttle cable from the throttle lever. Unscrew the throttle cable from the throttle housing. 11-5...
  • Page 823 11.Steering MXU 550i Unplug the 2WD/4WD switch connector. Remove the two throttle mounting screws with a #2 Phillips screwdriver. Separate the throttle perch from the handlebar. Unplug the left handlebar switch connectors. 11-6...
  • Page 824 11.Steering MXU 550i Loosen the switch housing screws with a #2 Phillips screwdriver. Free the left switchgear from the handlebar. 11-7...
  • Page 825 11.Steering MXU 550i Handlebar Free the cables, hoses, and wires from the guides and wire bands. Remove the four handlebar clamp bolts. 11-8...
  • Page 826 11.Steering MXU 550i Lift off the instrument bracket. Lift off the handlebar clamps. 11-9...
  • Page 827 11.Steering MXU 550i Lift off the handlebar. Grips If you plan to replace the grips you can slice them lengthwise with a razor blade and peel them off. To remove the grips without cutting them grip end bolts, then use a screwdriver to open a gap between the grip and the handlebar.

  • Page 828: Installation

    11.Steering MXU 550i NOTE: Always wear safety glasses when using compressed air and never point it directly at yourself or anyone else. Before installing the grips to the handlebar, wipe down the area with a brake or parts cleaner that will dry without leaving a residue. When you are sure the area is dry apply grip cement to the bar or tube.
  • Page 829 11.Steering MXU 550i Set the handlebar clamps into place. Set the instrument bracket into place. 11-12...
  • Page 830 11.Steering MXU 550i Install the four handlebar clamp bolts. Make sure the handlebar is positioned so that the punch mark lines up as shown. 11-13...
  • Page 831 11.Steering MXU 550i Tighten the handlebar clamp bolts evenly to specification with a 12 mm socket. TORQUE ITEM THREAD SIZE AND TYPE kgf-m Nm ft-lb HANDLEBAR AND STEERING POST M8 X 1.25 2.4-3.2 24-32 20 Route the cables, hoses, and wires through the guides and secure them with the wire bands as shown.
  • Page 832 11.Steering MXU 550i Throttle and Switchgear Fit the left switch gear onto the handlebar. Guide the post into its hole. Install the two switch gear housing screws and tighten them securely with a #2 Phillips screwdriver. 11-15...
  • Page 833 11.Steering MXU 550i Plug in the left handlebar switch connectors. Fit the throttle housing and 2WD/4WD switch into place. Install the two throttle housing perch screws and tighten them securely with a #2 Phillips screwdriver. 11-16...
  • Page 834 11.Steering MXU 550i Thread the throttle cable into the throttle housing. Connect the end of the throttle cable to the throttle lever. 11-17...
  • Page 835 11.Steering MXU 550i Plug in the 2WD/4WD switch connector. Install the throttle housing cover. Install the three throttle housing cover screws and tighten them securely. Secure the wires to the handlebar with wire bands as shown. 11-18...
  • Page 836 11.Steering MXU 550i Bar-Ends Slide the bar-end and weight into the handlebar. Tighten the bar-end screw with a 6 mm Allen to secure the bar-end. Master Cylinders See the Master Cylinders topic. Instrument Display and Cover See the Instrument Cover topic.
  • Page 837 11.Steering MXU 550i Steering Knuckles SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Make sure the vehicle is securely supported with the front end off the ground. Remove the front wheels and hubs. See the Wheels and Wheel Hubs topic for more information.
  • Page 838 11.Steering MXU 550i Remove the steering knuckle from the upper and lower A-arms. Use the ball joint separator tool to separate the suspension arm joints from the knuckle if needed. Note: Use a ball joint remover if needed. To remove the front drive shafts see the Drive Shafts topic.
  • Page 839 11.Steering MXU 550i Installation Install the steering knuckle onto the drive shaft, upper and lower A-arms. Guide the A-arm ball joint into the knuckle at the bottom. Install the two steering knuckle bolts and tighten to specification with a 14 mm socket. 11-22...
  • Page 840 11.Steering MXU 550i TORQUE THREAD SIZE AND ITEM TYPE kgf-m Nm ft-lb FRONT KNUCKLE AND FRONT M10 X1.25 48 34 UPPER/LOVER ARM Install the tie rod ends into the steering knuckles. See the Tie Rods topic for more information. Install the front wheels and hubs. See the Wheels and Wheel Hubs topic for more information.
  • Page 841 11.Steering MXU 550i Steering Shaft SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Remove these components Component Topic Front rack Racks Side covers Side Covers Fuel tank Fuel Tank Mudguards Mudguards and Footrests Front fender Front Fender Handlebar Handlebar Open the guide and free the wires, throttle cable and brake hoses.
  • Page 842 11.Steering MXU 550i Free the inner ends of the tie-rods from the steering shaft. See the Tie-Rods topic for more information. Loosen and remove the two steering shaft bushing bolts with a 10 mm socket. Remove the steering shaft bushing cap and the bushing. 11-25...
  • Page 843 11.Steering MXU 550i Remove the two steering shaft bearing flange bolts with a 12 mm socket. Lift the steering shaft up and free the bearing from the frame. 11-26...
  • Page 844 11.Steering MXU 550i Lift the steering shaft up and out of the frame. Inspect the steering shaft for bends and damage. If the steering shaft bearing needs to be replace remove the bolt with a 14 mm socket. 11-27...
  • Page 845 11.Steering MXU 550i Installation Install the bearing plate, bearing, washer and bolt. Tighten the bolt to specification with a 14 mm socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Steering post lower pivot 5.5 (55, 40) 11-28...
  • Page 846 11.Steering MXU 550i Fit the steering shaft into place. Guide the bearing into its socket in the frame. Thread in the steering shaft bearing flange bolts. Tighten the bolts to specification with a 12 mm socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Bearing flange and frame 2.8 (28, 20)
  • Page 847 11.Steering MXU 550i Lubricate the steering shaft bushing with waterproof grease. Install the bushing. Install the bushing cap and the two steering shaft bushing bolts. 11-30...
  • Page 848 11.Steering MXU 550i Tighten the steering shaft bushing bolts securely with a 10 mm socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Upper/lower housing and frame 2.7 (27, 19) Route the wires, throttle cable and brake hoses through the guide and close the guide. 11-31...
  • Page 849 11.Steering MXU 550i Connect the inner ends of the tie-rods to the steering shaft. See the Tie-Rods topic for more information. Check the toe-in. See the Suspension and Steering Inspection topic for more information. Install these components Component Topic Front fender Front Fender Front rack Racks...
  • Page 850 11.Steering MXU 550i Remove the cotter pin from the outer tie-rod nut and discard it. Hold the tie-rod joint with a 14 mm wrench and loosen the nut with a 17 mm socket. Remove the tie-rod end nut. Free the tie-rod end from the steering knuckle. 11-33...
  • Page 851 11.Steering MXU 550i Use the special ball joint separator tool if needed to separate the end of the tie-rod form the knuckle If needed. Remove the cotter pin from the inner tie-rod nut and discard it. Hold the tie-rod joint with a 14 mm wrench and loosen the nut with a 17 mm socket. Free the inner tie-rod joint from the steering shaft.
  • Page 852 11.Steering MXU 550i Inspect the tie-rods for damage. Make sure the joint boots are in good condition and the joints move smoothly. Replace the joints and boots as needed if they are in poor condition. Both ends of the tie-rod should have the same amount of threads showing. 11-35...
  • Page 853 11.Steering MXU 550i Installation Fit the tie-rod into place. The adjuster flat on the tie rod should sit on the outside. 11-36...
  • Page 854 11.Steering MXU 550i Thread on the inner tie-rod joint nut. Hold the inner tie-rod joint with a 14 mm wrench and tighten the nut to specification with a 17 mm socket. Install a new cotter pin and bend it to secure the nut.
  • Page 855 11.Steering MXU 550i Hold the tie-rod joint with a 14 mm wrench and tighten the nut to specification with a 17 mm socket. Torque Item Thread dia. (mm) Kgf-m (N-m, ft-lb) Steering knuckle and tie-rod 4.2 (42, 30) Install a new cotter pin onto the tie-rod joint nut. Install the front wheels and hubs.

  • Page 856: Front Suspension

    13.Front Suspension MXU550i Front Suspension This chapter covers the location and servicing of the front suspension components for the KYMCO MXU 550i models. A-arms ........................13-2 Front Shock Absorbers ..................13-10 TROUBLESHOOTING Hard steering (heavy) • Insufficient tire pressure Steers to one side or does not track straight •...
  • Page 857 13.Front Suspension MXU550i A-arms SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Inspection Move the suspension arms up and down. Also, try to move them front to back. If there is excessive play or noise, the bushings may need to be replaced. Removal Remove these components Component...
  • Page 858 13.Front Suspension MXU550i Remove the brake hose stay and free the brake hoses from the upper A-arms. The lower A-arms have two pivot bolts and nuts. The upper A-arms have a single pivot bolt and nut. Hold the bolt with a 14 mm wrench and loosen the nut with a 17 mm socket. Remove the A-arm pivot bolts and nuts.

  • Page 859: Bushing Replacement

    13.Front Suspension MXU550i Bushing Replacement Upper A-arm Remove the dust seals from the upper A-arm pivots. Remove the collars. Inspect the collars and bushings. Remove the bushings with a suitable bearing puller, or tap them out using a drift pin and a hammer.
  • Page 860 13.Front Suspension MXU550i Press in the new bushings with a press, or tap them in with a soft-blow hammer. Lower A-arm Remove the dust seals from the lower A-arm pivots. Remove the collars. Inspect the collars and bushings. Remove the bushings with a suitable bearing puller or tap the bushings out with a drift pin and hammer.
  • Page 861 13.Front Suspension MXU550i Knuckle Ends Check the knuckle ball joint boot for wear or damage and replace as needed. Remove the snap with snap ring pliers on the back of the ball joint. 13-6...
  • Page 862 13.Front Suspension MXU550i Support the A-arm with a suitable tool as shown that will allow room for the ball joint to fall out. Press out the ball joint. Clean the ball joint mount in the A-arm. Apply green Loctite #609 to the entire outside diameter of the bail joint. Support the A-arm with a suitable tool as shown that will allow room for the ball joint to be installed.
  • Page 863 13.Front Suspension MXU550i Install the new snap ring on the back of the knuckle end with snap ring pliers. Be sure the snap ring sits in the groove properly. Installation Use new locknuts with the suspension pivot bolts. Install the collars and dust seals. Be sure to return the A-arms to their correct positions.
  • Page 864 13.Front Suspension MXU550i Install the A-arms. The ball joints must face up on the lower arms and down on the upper arms. Insert the A-arm mounting bolts from the front. Hold the bolts with a 14 mm socket and tighten the nuts to specification with a 17 mm socket. TORQUE ITEM THREAD SIZE AND TYPE...

  • Page 865: Front Shock Absorbers

    13.Front Suspension MXU550i Front Shock Absorbers SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Preload The shock absorbers have adjustable preload collars, just like the rear shocks. Turn the preload collar with a pin spanner to adjust the spring preload. Increase the amount of preload for heavy loads.
  • Page 866 13.Front Suspension MXU550i Remove the front wheels. See the Wheels and Wheel Hubs topic for more information. Note: The front shock absorber removal procedure is the same for both sides. Hold the lower shock absorber mounting bolt with a 14 mm wrench and loosen the nut with a 17 mm socket.
  • Page 867 13.Front Suspension MXU550i Inspection Inspect the shock absorber for damage, leaks or other wear. Replace the shock absorber with a new one as needed. Installation Use new locknuts with the suspension pivot bolts. Install the shock absorber. 13-12...
  • Page 868 13.Front Suspension MXU550i Install the upper and lower mounting bolts and nuts. Insert the bolts from the front. Hold the upper shock absorber mounting bolt with a 14 mm wrench and tighten the nut to specification with a 17 mm socket. Hold the lower shock absorber mounting bolt with a 14 mm wrench and tighten the nut to specification with a 17 mm socket.

  • Page 869: Rear Suspension

    14.Rear Suspension MXU550i Rear Suspension This chapter provides the rear suspension specifications for the KYMCO MXU 550i models. Rear Shock Absorbers.................... 14-2 Rear Suspension Arms ................... 14-5 TROUBLESHOOTING Soft rear shock absorber • Weak shock absorber spring • Faulty damper...

  • Page 870: Rear Shock Absorbers

    14.Rear Suspension MXU550i Rear Shock Absorbers SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Preload The shock absorbers have adjustable preload collars. Turn the preload collar with a pin spanner to adjust the spring preload. Increase the amount of preload for heavy loads. Removal Support the back of the frame so that the vehicles weight is not resting on the rear suspension.
  • Page 871 14.Rear Suspension MXU550i The rear shock absorbers are mounted to the frame and the lower suspension arms. Hold the rear shock absorber mounting bolts with a 14 mm socket and loosen the nuts with a 17 mm socket. Remove the upper and lower shock absorber mounting nuts and bolts. Remove the shock absorber.
  • Page 872 14.Rear Suspension MXU550i Inspection Inspect the shock absorber for damage and leaks. Replace as needed. Installation Use new locknuts with the suspension pivot bolts. Install the shock absorber. Insert the rear shock absorber mounting bolts from the front. Thread on the nuts. Hold the shock absorber mounting bolts with a 14 mm socket and tighten the nuts to specification with a 17 mm socket.
  • Page 873 14.Rear Suspension MXU550i Rear Suspension Arms SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Removal Support the back of the frame so that the vehicle weight is not resting on the rear suspension. Remove the rear wheels and hubs. See the Wheels and Wheel Hubs topic for more information.
  • Page 874 14.Rear Suspension MXU550i Remove the tie-rods. Note their locations so they can be returned to their original positions. Remove the two bolts for each stabilizer bushing mount. Remove the stabilizer bar and bushings. 14-6...
  • Page 875 14.Rear Suspension MXU550i Insect the tie rod ball joints and boots for wear and damage. Move the ball joint by hand and make sure it moves smoothly. Replace the stabilizer ball joint as needed. Inspect the stabilizer bar and bushings. Replace the components as needed. Rear Knuckles Remove the rear brake caliper.
  • Page 876 14.Rear Suspension MXU550i The rear knuckles mount to the A-arms with a nut and bolt at the top and bottom. Hold the rear knuckle arm bolts with a 14 mm wrench and loosen the nuts with a 17 mm socket. Remove the rear knuckle nuts and bolts.
  • Page 877 14.Rear Suspension MXU550i Inspect the knuckle and bearing. Knuckle Bearing Replacement To replace the bearings, see the Wheel Bearings topic for more information. Rear Suspension Arms Move the suspension arms up and down. Also, try to move them front to back. If there is excessive play, the bushings may need to be replaced.
  • Page 878 14.Rear Suspension MXU550i Remove the pivot bolts and nuts. Remove both suspension arms in the same manner. Inspect suspension arms for signs of damage. Remove the dust seals and collars. 14-10...
  • Page 879 14.Rear Suspension MXU550i Inspect the bushings and collars. Replace the bushings as needed. Replace the bushings in the same manner as the front A-arms. See the A-arms topic for more information. Installation Use new locknuts with the suspension pivot bolts. Rear Suspension Arms 14-11...
  • Page 880 14.Rear Suspension MXU550i Install the pivot collars and dust seals. Fit the rear suspension arms into place. Install all of the pivot bolts from the front and thread on the nuts. Hold the bolts with a 14 mm socket and tighten the nuts to specification with a 17 mm socket.
  • Page 881 14.Rear Suspension MXU550i Rear Knuckles Grease the drive shaft splines. Fit the knuckle into place in its original position. Guide the half shaft through the bearing in the knuckle. Insert the rear knuckle bolts from the front and thread on the nuts. Hold the bolts with a 14 mm wrench and tighten the nuts to specification with a 17 mm socket.
  • Page 882 14.Rear Suspension MXU550i Stabilizer Bar / Sway Bar Fit the stabilizer bar and bushings into place. Install the two bolts for each stabilizer bushing mount. ITEM kgf-m ft-lb Stabilizer and frame 14-14...
  • Page 883 14.Rear Suspension MXU550i Fit the stabilizer tie-rods into place in their original positions. Thread on new tie-rod nuts. Hold the tie-rod joints with a 12 mm socket and tighten the nuts to specification with a 17 mm socket. ITEM kgf-m ft-lb Stabilizer tie-rod joint nut Install the shock absorbers.
  • Page 884 15.Electrical System MXU 550i Electrical Systems This chapter covers the location and servicing of the electrical systems for the KYMCO MXU 550i models. CHARGING SYSTEM AND BATTERY ....................4 CAUTION..........................4 GENERAL INSTRUCTIONS ..................... 5 TROUBLESHOOTING ......................6 IGNITION SYSTEM ......................... 7 GENERAL INSTRUCTIONS .....................
  • Page 885 15.Electrical System MXU 550i Fuse Box ............................. 26 Main Fuse ........................... 28 Relays ............................29 Ignition System ........................... 31 Electrical Connections ........................ 31 Troubleshooting ......................... 32 Spark Check ..........................32 Ignition Coil ..........................33 Primary Resistance ......................33 Spark Plug Cap Resistance ....................34 Ignition Coil Peak Voltage ....................
  • Page 886 15.Electrical System MXU 550i Fuse ............................ 59 Voltage Inspection ......................60 Continuity Inspection ......................61 Removal ..........................61 Installation .......................... 62 Switches ............................. 64 Ignition Switch ..........................64 Left Handlebar Switches ......................65 Light Switch ........................66 Engine Start Switch ......................66 Engine Kill Switch .......................

  • Page 887: Electrical System

    15.Electrical System MXU 550i CHARGING SYSTEM AND BATTERY CAUTION • The battery gives off explosive gases; keep sparks, flames and cigarettes away. Provide adequate ventilation when charging. • The battery contains sulfuric acid (electrolyte). Contact with skin or eyes may cause severe burns.

  • Page 888: General Instructions

    15.Electrical System MXU 550i GENERAL INSTRUCTIONS • Always turn off the ignition switch before disconnecting any electrical component. • Some electrical components may be damaged if terminals or connectors are connected or disconnected while the ignition switch is tinned to "ON" and current is present. •...

  • Page 889: Troubleshooting

    15.Electrical System MXU 550i TROUBLESHOOTING Problem: Magneto does not charge Condition Remedy 1. Lead wires/connections shorted - loose - 1. Repair - replace - tighten lead open wires 2. Magneto coils shorted - grounded - open 2. Replace magneto coils 3.

  • Page 890: Ignition System

    15.Electrical System MXU 550i — Seal the battery properly — Never open the seals again • For battery charging, do not exceed the charging current and time specified on the battery. Using excessive current or extending the charging time may damage the battery. IGNITION SYSTEM GENERAL INSTRUCTIONS •...

  • Page 891: Starting System

    15.Electrical System MXU 550i Peak voltage is normal, but no spark jumps at the plug • Faulty spark plug or leaking ignition coil secondary current. • Faulty ignition coil. Starting System GENERAL INSTRUCTIONS • Always turn the ignition switch to "OFF" before servicing the starter motor. The motor could suddenly start, causing serious injury.

  • Page 892: Lights, Switches, And Fuel Pump

    15.Electrical System MXU 550i • Starter motor rotates in reverse • Weak battery LIGHTS, SWITCHES, AND FUEL PUMP GENERAL INSTRUCTIONS • Note the following when replacing the halogen headlight bulb Wear clean gloves while replacing the bulb. Do not put finger prints on the headlight bulb, as they may create hot spots on the bulb and cause it to fail.

  • Page 893: Electrical Specifications

    15.Electrical System MXU 550i Electrical Specifications ITEM SPECIFICATIONS Capacity 12V - 18 Ah Current leakage 0.5 Ma max. Full charged 13.0 - 13.2 V Battery Voltage (20°C/68°F) Needs charging Below 12.3 V Normal 1.8 A/5 - 10 h Charging current Quick 9 A/1 h Capacity MXU 500i...

  • Page 894: Battery

    15.Electrical System MXU 550i Battery SAFETY FIRST: Protective gloves and eyewear are recommended at this point. General Information ITEM SPECIFICATIONS Capacity 12V-18 Ah Current leakage 0.5 Ma max. Full charge 13.0 - 13.2 V Battery Voltage (20°C/68°F) Needs charging Below 12.3 V Normal 1.8 A/5 - 10 h Charging current...
  • Page 895 15.Electrical System MXU 550i Turn OFF the ignition switch. Free the rubber strap from the hooks. Remove the negative battery cable (black) first with a #3 Phillips or 10 mm socket. Remove the positive battery cable (red) after the negative battery cable has been removed with a #3 Phillips or 10 mm socket.
  • Page 896 15.Electrical System MXU 550i Free the winch cables along with the battery cables if the vehicle is equipped with a winch. Lift out the battery. 15-13...

  • Page 897: Testing

    15.Electrical System MXU 550i Testing Voltage Check the battery voltage with a multimeter set to read DC voltage (DCV). Place the positive probe onto the positive battery terminal and the negative probe to the negative battery terminal. If the battery reads under 12.3 V it is undercharged. Full charged 13.0 - 13.2 V Battery Voltage (20°C/68°F)

  • Page 898: Charging System Testing

    15.Electrical System MXU 550i Current flow higher than the range selected may blow out the fuse in the tester. While measuring current, do not turn the ignition switch ON. A sudden surge of current may blow out the fuse in the tester. If current leakage exceeds the specified value, a short circuit is likely.

  • Page 899: Installation

    15.Electrical System MXU 550i Installation Install the battery. Install the winch leads with their corresponding battery cables if a winch is installed.Connect the positive cable to the positive batter terminal and thread in the terminal screw. Tighten the screw securely with a #3 Phillips or 10 mm socket. Place the negative lead over the negative batter terminal and thread in the screw.
  • Page 900 15.Electrical System MXU 550i Install the battery strap. Install the seat. See the Seat topic for more information. 15-17...

  • Page 901: Charging System

    15.Electrical System MXU 550i Charging System SAFETY FIRST: Protective gloves and eyewear are recommended at this point. ITEM SPECIFICATIONS Alternator Capacity 310 - 400 W/5000 rpm Charging coil resistance (20°C/68°F) 0.1 - 0.3 Ω Stator Coil Resistance Less than 1 ohm (yellow to yellow) AC Generator (no load) Output 60 AC volts @ 3000 RPM (black to black) You will need a digital multimeter (Fluke model 73) to inspect the charging system.

  • Page 902: Stator Coil

    15.Electrical System MXU 550i Turn on the lights and turn the dimmer switch to "HI". Rev the engine to 5,000 rpm and measure the voltage. The voltage should be greater than the battery voltage, and no more than 15.0 V. The standard at 5,000 rpm is 14.0 ± 1 V. Turn the ignition switch off before disconnecting any charging system components.

  • Page 903: Regulator/Rectifier

    15.Electrical System MXU 550i Regulator/Rectifier Inspection Connectors Inspect the connections of the regulator/rectifier connectors. Inspect the connectors for loose wires and corroded terminals. Battery Line Unplug the four pin regulator/rectifier connector with the green, black, and red/white wires. Set the multimeter to read DC voltage (DCV). Measure the voltage between the Red/White wire terminal on the harness side of the connector and a ground.
  • Page 904 15.Electrical System MXU 550i Voltage Feedback Line Unplug the four pin regulator/rectifier connector with the green, black, and red/white wires. Set the multimeter to read DC voltage (DCV). Measure the voltage between the black wire terminal on the harness side of the connector and a ground.

  • Page 905: Removal

    15.Electrical System MXU 550i Ground Line Unplug the four pin regulator/rectifier connector with the green, black, and red/white wires. Set the multimeter to read ohms of resistance (Ω). Check the continuity between the Green wire terminal and ground. There should be continuity at all times.
  • Page 906 15.Electrical System MXU 550i Unplug the regulator/rectifier connectors. Remove the two regulator/rectifier bracket nuts. Remove the regulator/rectifier and bracket. Remove the two bolts to free the regulator/rectifier from the bracket. 15-23...

  • Page 907: Installation

    15.Electrical System MXU 550i Installation Install the regulator/rectifier to the bracket and tighten the two bolts securely. Fit the bracket into place on the right side of the frame. Install the two regulator/rectifier bracket mounting nuts and tighten them securely. 15-24...
  • Page 908 15.Electrical System MXU 550i Plug in the regulator/rectifier connectors and secure them to the bracket. Install the front fender. See the Front Fender topic for more information. 15-25...

  • Page 909: Fuses And Relays

    15.Electrical System MXU 550i Fuses and Relays SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Turn the ignition switch to the OFF position before unplugging relays or fuses. Fuse Box Remove the seat. See the Seat topic for more information. The fuse box is located near the battery under the seat.
  • Page 910 15.Electrical System MXU 550i Remove the fuse box cover. The cover has labels for the fuse slots. 15-27...

  • Page 911: Main Fuse

    15.Electrical System MXU 550i Check for blown fuses and replace them as needed. The fuse must be replaced with a new item with the same amp rating. Main Fuse The main fuse is located with the starter relay. See the Starting System topic for more information on checking this fuse.

  • Page 912: Relays

    15.Electrical System MXU 550i Relays The fan (A), engine start (B), fuel pump (C), and switched power (D) relays are located near the battery. Inspect the relays in the same manner. Remove the relay to be tested. Set the multimeter to read ohms of resistance (Ω). 15-29...
  • Page 913 15.Electrical System MXU 550i Check for continuity between the switch terminals of the relay. In the case of the fuel pump relay these are the terminals that match up with the red/blue and orange/red wires. Jump a 12 V battery to the coil terminals of the relay. There should be continuity only when 12 V battery connected.

  • Page 914: Ignition System

    15.Electrical System MXU 550i Ignition System SAFETY FIRST: Protective gloves and eyewear are recommended at this point. The ignition timing is set at the factory and is not adjustable. To troubleshoot the ignition system, you will need a digital multimeter (Fluke model 73). Perform the following checks. Before performing any tests make sure the electrical connections are not loose or corroded.

  • Page 915: Troubleshooting

    15.Electrical System MXU 550i Troubleshooting See the troubleshooting chart on the Electrical Systems General Information topic. Spark Check Warning: Do not touch the spark plug or spark plug wire while cranking or running the engine as this can result in a severe shock. Remove these components Component Topic...

  • Page 916: Ignition Coil

    15.Electrical System MXU 550i Turn the key as to start the engine and check that the plug will spark. If the plug does not spark go through the following procedures to find the problem. Ignition Coil Primary Resistance Remove the front fender. See the Front Fender topic for more information.

  • Page 917: Spark Plug Cap Resistance

    15.Electrical System MXU 550i Measure the resistance between the ignition coil terminals. Ignition Coil Resistance (primary) Less than 1 ohm (terminal to terminal) Spark Plug Cap Resistance Set the multimeter to read ohms of resistance (kΩ). Measure the resistance between each end of the spark plug cap. Spark Plug Cap 4000 - 6000 ohms Ignition Coil Peak Voltage...

  • Page 918: Removal

    15.Electrical System MXU 550i Have the spark plug grounded to the frame as with the spark check. With the primary leads still connected to the ignition coil, touch the peak voltage adapter meter leads to the ignition coil leads. Turn the ignition switch to ON, hold in one of the brake levers, and push the engine start button.
  • Page 919 15.Electrical System MXU 550i Unplug the connector from the ignition coil. Pull the spark plug cap off of the spark plug. Remove the two ignition coil mounting bolts. 15-36...

  • Page 920: Installation

    15.Electrical System MXU 550i Remove the ignition coil. Installation Fit the ignition coil into place. 15-37...

  • Page 921: Ignition Pulse Generator / Crank Position Sensor

    15.Electrical System MXU 550i Install the two ignition coil mounting bolts and tighten the bolts securely. Plug in the ignition coil lead connector. Fit the spark plug cap onto the spark plug. Install the front fender. See the Front Fender topic form more information.

  • Page 922: Peak Voltage

    15.Electrical System MXU 550i Unplug the 2-pin ignition pulse generator / crank position sensor connector. Set the multimeter to read ohms of resistance (Ω). Measure the resistance between the terminals of the ignition pulse generator connector. Crank Position Sensor Resistance 90-110 ohms (green/white to blue/yellow) To replace the crank position sensor see the Generator Cover topic.

  • Page 923: Ecu

    15.Electrical System MXU 550i Bring up the data analysis page 04. At idle the ignition advance should show as indicated below at idle with a closed throttle. Ignition timing 5° at idle rpm Use the diagnostic tool to confirm the ECU version. See the Diagnostic Tool topic for more information.
  • Page 924 15.Electrical System MXU 550i Unplug the ECU connector (See the removal section below). Set the multimeter to read DC voltage (DCV). 15-41...
  • Page 925 15.Electrical System MXU 550i 15-42...

  • Page 926: Removal

    15.Electrical System MXU 550i Connect the meter (+) probe to the B4(R/W) wire and the meter (-) probe to the M3(G/B) wire to measure the voltage. There should be 12 V. Removal Remove the right side cover. See the Side Covers topic for more information.
  • Page 927 15.Electrical System MXU 550i To remove the ECU bracket remove the two anti-tamper fasteners. Remove the four bolts to remove the ECU from the bracket. Check the back of the ECU for information. 15-44...

  • Page 928: Installation

    15.Electrical System MXU 550i Installation Install the ECU to the bracket and tighten the four bolts securely. Fit the bracket to the frame and install two new anti-tamper fasteners. Plug in the ECU connector. Rotate the clip and lock the connector to the ECU. 15-45...

  • Page 929: Lights

    15.Electrical System MXU 550i Lights SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Headlight Aim The headlights can be adjusted vertically and horizontally. The geometric center of the HIGH beam light zone is to be used for vertical and horizontal aiming. 1.

  • Page 930: Headlights

    15.Electrical System MXU 550i DOWN Headlights Bulb Replacement Pull back the rubber cover and unplug the headlight bulb connector. Unhook the bulb clip and replace the bulb as needed. Be sure to secure the bulb with the clip on installation. Return the rubber cover to its installed position when finished. 15-47...

  • Page 931: Removal

    15.Electrical System MXU 550i Removal Remove the front fender. See the Front Fender topic for more information. Remove the five screws. Remove the headlight from the front fender. 15-48...

  • Page 932: Installation

    15.Electrical System MXU 550i Installation Install the headlight assembly into the front fender. Install the five screws and tighten them securely. 15-49...

  • Page 933: Taillights

    15.Electrical System MXU 550i Taillights Removal Remove the rear fender. See the Rear Fender topic for more information. Free the taillight wires from the clamp with the inner screw. Remove the four taillight screws. Remove the taillight from the rear fender. The taillights are LED that must be replaced as a unit if they fail.

  • Page 934: Installation

    15.Electrical System MXU 550i Installation Fit the taillight unit into place. Install the four taillight screws and tighten them securely. Guide the wires through the clamp with the inner bolt. Install the rear fender. See the Rear Fender topic for more information. 15-51...

  • Page 935: Starter Motor

    15.Electrical System MXU 550i Starter Motor SAFETY FIRST: Protective gloves and eyewear are recommended at this point. Inspection Remove these components Component Topic Seat Seat Side covers Side Covers Mudguards Mudguards and Footrests Pull back the rubber cover from the starter motor terminal nut. Set the multimeter to read DC voltage (DCV).

  • Page 936: Removal

    15.Electrical System MXU 550i Removal Remove these components Component Topic Seat Seat Side covers Side Covers Mudguards Mudguards and Footrests CVT (700 only) CVT Removal Turn OFF the ignition switch. Pull back the rubber cover from the starter motor terminal. Loosen the starter motor terminal nut with a 10 mm socket and free the lead from the terminal.

  • Page 937: Installation

    15.Electrical System MXU 550i Remove the starter motor. Installation Make sure the starter motor O-ring is in good condition. Apply fresh engine oil to the O-ring. 15-54...
  • Page 938 15.Electrical System MXU 550i Fit the starter motor into place on the top of the crankcases. The output end of the starter motor must engage with the starter reduction gear. Install the ground lead with the starter motor mounting bolt as shown. Tighten the starter motor mounting bolts to specification with an 8 mm socket.
  • Page 939 15.Electrical System MXU 550i Connect the lead to the starter motor. Tighten the nut securely with a 10 mm socket. Move the rubber cover into place over the terminal. Install these components Component Topic CVT (700 only) CVT Installation Mudguards Mudguards and Footrests Side covers Side Covers...

  • Page 940: Starting System

    15.Electrical System MXU 550i Starting System SAFETY FIRST: Protective gloves and eyewear are recommended at this point. You will need a digital multimeter (Fluke model 73) to inspect the starting system. System Diagram TROUBLESHOOTING Starter motor will not turn • Fuse burned out •...

  • Page 941: Starter Motor

    15.Electrical System MXU 550i Lack of power • Weak battery • Loosed wire or connection • Foreign matter stuck in starter motor Starter motor rotates but engine does not start • Faulty starter pinion • Starter motor rotates in reverse •...

  • Page 942: Fuse

    15.Electrical System MXU 550i Winch Leads (optional) Battery Relays (see below) Starter Relay Fuse Box Turn the ignition switch to the ON position. Make sure the engine kill switch is in the RUN position and the transmission is in neutral. Press the button to start the engine and listen for the starter relay to click.

  • Page 943: Voltage Inspection

    15.Electrical System MXU 550i Remove the fuse (30A). Replace the fuse if it is blown. Voltage Inspection Set the multimeter to read DC voltage (DCV). Check the voltage with the starter relay connector plugged in. Measure the voltage between the yellow/red wire and a ground. There should only be voltage with the gear position switch in neutral and the key is turned to start the engine or the brake pedal is pushed in and the key is turned to start the engine.

  • Page 944: Continuity Inspection

    15.Electrical System MXU 550i Continuity Inspection Remove the starter relay. Connect a fully charged 12 V battery positive wire to the relay switch Yellow/Red wire terminal and negative wire to the Yellow/Green wire terminal. There should be continuity between the cable terminals while the battery is connected, and no continuity when the battery is disconnected.

  • Page 945: Installation

    15.Electrical System MXU 550i Remove the starter relay from its holder in the rear fender. Unplug the connector from the starter relay. Remove the positive battery lead and starter motor lead nuts with a 10 mm socket. Free the positive battery and starter motor leads from the terminals. Installation Connect the starter motor lead to the terminal marked M.
  • Page 946 15.Electrical System MXU 550i Plug in the starter relay connector. 15-63...

  • Page 947: Switches

    15.Electrical System MXU 550i Switches SAFETY FIRST: Protective gloves and eyewear are recommended at this point. To test these switches, you will need a digital multimeter set to Ω (Ohms of resistance). If a switch does not meet specification replace it. Check the wiring diagrams for the continuity diagrams for the specific model being tested.

  • Page 948: Left Handlebar Switches

    15.Electrical System MXU 550i Check for continuity on the switch side of the connector. With the switch in the ON position there should be continuity between the orange and red wires. Turn the switch to the LIGHTS position. There should still be continuity between the orange and red wires, but there should also be continuity between the red and gray wires.

  • Page 949: Light Switch

    15.Electrical System MXU 550i Light Switch Check the dimmer switch for continuity as indicated. Engine Start Switch Check the engine start switch for continuity as indicated. 15-66...

  • Page 950: Engine Kill Switch

    15.Electrical System MXU 550i Engine Kill Switch Check the engine stop switch for continuity as indicated. Gear Position Switch Remove the right side cover. See the Side Covers topic for more information. Trace the wires up from the gear position switch. Unplug the gear position switch connector.

  • Page 951: Speed Sensor

    15.Electrical System MXU 550i Check for continuity between the switch wire terminals and a ground (G) as indicated. Neutral - Green Reverse - Black Low - Pink High - Brown To replace the gear position switch see the Crankcase topic. Speed Sensor The speed sensor is located on the back of the crankcase.

  • Page 952: Replacement

    15.Electrical System MXU 550i Inspect the speed sensor connector. Make sure the connector is making good contact with the sensor. If the speed sensor looks good but the speedometer doesn't function replace the speedometer with a known good unit. If the known good speedometer fails to function replace the speed sensor. Replacement Unplug the connector from the speed sensor.

  • Page 953: 2Wd/4Wd Actuator And Switch

    15.Electrical System MXU 550i Remove the speed sensor. Inspect the speed sensor O-ring and replace it as needed. Install the speed sensor. 2WD/4WD Actuator and Switch 2WD/4WD Switch Resistance Remove the front fender. See the Front Fender topic for more information. 15-70...
  • Page 954 15.Electrical System MXU 550i Unplug the 2WD/4WD shifting motor connector. Check for continuity as indicated. Note: If the meter does not show as specified, replace the front drive selector switch. Voltage The battery must be connected to test the 2WD/4WD switch voltage. See the Battery topic for more information.

  • Page 955: 2Wd/4Wd Actuator Inspection

    15.Electrical System MXU 550i 2WD/4WD Actuator Inspection NOTE: With the engine stopped and the ignition switch in the ON position, a momentary "whirring" sound must be noticeable each time the selector switch is moved to 2WD and 4WD. Test the switch, 30 amp fuse, and wiring connections prior to testing the actuator. Set the multimeter to read DC voltage (DCV).

  • Page 956: Brake Light Switches

    15.Electrical System MXU 550i 6. Connect the red tester lead to the brown/blue wire in the supply harness. The meter must show 12 DC volts. To remove the actuator see the Differential Disassembly topic. Brake Light Switches Test the front and rear brake light switches in the same manner. Use a digital multimeter to check for continuity.

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