KYMCO MXU 300 User Manual
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KYMCO MXU 300 User Manual

Atv mxu 300; mxu 250
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By KWANG YANG Motor Co., Ltd.
First Edition, Apr 2005
All rights reserved. Any reproduction or
unauthorized use without the written permission of
KWANG YANG Motor Co., Ltd.
is expressly prohibited.
4121-LCA5/LDE9-S00

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  • Page 1 By KWANG YANG Motor Co., Ltd. First Edition, Apr 2005 All rights reserved. Any reproduction or unauthorized use without the written permission of KWANG YANG Motor Co., Ltd. is expressly prohibited. 4121-LCA5/LDE9-S00...

  • Page 2: Table Of Contents

    PREFACE TABLE OF CONTENTS This Service Manual describes the GENERAL INFORMATION technical features and servicing FRAME COVERS/EXHAUST MUFFLER procedures for the KYMCO MXU INSPECTION/ADJUSTMENT 300/250. LUBRICATION SYSTEM Section 1 contains the precautions for FUEL SYSTEM all operations stated in this manual.

  • Page 3: General Information

    . GENERAL INFORMATION MXU 300/250 __________________________________________________________________________________ GENERAL INFORMATION SERIAL NUMBER---------------------------------------------------------- 1- 1 SPECIFICATIONS ---------------------------------------------------------- 1- 2 SERVICE PRECAUTIONS ------------------------------------------------ 1- 4 TORQUE VALUES --------------------------------------------------------- 1-12 SPECIAL TOOLS ----------------------------------------------------------- 1-14 LUBRICATION POINTS -------------------------------------------------- 1-15 CABLE & HARNESS ROUTING ---------------------------------------- 1-18 WIRING DIAGRAM (OFF ROAD) -------------------------------------- 1-22...

  • Page 4: Serial Number

    . GENERAL INFORMATION MXU 300/ 250 SERIAL NUMBER (1) Location of Frame Serial Number (2) Location of Engine Serial Number...

  • Page 5: Specifications

    . GENERAL INFORMATION MXU 300/250 SPECIFICATIONS (MXU 250) Air cleaner type & No Wet type element Model No. LB50 12.5 L (2.63 lmp Name & Type MXU 250 Fuel capacity gal, 3.25 US gal Overall length 1810 mm (72.4 in)
  • Page 6 . GENERAL INFORMATION MXU 300/ 250 SPECIFICATIONS (MXU 300) Model No. LA60 Air cleaner type & No Wet type element Name & Type MXU 300 12.5 L (2.63 lmp gal, Fuel capacity 3.25 US gal Overall length 1810 mm (72.4 in)

  • Page 7: Service Precautions

    . GENERAL INFORMATION MXU 300/250 SERVICE PRECAUTIONS Make sure to install new gaskets, O-rings, circlips, cotter pins, etc. when reassembling. When tightening bolts or nuts, begin with larger-diameter to smaller ones at several times, and tighten to the specified torque diagonally.
  • Page 8 . GENERAL INFORMATION MXU 300/ 250 Apply or add designated greases and lubricants to the specified lubrication points. After reassembly, check all parts for proper tightening and operation. When two persons work together, pay attention to the mutual working safety.
  • Page 9 . GENERAL INFORMATION MXU 300/250 If the fuse is burned out, find the cause and Confirm repair it. Replace it with a new one Capacity according to the specified capacity. After operation, terminal caps shall be installed securely. When taking out the connector, the lock on the connector shall be released before operation.
  • Page 10 . GENERAL INFORMATION MXU 300/ 250 The connector shall be inserted completely. If the double connector has a lock, lock it Snapping! at the correct position. Check if there is any loose wire. Before connecting a terminal, check for damaged terminal cover or loose negative terminal.
  • Page 11 . GENERAL INFORMATION MXU 300/250 After clamping, check each wire to make sure it is secure. 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.
  • Page 12 . GENERAL INFORMATION MXU 300/ 250 Route harnesses so they are neither pulled tight nor have excessive slack. Do not pull too tight! Protect wires and harnesses with electrical tape or tube if they contact a sharp edge or corner.
  • Page 13 . GENERAL INFORMATION MXU 300/250 After routing, check that the wire harnesses are not twisted or kinked. 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.
  • Page 14 . GENERAL INFORMATION MXU 300/ 250 Symbols: The following symbols represent the servicing methods and cautions included in this service manual. : Apply engine oil to the specified points. (Use designated engine oil for lubrication.) Engine Oil : Apply grease for lubrication.

  • Page 15: Torque Values

    Head CYL stud bolt (IN pipe) 0.9 (9, 6.5) Head CYL stud bolt (EX pipe) 0.9 (9, 6.5) A.C.G Startor 0.9 (9, 6.5) Drive bevel gear nut (MXU 300) 10 (100, 72) Driven bevel gear nut (MXU 300) 10 (100, 72) 1-12...
  • Page 16 4 (40, 29) Right pivot bolt (MXU 300) 11.8 (118, 85) Left pivot bolt (MXU 300) 1.1 (11, 8) Left pivot lock nut (MXU 300) 11.8 (118, 85) Final gear case mounting bolt 5.5 (55, 40) Axle hub holding bolt (MXU 250)

  • Page 17: Special Tools

    E034 Driven pulley disassembly Bearing puller E037 Nut wrench (MXU 300) F013 Left pivot lock nut removal/installation Pinion puller set (MXU 300) F014 Pinion/Bearing removal Lock nut wrench (MXU 300) F015 Pinion bearing nut removal Nut wrench (MXU 250) F010...

  • Page 18: Lubrication Points

    . GENERAL INFORMATION MXU 300/ 250 LUBRICATION POINTS ENGINE Lubrication Points Lubricant •Genuine KYMCO Engine Oil (SAE10W-30) Valve guide/valve stem movable part •API SG Engine Oil Cam lobes Valve rocker arm friction surface Cam chain Cylinder lock bolt and nut...
  • Page 19 . GENERAL INFORMATION MXU 300/250 FRAME The following is the lubrication points for the frame. Use general purpose grease for parts not listed. Apply clean engine oil or grease to cables and movable parts not specified. This will avoid abnormal noise and rise the durability of the ATV.
  • Page 20 . GENERAL INFORMATION MXU 300/ 250 Rear Swing Arm Axle Sprocket hub/Rear Axle Hub Collar/Oil Seal/Bearing Driven Sprocket 1-17...

  • Page 21: Cable & Harness Routing

    . GENERAL INFORMATION MXU 300/250 CABLE & HARNESS ROUTING Multi-function Connector Throttle Cable Handlebar Switch Wire Stop Switch Cord Rear Brake Fluid Hose Front Brake Fluid Hose Speed Cable Thermostatic Sensor Wire Harness Wire Ignition Switch Connector Motor Fan Wire/...
  • Page 22 . GENERAL INFORMATION MXU 300/ 250 Main Wire Harness Turn Signal Light/Stop Light Connectors (ON ROAD) REG.REC A.C.G Connector A.C.G Wire Coolant Reservoir Breather Hose Gear Change Temperature Sensor Wire Switch Wire License Light Turn Signal Relay Connector Ground Wire...
  • Page 23 . GENERAL INFORMATION MXU 300/250 Ignition Coil Rear Brake Fluid Hose Crankcase Breather Hose Harness Wire Start Motor Cable Handlebar Switch Wire Battery Cable Blow By Hose Motor Fan Wire Left Turn Signal Light (ON Throttle Cable Rear Brake Fluid Hose...
  • Page 24 . GENERAL INFORMATION MXU 300/ 250 Gear Change Control Unit Ignition Control Module Fuse Box Starter Relay Positive Terminal Cable Ground Wire Battery Starter Motor Cable Negative Terminal Cable 1-21...
  • Page 25 . GENERAL INFORMATION MXU 300/250 WIRING DIAGRAM ( MXU 250 OFF ROAD) 1-22...
  • Page 26 . GENERAL INFORMATION MXU 300/ 250 WIRING DIAGRAM (MXU 250 ON ROAD) 1-23...
  • Page 27 . GENERAL INFORMATION MXU 300/250 WIRING DIAGRAM (MXU 300 OFF ROAD) 1-24...
  • Page 28 . GENERAL INFORMATION MXU 300/ 250 WIRING DIAGRAM (MXU 300 ON ROAD) 1-25...

  • Page 29: Troubleshooting

    . GENERAL INFORMATION MXU 300/250 TROUBLESHOOTING ENGINE WILL NOT START OR IS HARD TO START Inspection/Adjustment Probable Cause Symptom Check if fuel reaches carburetor by loosening drain screw Empty fuel tank Clogged fuel line between fuel tank and carburetor Clogged float oil passage...
  • Page 30 . GENERAL INFORMATION MXU 300/ 250 ENGINE LACKS POWER Inspection/Adjustment Probable Cause Symptom Start engine and accelerate lightly for observation Clogged air cleaner Restricted fuel flow Engine speed Engine speed does not Clogged fuel tank cap breather hole increase sufficiently...
  • Page 31 . GENERAL INFORMATION MXU 300/250 POOR PERFORMANCE (ESPECIALLY AT IDLE AND LOW SPEEDS) Inspection/Adjustment Symptom Probable Cause Check ignition timing Faulty ignition unit Incorrect timing Correct timing Faulty pulser coil Check carburetor air screw adjustment Mixture too rich (turn screw...
  • Page 32 . GENERAL INFORMATION MXU 300/ 250 POOR PERFORMANCE (AT HIGH SPEED) Inspection/Adjustment Symptom Probable Cause Check ignition timing Faulty ignition unit Correct timing Incorrect timing Faulty pulser coil Check valve clearance Improperly adjusted valve Correctly adjusted Incorrectly adjusted clearance Worn valve seat...
  • Page 33 . GENERAL INFORMATION MXU 300/250 POOR CHARGING (BATTERY OVER DISCHARGING OR OVERCHARGING) Undercharging Inspection/Adjustment Symptom Probable Cause Start engine and test limit voltage of battery terminals Dead battery Voltage does not Normal voltage increase Faulty battery Measure resistance between AC generator coil terminals Faulty A.C.
  • Page 34 . GENERAL INFORMATION MXU 300/ 250 NO SPARK AT SPARK PLUG Inspection/Adjustment Symptom Probable Cause Replace with a new spark plug and inspect again Good spark Weak or no spark Faulty spark plug Check spark plug cap and high-tension wire...

  • Page 35: Frame Covers/Exhaust Muffler

    . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 __________________________________________________________________________________ FRAME COVERS/EXHAUST MUFFLER SERVICE INFORMATION------------------------------------------------ 2- 2 TROUBLESHOOTING----------------------------------------------------- 2- 2 FRAME COVERS ----------------------------------------------------------- 2- 3 EXHAUST MUFFLER ----------------------------------------------------- 2-11...
  • Page 36 . FRAME COVERS/EXHAUST MUFFLER MXU 300/250...

  • Page 37: Frame Covers/Exhaust Muffler

    . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • When removing frame covers, use special care not to pull them by force because the cover joint claws may be damaged. • Make sure to route cables and harnesses according to the Cable & Harness Routing.

  • Page 38: Frame Covers

    . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 FRAME COVERS SEAT REMOVAL Pull the lever right and pull up the seat at the rear. Remove the seat. Lever Seat INSTALLATION To install the seat, align the tabs on the seat with the grommets on the frame and press the seat down until it locks.
  • Page 39 . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 Remove the two mounting bolts from the front cargo rack right/left side under the front fender, remove the front cargo rack. Installation is in the reverse order of removal. Mounting Bolts Right Signal Light Connectors...
  • Page 40 . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 Bolts REAR CARGO RACK REMOVAL/INSTALLATION Remove the two mounting bolts from the rear cargo rack. Remove the two bolts under the rear fender. Mounting Bolts Mounting Bolts Remove the two mounting bolts from the rear cargo rack right/left side under the rear fender.
  • Page 41 . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 Screws/Nuts Remove 6 screws/nuts, 4 mounting bolts and the right footboard. During removal, do not pull the joint claws forcedly to avoid damage. Installation is in the reverse order of removal. Mounting Bolts Bolts...
  • Page 42 . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 FRONT CENTER COVER REMOVAL/INSTALLATION Remove the front cargo rack (see page 2-3). Remove the two screws and front center cover. During removal, do not pull the joint claws forcedly to avoid damage. Installation is in the reverse order of removal.
  • Page 43 . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 Fuel Tank Cap/Fuel Tank Seal FUEL TANK COVER REMOVAL/INSTALLATION Remove the front center cover (see page 2- Remove the four screws from the fuel tank cover. Remove the fuel tank cap by turning it counterclockwise and fuel tank seal, then remove the fuel tank cover.
  • Page 44 . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 Screws Remove the two screws and front fender. Installation is in the reverse order of removal. REAR FENDER REMOVAL/INSTALLATION Remove rear cargo rack (see page 2-5), battery (see chapter 16) and right/left side cover.
  • Page 45 . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 Bolts Remove the five bolts from the rear fender. Bolts Remove the two bolts under the rear fender right/left side. Loosen the air outlet hose band screw and disconnect the air outlet hose from the V- belt compartment cover, then remove the rear fender.

  • Page 46: Exhaust Muffler

    . FRAME COVERS/EXHAUST MUFFLER MXU 300/250 EXHAUST MUFFLER REMOVAL/INSTALLATION Remove the exhaust pipe joint nuts. Joint Nuts Bolt Remove the muffler mounting bolt, nut and exhaust muffler. Inspect the gasket. If the exhaust gas leaks, the gasket should be replaced.

  • Page 47: Inspection/Adjustment

    CARBURETOR IDLE SPEED/IGNITION TIMING ------------------ 3- 9 CYLINDER COMPRESSION/ ENGINE OIL--------------------------- 3-10 TRANSMISSION OIL REPLACEMENT ------------------------------- 3-12 REAR FINAL GEAR CASE OIL REPLACEMENT (MXU 300) ---- 3-14 DRIVE BELT/BRAKE PADS INSPECTION --------------------------- 3-15 BRAKE FLUID INSPECTION/ HEADLIGHT AIM------------------- 3-16 STEERING SYSTEM INSPECTION------------------------------------- 3-17...

  • Page 48: Service Information

    At disassembly : 600 cc (0.52 lmp qt, 0.64 Us qt) At change : 500 cc (0.43 lmp qt, 0.53 Us qt) Rear final gear case oil (MXU 300) At disassembly : 150 cc (5.33 lmp oz, 5 Us oz) At change : 100 cc (3.56 lmp qt, 3.33 Us qt)
  • Page 49 . INSPECTION/ADJUSTMENT MXU 300/250 Ignition timing : BTDC 5°±1°/2000 rpm Tire pressure 1 Rider Front 0.28 kgf/cm² (28 Kpa, 3.2 psi) Rear 0.28 kgf/cm² (28 Kpa, 3.2 psi) Tire size: Front : 22*7-10 Rear : 22*10-10 TORQUE VALUES Front wheel nut 4.5 kgf-m (45 Nm, 32 lbf-ft)

  • Page 50: Maintenance Schedule

    . INSPECTION/ADJUSTMENT MXU 300/250 MAINTENANCE SCHEDULE 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. The need for costly overhaul work will be greatly reduced.

  • Page 51: Fuel Line/Throttle Operation/Air Cleaner

    . INSPECTION/ADJUSTMENT MXU 300/250 Fuel Filter FUEL LINE Check the fuel tubes and replace any parts, which show signs of deterioration, damage or leakage. Do not smoke or allow flames or sparks in your working area. Fuel tubes Lock nut...
  • Page 52 . INSPECTION/ADJUSTMENT MXU 300/250 Unscrew (3) the clamp (5) and remove the air cleaner assembly (4) from the air cleaner housing. Remove the screw and remove the air Screw Air Cleaner Holder cleaner assembly from the air cleaner holder. Air Cleaner Remove the air cleaner and air cleaner screen from the air cleaner body.

  • Page 53: Air Filter For Drive Belt

    . INSPECTION/ADJUSTMENT MXU 300/250 CLEAN AIR FILTER ELEMENT Wash the element gently, but throughly in solvent. Use parts cleaning solvent only. Never use gasoline or low flash point solvents which may lead to a fire or explosion. Squeeze the excess solvent out of the element and let dry.

  • Page 54: Secondary Aur Supply System/Spark Plug

    . INSPECTION/ADJUSTMENT MXU 300/250 Vacuum Hose AICV Control solenoid Valve SECONDARY AIR SUPPLY SYSTEM This model is equipped with a built-in secondary air supply system. The pulse secondary air supply system is located on the cylinder head cover. The secondary air supply system introduces filtered air into exhaust gases in the exhaust port.

  • Page 55: Valve Clearance

    . INSPECTION/ADJUSTMENT MXU 300/250 Gap, Wear, and Fouling Deposits Measure the spark plug gap. Spark Plug Gap: 0.6～0.7 mm (0.002～ 0.003 in) When installing, first screw in the spark plug by hand and then tighten it with a spark plug wrench.

  • Page 56: Carburetor Idle Speed/Ignition Timing

    Start the engine and connect a tachometer. Turn the throttle stop screw to obtain the specified idle speed. Idle Speed: MXU 250: 1500±100 rpm MXU 300: 1600±100 rpm Air Screw Throttle Stop Screw When the engine misses or run erratic, adjust the air screw.

  • Page 57: Cylinder Compression/ Engine Oil

    Open the throttle valve fully and push the starter button to test the compression. Cylinder compression: MXU 250: 15 kg/cm² (1500 kPa, 213 psi) MXU 300: 16 kg/cm² (1600 kPa, 227 psi) If the compression is low, check for the following: - Leaky valves...
  • Page 58 . INSPECTION/ADJUSTMENT MXU 300/250 Oil Fill Cap ENGINE OIL REPLACEMENT Place the machine on a level place. Warm up the engine for several minutes and stop it. Place a container under the engine. Remove the oil fill cap and drain plug to drain the oil.

  • Page 59: Transmission Oil Replacement

    . INSPECTION/ADJUSTMENT MXU 300/250 O-ring Compression Spring Clean the oil strainer with solvent. Inspect the O-ring and replace if damaged. Reinstall the O-ring, oil strainer, compression spring and oil filter cap. Tighten the oil filter cap to specification. Torque: 1.5 kgf-m (15 Nm, 11 lbf-ft) Fill the engine with oil and install the oil fill cap.
  • Page 60 At disassembly : 400 cc (0.35 lmp qt, 0.42 Us qt) At change : 300 cc (0.26 lmp qt, 0.32 Us qt) Oil Capacity (MXU 300): At disassembly : 600 cc (0.52 lmp qt, 0.64 Us qt) At change : 500 cc (0.43 lmp qt, 0.53 Us qt)

  • Page 61: Rear Final Gear Case Oil Replacement (Mxu 300)

    Torque: 2 kgf-m (20 Nm, 15 lbf-ft) Fill the gear case with the recommended oil (SAE #90). Oil Capacity (MXU 300): At disassembly : 0.15 L (5.33 lmp oz, 5 US oz) At change : 0.1 L (3.56 lmp oz, 3.33 US oz)

  • Page 62: Drive Belt/Brake Pads Inspection

    . INSPECTION/ADJUSTMENT MXU 300/250 Drive Belt DRIVE BELT Remove the left crankcase cover. Inspect the drive belt for cracks, scaling, chipping or excessive wear. Measure the V-belt width Service limit: 22 mm (0.88in) Replace the drive belt if out of specification.

  • Page 63: Brake Fluid Inspection/ Headlight Aim

    . INSPECTION/ADJUSTMENT MXU 300/250 BRAKE FLUID INSPECTION Inspection Window (R/L Brake Lever) Check if the fluid level is below the lower level mark through the inspection window. Inspection Window (Rear Brake Pedal) Adjust Screws HEADLIGHT AIM Turn the ignition switch ON and start the engine.

  • Page 64: Steering System Inspection

    . INSPECTION/ADJUSTMENT MXU 300/250 STEERING SYSTEM INSPECTION 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 65: Toe-In Adjustment

    . INSPECTION/ADJUSTMENT MXU 300/250 TOE-IN ADJUSTMENT Place the machine on a level place. Measure the toe-in Adjust if out of specification. Toe-in measurement steps: Mark both front tire tread centers. Raise the front end of the machine so that there is no weight on the front tires.

  • Page 66: Wheels/Tires

    . INSPECTION/ADJUSTMENT MXU 300/250 Tie-rod End Nuts • Be sure that both tie-rod are turned the same amount. If not, the machine will drift tight or left even though the handlebar is positioned straight which may lead to mishandling and accident.
  • Page 67 . INSPECTION/ADJUSTMENT MXU 300/250 Rear Axle Nut Check the rear axle nut for looseness. If the axle nuts are loose, tighten them to the specified torque. Torque: Front : 7 kgf-m (70 Nm, 50 lbf-ft) Rear : 10 kgf-m (100 Nm, 72 lbf-ft) Inspect the tire surfaces.

  • Page 68: Drive Chain Slack Adjustment (Mxu 250)

    . INSPECTION/ADJUSTMENT MXU 300/250 DRIVE CHAIN SLACK ADJUSTMENT (MXU 250) Before checking and/or adjusting, rotate the rear wheels several revolutions and check slack at several points to find the tightest point. Check and/or adjust the chain slack with the rear wheels in this “tightest”...
  • Page 69 . INSPECTION/ADJUSTMENT MXU 300/250 To tighten the chain, push the ATV forward. To loosen the chain, pull the ATV backward. Bolts Retighten the two axle hub holder bolt and caliper holder bolt to the specification. Torque: Axle hub holding bolt:...

  • Page 70: Drive Select Lever Adjustment

    . INSPECTION/ADJUSTMENT MXU 300/250 Standard/Phillips Screwdriver DRIVE SELECT LEVER ADJUSTMENT Turn the ignition switch is ON and make sure the engine stop switch in the OFF position. Loosen the lock nuts of rod. Shift the gear to neutral by moving the shift lever and/or turn the rod.

  • Page 71: Cable Inspection And Lubrication

    . INSPECTION/ADJUSTMENT MXU 300/250 CABLE INSPECTION AND LUBRICATION Damaged cable sheath may cause corrosion and interfere with the cable movement. An unsafe condition may result so replace such cable as soon as possible. Inspect the cable sheath. Replace if damage.

  • Page 72: Cooling System

    . INSPECTION/ADJUSTMENT MXU 300/250 Maximum Mark Minimum Mark COOLING SYSTEM COOLANT LEVEL INSPECTION Place the machine on the level ground. Check the coolant level in the coolant reservoir when the engine is cold as the coolant level will vary with engine temperature.

  • Page 73: Spark Arrester Cleaning (Off Road)

    . INSPECTION/ADJUSTMENT MXU 300/250 SPARK ARRESTER CLEANING (OFF ROAD) Be sure the exhaust pipe and muffler are cool before cleaning the spark arrester. 1. Remove the bolt (1). 2. Remove the tailpipe (2) by pulling it out of the muffler.

  • Page 74: Lubrication System

    . LUBRICATION SYSTEM MXU 300/250 __________________________________________________________________________________ LUBRICATION SYSTEM SERVICE INFORMATION------------------------------------------------ 4- 2 TROUBLESHOOTING----------------------------------------------------- 4- 2 ENGINE OIL/OIL FILTER ------------------------------------------------ 4- 3 OIL PUMP -------------------------------------------------------------------- 4- 3...
  • Page 75 . LUBRICATION SYSTEM MXU 300/250 LUBRICATION SYSTEM Rocker Arm Shaft Crankshaft Oil Filter Screen Oil Pump...

  • Page 76: Lubrication System

    . LUBRICATION SYSTEM MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • 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 and oil line.

  • Page 77: Engine Oil/Oil Filter

    . LUBRICATION SYSTEM MXU 300/250 ENGINE OIL/OIL FILTER OIL LEVEL AND OIL CHANGE Refer to the “ENGINE OIL” section in the chapter 3 to check the oil level and replacement and oil filter cleaning. OIL PUMP REMOVAL Remove the right crankcase cover and the A.C.
  • Page 78 . LUBRICATION SYSTEM MXU 300/250 Oil Pump Driven Sprocket Remove the oil pump drive chain and oil driven sprocket. Oil Pump Drive Chain Remove the two oil pump bolts for remove the oil pump. Oil Pump Bolts Screw OIL PUMP DISASSEMBLY Remove the screw and disassemble the oil pump.
  • Page 79 . LUBRICATION SYSTEM MXU 300/250 Inner Rotor Measure the inner rotor-to-outer rotor clearance. Service Limit: 0.2 mm (0.008 in) Outer Rotor Outer Rotor Measure the pump body-to-outer rotor clearance. Service Limit: 0.25 mm (0.01 in) Pump Body Pump Cover Outer Rotor...
  • Page 80 . LUBRICATION SYSTEM MXU 300/250 Pump Shaft Make sure that the pump shaft rotates freely without binding. Install oil pump driven sprocket and drive chain, circlip and oil separator cover.

  • Page 81: Fuel System

    . FUEL SYSTEM MXU 300/250 __________________________________________________________________________________ FUEL SYSTEM SERVICE INFORMATION------------------------------------------------ 5- 2 TROUBLESHOOTING----------------------------------------------------- 5- 3 FUEL TANK ----------------------------------------------------------------- 5- 4 FUEL VALVE --------------------------------------------------------------- 5- 4 THROTTLE VALVE---------------------------------------------------------- 5- 7 CARBURETOR-------------------------------------------------------------- 5- 9 AIR CLEANER HOUSING ------------------------------------------------ 5-15 PAIR SOLENOID VALVE ------------------------------------------------ 5-16...
  • Page 82 . FUEL SYSTEM MXU 300/250...

  • Page 83: Fuel System

    . FUEL SYSTEM MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS Gasoline is very dangerous. When working with gasoline, keep sparks and flames away from the working area. Gasoline is extremely flammable and is explosive under certain conditions. Be sure to work in a well-ventilated area.

  • Page 84: Troubleshooting

    . FUEL SYSTEM MXU 300/250 TROUBLESHOOTING Engine cranks but won’t start Engine lacks power • No fuel in tank • Clogged air cleaner • No fuel to carburetor • Faulty carburetor • Cylinder flooded with fuel • Faulty ignition system •...

  • Page 85: Fuel Tank

    . FUEL SYSTEM MXU 300/250 Fuel Tube Fuel Valve FUEL TANK REMOVAL Warning • Keep sparks and flames away from the work area. • Wipe off any spilled gasoline. Remove the seat (See page 2-3), right and left side frame cover (See page 2-6) and fuel tank cover (See page 2-8).
  • Page 86 . FUEL SYSTEM MXU 300/250 Control Shaft Screws Washer DISASSEMBLY Remove the two screws on the retaining ring and then remove retaining ring. Remove the washer and control shaft. Retaining Ring Fuel Valve Body Rubber Gasket Remove the rubber gasket from the fuel valve body.
  • Page 87 . FUEL SYSTEM MXU 300/250 ASSEMBLY Reverse the “DISASSEMBLY” procedures. Install rubber gasket, control shaft, washer and retaining ring. • Aligning the tab on the control shaft with the outlet duct in the fuel valve body. • Aligning the tab on the retaining ring with the outlet duct in the fuel valve body.

  • Page 88: Throttle Valve

    . FUEL SYSTEM MXU 300/250 Carburetor Cap THROTTLE VALVE DISASSEMBLY Remove the fuel tank. (Refer to “FUEL TANK” section in the chapter 5) Remove the carburetor cap. Throttle Valve Pull out the throttle valve. Compress the spring to disconnect the throttle cable by hand.
  • Page 89 . FUEL SYSTEM MXU 300/250 Spring Remove the spring from the throttle valve Needle Retainer Throttle Valve Pry off the needle retainer and remove the jet needle. Check the throttle valve and jet needle for wear or damage. ASSEMBLY Reverse the “DISASSEMBLY” procedures.

  • Page 90: Carburetor

    . FUEL SYSTEM MXU 300/250 CARBURETOR REMOVAL Remove the fuel tank and carburetor cap. (Refer to “FUEL TANK” and “THROTTLE VALVE DISASSEMBLY” section in the chapter 5) Loosen the drain screw to drain the gasoline from the float chamber. • Keep sparks and flames away from the work area.
  • Page 91 . FUEL SYSTEM MXU 300/250 O-ring Check the O-ring for damage. Replace with new ones if necessary. Float Chamber DISASSEMBLY Remove the float chamber attaching three screws and remove the float chamber. Screws Remove the baffle plate. Baffle plate 5-10...
  • Page 92 . FUEL SYSTEM MXU 300/250 Float Pull out the float pin, then remove float and float valve. Inspect the float for deformation or damage. Float Pin Float Valve Slow Jet Throttle Stop Screw Remove the main jet, needle jet holder, and needle jet.
  • Page 93 . FUEL SYSTEM MXU 300/250 Slow Jet Needle Jet Needle Jet Holder Main Jet Remove the two screws and the air cut-off valve cover. Screws Spring Diaphragm Remove the spring, diaphragm and O-rings. Inspect the diaphragm and spring for wear or damage.
  • Page 94 . FUEL SYSTEM MXU 300/250 CARBURETOR CLEANING Blow compressed air through all passages of the carburetor body. Float Valve FLOAT/FLOAT VALVE INSPECTION Inspect the float valve seat for wear or damage. Inspect the float for damage or fuel level inside the float chamber.
  • Page 95 . FUEL SYSTEM MXU 300/250 ASSEMBLY Install the slow jet. Install the needle jet, needle jet holder and main jet. Install the throttle stop screw and air screw Install the spring, diaphragm and O-rings. • When installing the air screw, return it...

  • Page 96: Air Cleaner Housing

    . FUEL SYSTEM MXU 300/250 Breather Hose AIR CLEANER HOUSING REMOVAL/INSTALLATION Remove the seat (see page 2-3). Remove the side covers (see page 2-6). Remove the clip and disconnect the crankcase breather hose from the crankcase. Loosen the carburetor-to-air cleaner connecting tube band screw.

  • Page 97: Pair Solenoid Valve

    . FUEL SYSTEM MXU 300/250 Vacuum Hose PAIR SOLENOID VALVE REMOVAL/INSTALLATION Remove the two nuts and electrical holder. Disconnect air supply hose and vacuum hose from the air solenoid valve, then remove the air solenoid valve. Vacuum Hose PAIR Solenoid Valve...

  • Page 98: Engine Removal

    MXU 300/ 250 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ ENGINE REMOVAL __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 6- 1 ENGINE REMOVAL (MXU 250) ---------------------------------------- 6- 2 ENGINE INSTALLATION (MXU 250) --------------------------------- 6- 7 ENGINE REMOVAL (MXU 300) ---------------------------------------- 6- 8 ENGINE INSTALLATION (MXU 300) --------------------------------- 6-17...

  • Page 99: Engine Removal

    6. ENGINE REMOVAL/INSTALLATION MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • A floor jack or other adjustable support is required to support and maneuver the engine. Be careful not to damage the machine body, cables and wires during engine removal. • Use shop towels to protect the machine body during engine removal.
  • Page 100 . ENGINE REMOVAL MXU 300/ 250 Breather Hose Vacuum Hose ENGINE REMOVAL (MXU 250) Drain engine oil and transmission oil. (Refer to chapter 3). Remove frame covers and exhaust pipe. (Refer chapter 2). Remove the air cleaner housing and carburetor. (Refer to chapter 5).
  • Page 101 6. ENGINE REMOVAL/INSTALLATION MXU 300/250 Remove the drive select shift to drive select arm connecting bolt and nut. Remove the two mounting nuts and drive select shift. Nuts Bolt/Nut Speedometer Cable Disconnect the speedometer cable. Drive Sprocket Cover Bolts Remove the three bolts at the drive sprocket cover and then remove the drive sprocket cover.

  • Page 102: Engine Removal (Mxu 250)

    . ENGINE REMOVAL MXU 300/ 250 Rubber Sleeve Slide the rubber sleeve back to expose the starter motor wire nut. Remove the starter motor wire nut for disconnect the starter motor wire. Ground Wire Bolt Remove the bolt at the starter motor for disconnect the ground wire lead.
  • Page 103 6. ENGINE REMOVAL/INSTALLATION MXU 300/250 Inlet Hose Outlet Hose Loosen the inlet hose band screw and then disconnect the inlet hose from the left crankcase cover. Loosen the outlet hose band screw and then disconnect the outlet hose from the left crankcase cover.
  • Page 104 . ENGINE REMOVAL MXU 300/ 250 Remove the engine assembly to the left side of the machine.

  • Page 105: Engine Installation (Mxu 250)

    6. ENGINE REMOVAL/INSTALLATION MXU 300/250 ENGINE INSTALLATION (MXU 250) Installation is in the reverse order of removal. The rear upper and lower engine mounting bolts and nuts loosely install, then tighten the engine mounting nuts to the specified torque. Torque: 40 N-m (4 kgf-m, 29 lbf-ft)
  • Page 106 . ENGINE REMOVAL MXU 300/ 250 Bolts Connectors ENGINE REMOVAL (MXU 300) Drain engine oil and transmission oil. (Refer to chapter 3). Remove frame covers and exhaust pipe. (Refer chapter 2). Remove the air cleaner housing and carburetor. (Refer to chapter 5).
  • Page 107 6. ENGINE REMOVAL/INSTALLATION MXU 300/250 Drive Select Shift Remove the drive select shift to drive select arm connecting bolt and nut. Remove the two mounting nuts and drive select shift. Bolt Nuts Bolt Remove the bolt and thermostat. Thermostat Electrical Holder Vacuum Hose Remove the two nuts and electrical holder.

  • Page 108: Engine Removal (Mxu 300)

    . ENGINE REMOVAL MXU 300/ 250 Band Loosen the hose band and disconnect the water hose from the water pump. Water Hose Ignition Pulse Generator Connectors Remove the A.C. Generator, ignition pulse generator and gear change switch connectors. A.C. Generator...
  • Page 109 6. ENGINE REMOVAL/INSTALLATION MXU 300/250 Rubber Sleeve Slide the rubber sleeve back to expose the starter motor wire nut. Remove the starter motor wire nut for disconnect the starter motor wire. Inlet Hose Outlet Hose Loosen the inlet hose band screw and then disconnect the inlet hose from the left crankcase cover.
  • Page 110 . ENGINE REMOVAL MXU 300/ 250 Brackets Remove the four bolts for remove the left and right engine brackets. Bolts Remove the rear upper mounting bolt and nut. Bolt Remove the rear lower mounting bolt and nut. Bolt 6-12...
  • Page 111 6. ENGINE REMOVAL/INSTALLATION MXU 300/250 Screw (Only swingarm side) Joint Boot Loosen the joint boot band screw on the swingarm side. Remove the joint boot from the swingarm. Rise the engine front side and move the engine forward, then remove the engine...
  • Page 112 . ENGINE REMOVAL MXU 300/ 250 Turn the engine rear side to frame left side. Lower the cylinder head to turn the cylinder head to frame left side. 6-14...
  • Page 113 6. ENGINE REMOVAL/INSTALLATION MXU 300/250 Move the engine to a rubber mat. 6-15...
  • Page 114 . ENGINE REMOVAL MXU 300/ 250 Bolts Remove the two bolts and intake manifold may more easy to move engine. Intake Manifold Holder Plate Be careful not to damage choke knob cable and holder plate when the engine is moved.

  • Page 115: Engine Installation (Mxu 300)

    6. ENGINE REMOVAL/INSTALLATION MXU 300/250 Apply Grease ENGINE INSTALLATION (MXU 300) Installation is in the reverse order of removal. Check the joint boot for tears or other damage. Check the secondary driven bevel gear shaft splines and universal joint splines for wear or damage.
  • Page 116 . ENGINE REMOVAL MXU 300/ 250 The brackets, bolts, front engine mounting bolt and loosely install, then tighten the bolts on the brackets to the specified torque. Torque: 22 N-m (2.2 kgf-m, 16 lbf-ft) Tighten the front engine mounting bolt and nut to the specified torque.

  • Page 117: Cylinder Head/Valves

    . CYLINDER HEAD/VALVES MXU 300/250 __________________________________________________________________________________ CYLINDER HEAD/VALVES SERVICE INFORMATION------------------------------------------------ 7- 2 TROUBLESHOOTING----------------------------------------------------- 7- 3 CYLINDER HEAD COVER----------------------------------------------- 7- 4 CAMSHAFT/CAMSHAFT HOLDER------------------------------------ 7- 4 CYLINDER HEAD---------------------------------------------------------- 7-10...
  • Page 118 7. CYLINDER HEAD/VALVES MXU 300/250...

  • Page 119: Cylinder Head/Valves

    . CYLINDER HEAD/VALVES MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • The cylinder head can be serviced with the engine installed in the frame. • When assembling, apply molybdenum disulfide grease or engine oil to the valve guide movable parts, valve arm and camshaft sliding surfaces for initial lubrication.

  • Page 120: Troubleshooting

    7. CYLINDER HEAD/VALVES MXU 300/250 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 White smoke from exhaust muffler • Compression too low • Worn valve stem or valve guide •...

  • Page 121: Cylinder Head Cover

    . CYLINDER HEAD/VALVES MXU 300/250 Cylinder Head Cover Bolts CYLINDER HEAD COVER REMOVAL Remove fuel tank. (Refer to the chapter 5) Disconnect the crankcase breather hose and pair control valve hose from the cylinder head cover. (Refer to the chapter 6) Remove the four bolts at the cylinder head cover, then remove the cylinder head cover.
  • Page 122 7. CYLINDER HEAD/VALVES MXU 300/250 Tensioner Turn the cam chain tensioner screw clockwise to tighten it. Nuts/Washers Camshaft Holder Remove the four camshaft holder nuts and washers. Diagonally loosen the cylinder head nuts in 2 or 3 times. Remove the camshaft holder and dowel pins.
  • Page 123 . CYLINDER HEAD/VALVES MXU 300/250 Stop Plate Rocker Arms CAMSHAFT HOLDER DISASSEMBLY Take out the valve rocker arm shafts. Remove the valve rocker arms, arm shafts and stop plate. Rocker Arm Shafts Camshaft Holder CAMSHAFT HOLDER INSPECTION Inspect the camshaft holder for wear or damage.
  • Page 124 7. CYLINDER HEAD/VALVES MXU 300/250 Measure each rocker arm shaft O.D. Measure the I.D. of each valve rocker arm. Measure arm to shaft clearance. Replace as a set if out of specification. Service limits: 0.1 mm (0.004 in) Check the stop plate spring for damage.
  • Page 125 . CYLINDER HEAD/VALVES MXU 300/250 Camshaft Bearings CAMSHAFT INSPECTION Check each camshaft bearing for play or damage. Replace the camshaft assembly with a new one if the bearings are noisy or have excessive play. Inspect camshaft lobes for pitting/scratches/blue discoloration.
  • Page 126 7. CYLINDER HEAD/VALVES MXU 300/250 Install the camshaft dowel pins and holder. Install the washers and nuts and tighten the nuts. • Apply engine oil to the threads of the cylinder head nuts. • Diagonally tighten the cylinder head nuts in 2～3 times.

  • Page 127: Cylinder Head

    . CYLINDER HEAD/VALVES MXU 300/250 Intake Manifold CYLINDER HEAD REMOVE Remove the camshaft (page 7-4). Remove the carburetor. (Refer to the “carburetor remove” section in the chapter Remove the exhaust muffler (page 2-11). Remove the two bolts and then remove the carburetor intake manifold.
  • Page 128 7. CYLINDER HEAD/VALVES MXU 300/250 VALVE /VALVE GUIDE INSPECTION Inspect each valve for bending, burning, scratches or abnormal stem wear. If any defects are found, replace the valve with a new one. Check valve movement in the guide. Measure each valve stem O.D.
  • Page 129 . CYLINDER HEAD/VALVES MXU 300/250 Measure compressed force (valve spring) and installed length. Replace if out of specification. Standard: IN : 10.20～11.84kg(at 18.05mm) EX : 19.14～22.02kg(at 21.5mm) Measure the spring tilt. Replace if out of specification. Standard: IN : 0.8mm (0.032) EX : 1.07mm (0.0428)
  • Page 130 7. CYLINDER HEAD/VALVES MXU 300/250 ASSEMBLY Install the valve spring seats and oil seal. Be sure to install new oil seal. Lubricate each valve with engine oil and insert the valves into the valve guides. Install the valve springs and retainers.

  • Page 131: Cylinder/Piston

    . CYLINDER/PISTON MXU 300/250 __________________________________________________________________________________ CYLINDER /PISTON SERVICE INFORMATION------------------------------------------------ 8- 2 TROUBLESHOOTING----------------------------------------------------- 8- 2 CYLINDER/PISTON ------------------------------------------------------- 8- 4...
  • Page 132 . CYLINDER/PISTON MXU 300/250...
  • Page 133 . CYLINDER/PISTON MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • The cylinder and piston can be serviced with the engine installed in the frame. • After disassembly, clean the removed parts and dry them with compressed air before inspection. TROUBLESHOOTING • When hard starting or poor performance at low speed occurs, check the crankcase breather for white smoke.
  • Page 134 . CYLINDER/PISTON MXU 300/250 Unit: mm (in) SPECIFICATIONS Item Standard Service Limit 72.705～72.715 I.D. 72.8 (2.912) (2.9082～2.9086) ⎯ Warpage 0.05 (0.002) Cylinder ⎯ Cylindricity 0.05 (0.002) ⎯ True roundness 0.05 (0.002) 0.015～0.055 0.09 (0.0036) (0.0006～0.0022) Ring-to-groove clearance 0.015～0.055 Second 0.09 (0.0036) (0.0006～0.0022)
  • Page 135 . CYLINDER/PISTON MXU 300/250 Gasket CYLINDER/PISTON REMOVAL Remove the cylinder head. (Refer to the chapter 7) Remove the two dowel pins, cylinder head gasket and cam chain guide. Cam Chain Guide Dowel Pins Cylinder Screw Unscrew the clamp and disconnect the water hose.
  • Page 136 . CYLINDER/PISTON MXU 300/250 Remove the piston pin clip. Towel Piston Place a clean shop towel in the crankcase to keep the piston pin clip from falling into the crankcase. Press the piston pin out of the piston and remove the piston.
  • Page 137 . CYLINDER/PISTON MXU 300/250 Remove the piston rings and insert each piston ring into the cylinder bottom. Use the piston head to push each piston ring into the cylinder. Measure the piston ring end gap. Service Limit (replace if over): Top: 0.5 mm (0.02 in)
  • Page 138 . CYLINDER/PISTON MXU 300/250 Measure the piston O.D. Take measurement at 10mm from the bottom and 90° to the piston pin hole. 10 mm Service Limit (replace if below): 72.6 mm (2.904 in) Measure the piston-to-piston pin clearance. Service Limit (replace if over): 0.02 mm (0.0008 in)
  • Page 139 . CYLINDER/PISTON MXU 300/250 PISTON RING INSTALLATION Install the piston rings onto the piston. Apply engine oil to each piston ring. • Be careful not to damage or break the piston and piston rings. • All rings should be installed with the markings facing up.
  • Page 140 . CYLINDER/PISTON MXU 300/250 Intake Side Guide Inspect the exhaust side and intake side chain guides. Wear/Damage → Replace. Exhaust Side Guide PISTON INSTALLATION “IN” Mark Remove any gasket material from the crankcase surface. Be careful not to drop foreign matters into the crankcase.

  • Page 141: Drive And Driven Pulleys

    DRIVE AND DRIVEN PULLEYS MXU 300/250 DRIVE AND DRIVEN PULLEYS SERVICE INFORMATION..............9-2 TROUBLESHOOTING................9-2 LEFT CRANKCASE COVER ..............9-3 DRIVE PULLEY/DRIVEN PULLEY ............ 9-4...
  • Page 142 DRIVE AND DRIVEN PULLEYS MXU 300/250...

  • Page 143: Service Information

    DRIVE AND DRIVEN PULLEYS MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • The drive pulley, clutch and driven pulley can be serviced with the engine installed in the frame. • Avoid getting grease and oil on the drive belt and pulley faces. Remove any oil or grease from them to minimize the slipping of drive belt and drive pulley.

  • Page 144: Left Crankcase Cover

    DRIVE AND DRIVEN PULLEYS MXU 300/250 Bolts LEFT CRANKCASE COVER REMOVAL Remove the five bolts. Remove the recoil starter cover. Recoil Starter Cover Gasket Remove the dowel pins and gasket. Dowel Pins Bolts Disconnect drive belt air inlet and outlet hose from left crankcase cover (see page 6-5).

  • Page 145: Drive Pulley/Driven Pulley

    DRIVE AND DRIVEN PULLEYS MXU 300/250 INSPECTION Bearing Inspect the bearing for allow play in the left crankcase cover or the bearing turns roughly → Replace. Gasket INSTALLATION Install the dowel pins and new gasket. Reverse the “LEFT CRANKCASE COVER REMOVAL”...
  • Page 146 DRIVE AND DRIVEN PULLEYS MXU 300/250 Remove the left crankcase cover. (Refer to the “LEFT CRANKCASE COVER REMOVAL” section in the chapter 9) Remove the drive pulley. (Refer to the “DRIVE PULLEY REMOVAL” section in the chapter 9) Hold the clutch outer with the universal holder and remove the clutch outer nut.
  • Page 147 DRIVE AND DRIVEN PULLEYS MXU 300/250 Drive Face Remove the movable drive face assembly and drive pulley collar. Drive Pulley Collar Ramp Plate DISASSEMBLY Remove the ramp plate. Roller Remove the six weight rollers.
  • Page 148 DRIVE AND DRIVEN PULLEYS MXU 300/250 INSPECTION Check each weight roller for wear or damage. Measure each weight roller O.D. Service Limit (replace if below): 22.8 mm (0.912 in) Measure the movable drive face bushing I.D. Service Limit (replace if over): 27.06 mm (1.0824 in)
  • Page 149 DRIVE AND DRIVEN PULLEYS MXU 300/250 DRIVE BELT INSPECTION Check the drive belt for cracks, separation or abnormal or excessive wear. Measure the drive belt width. Service Limit (replace if below): 22 mm (0.88 in) Use specified genuine parts for replacement.
  • Page 150 DRIVE AND DRIVEN PULLEYS MXU 300/250 Loosen the clutch spring compressor and disassemble the clutch/driven pulley assembly. Remove the seal collar. O-ring Guide Roller Pin Pull out the guide roller pins and guide rollers. Remove the movable driven face from the driven face.
  • Page 151 DRIVE AND DRIVEN PULLEYS MXU 300/250 Measure the clutch lining thickness. Service Limit (replace if below): 0.5 mm (0.02 in) INSPECTION Measure the driven face spring free length. Service Limit (replace if below): 131 mm (5.24 in) Check the driven face for wear or damage.
  • Page 152 DRIVE AND DRIVEN PULLEYS MXU 300/250 Check the movable driven face for wear or damage. Measure the movable driven face I.D. Service Limit (replace if over): 40.06 mm (1.6024 in) Inner Bearing DRIVEN PULLEY FACE BEARING REPLACEMENT Drive the inner needle bearing out of the driven pulley face.
  • Page 153 DRIVE AND DRIVEN PULLEYS MXU 300/250 Seat the snap ring in its groove. Apply grease to the driven face bore areas. Pack all bearing cavities with proper grease. Specified grease: Heat resistance 230°C Press a new needle bearing into the driven face.
  • Page 154 DRIVE AND DRIVEN PULLEYS MXU 300/250 Install the damper rubbers on the drive plate pins. Install the clutch weights/shoes and clutch springs onto the drive plate. Install the retainer plate and secure with the circlips. Clean the driven pulley faces and remove any grease from them.
  • Page 155 DRIVE AND DRIVEN PULLEYS MXU 300/250 INSTALLATION Install the drive pulley face assembly and collar. Install the clutch/driven pulley and driven belt onto the drive shaft. Keep grease off the drive shaft. Install the clutch outer, collar. Hold the clutch outer with the flywheel holder.
  • Page 156 DRIVE AND DRIVEN PULLEYS MXU 300/250 Install the drive pulley and ratchet. When installing the drive pulley face, compress it to let the drive belt move downward to the lowest position so that the drive pulley can be tightened. Make sure the ratchet into the splines on the crankshaft when the ratchet is installed.
  • Page 157 TROUBLESHOOTING----------------------------------------------------- 10- 3 TRANSMISSION CASE COVER (MXU 250)-------------------------------- 10- 4 TRANSMISSION (MXU 250)--------------------------------------------- 10- 6 SPEEDOMETER GEAR --------------------------------------------------- 10-16 TRANSMISSION CASE COVER/SECONDARY DRIVEN BEVEL GEAR ASSEMBLY (MXU 300) ------------------------------------------ 10-18 TRANSMISSION (MXU 300)--------------------------------------------- 10-29 SECONDARY GEAR SHIMS (MXU 300) ------------------------------ 10-39 10-0...
  • Page 158 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 MXU 250 10-1...
  • Page 159 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM MXU 300 10-2...

  • Page 160: Final Reduction/Transmission System

    • The MXU 250 transmission system can be serviced with the engine installed in the frame. • The MXU 300 transmission system can be serviced with the engine removed from the frame. • When replacing the drive shaft, use a special tool to hold the bearing inner race for this operation.

  • Page 161: Transmission Case Cover (Mxu 250)

    .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM TRANSMISSION CASE COVER (MXU 250) REMOVAL Drain transmission gear oil into a clean container. (Refer to the “TRANSMISSION OIL REPLACEMENT” section in the chapter Remove the three bolts and then remove the drive sprocket cover (see page 6-3).
  • Page 162 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Bearing Bearing Circlip TRANSMISSION CASE COVER DISASSEMBLY Remove the drive axle circlip. Remove the drive axle from the transmission case cover. Remove the bearing circlip for remove the bearing. Inspect the bearing for allow play in the...

  • Page 163: Transmission (Mxu 250)

    .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Needle Bearing Inspect the needle bearing for allow play in the transmission case cover or the bearing turns roughly. If any defects are found, replace the bearing with a new one. Needle Bearing ASSEMBLY Install the needle bearing.
  • Page 164 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Shift Shaft Remove the shift shaft. Remove the stopper plug. Plug Washer Shift Cam Stopper Remove spring, washer and shift cam stopper. Plug Spring 10-7...
  • Page 165 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Guide Bar Remove the transmission guide bar. Shift Cam Remove shift cam. Shift Fork Remove the shift fork. 10-8...
  • Page 166 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Measure the guide bar runout. Out of specification → Replace. Service Limit: Less than 0.03 mm (0.0012 in) Do not attempt to straighten a bent guide bar. Shift Fork Cam Follower Inspect the shift fork cam follower and shift fork pawl.
  • Page 167 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Shift Shaft Inspect shift shaft gear. Damage → Replace. Inspect shift shaft. Damage/bends/wear → Replace. Shift Shaft Gear Remove the main axle. Main Axle Clutch Dog Collar MAIN AXLE DISASSEMBLY Remove the washers, collar, primary driven gear, bush and clutch dog.
  • Page 168 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Primary Driven Gear Collar Bush Washers Clutch Dog Main Axle Reverse Wheel Gear Remove the circlip and then remove the washers, reverse wheel gear and needle bearing. Circlip Washer Reverse Wheel Gear Needle Bearing...
  • Page 169 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Inspect the gear teeth. Blue discoloration/pitting/wear → Replace. Inspect the mated dogs. Rounded edges/cracks/missing portions → Replace. MAIN AXLE ASSEMBLY Reverse the “MAIN AXLE DISASSEMBLY” procedures. Reverse Wheel Gear Circlip Clutch Dog Primary Driven Gear...
  • Page 170 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Remove the counter axle. Counter Axle Inspect the gear teeth. Blue discoloration/pitting/wear → Replace. Primary Drive Axle Bolts Oil Seal PRIMARY DRIVE AXLE REMOVAL Remove the clutch/driven pulley. (Refer to the chapter 9) Remove the oil seal, circlip, bolts and plates.
  • Page 171 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Bearings Inspect the bearings for allow play in the transmission case cover or the bearing turns roughly. If any defects are found, replace the bearing with a new one. Washer INSTALLATION Reverse the “TRANSMISSION REVOVAL”...
  • Page 172 Fill the engine with oil and install the oil filler bolt. (Refer to the “TRANSMISSION OIL REPLACEMENT” section in the chapter Gasket Specified Gear Oil: KYMCO SIGMA GEAR OIL 90# Oil Capacity (MXU 250): At disassembly: 0.4 liter (0.352 lmp qt, 0.424 US qt) At change: 0.3 liter (0.264 lmp qt, 0.318 US qt)

  • Page 173: Speedometer Gear

    .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM SPEEDOMETER GEAR REMOVAL Disconnect the speedometer cable (see page 6-3). Remove the speedometer gear plug, washer and speedometer gear shaft. Plug Washer INSPECTION Inspect the speedometer gear teeth. pitting/wear → Replace. Plug Speedometer Gear Remove the transmission case cover (see page 10-4).
  • Page 174 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Inspect the oil seal for wear or damage. If any defects are found, replace the oil seal with a new one. Oil Seal INSTALLATION Reverse the “REMOVAL” procedures. 10-17...

  • Page 175: Transmission Case Cover/Secondary Driven Bevel Gear Assembly (Mxu 300)

    MXU 300/250 TRANSMISSION SYSTEM Band Screw TRANSMISSION CASE COVER / SECONDARY DRIVEN BEVEL GEAR ASSEMBLY (MXU 300) REMOVAL Drain transmission gear oil into a clean container. (Refer to the “TRANSMISSION OIL REPLACEMENT” section in the chapter Remove the engine assembly (Refer to the “ENGINE REMOVAL”...
  • Page 176 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Remove the three bolts and secondary drive Secondary Drive Bevel Gear Cover bevel gear cover. Bolts Speedometer Gear Remove the speedometer gear plug, washer and speedometer gear. Plug Washer Clutch Outer Using a chisel, unlock the nut.
  • Page 177 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Secondary Drive Bevel Gear/Shim Remove the eight bolts, then remove the transmission case cover, gasket and secondary drive bevel gear/shim. Transmission Case Cover/Gasket Remove the two dowel pins. Dowel Pins Driven Bevel Gear Shaft Nut...
  • Page 178 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Secondary Driven Bevel Gear Shim Remove the secondary driven bevel gear and shim. Secondary Driven Bevel Gear Shaft Remove the secondary driven bevel gear shaft from case. Shift Shaft Oil Seal TRANSMISSION CASE COVER...
  • Page 179 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Set Plate Remove the two bolts and driveshaft bearing set plate. Bolts Driveshaft Bearing Remove the countershaft bearing and driveshaft bearing with special tools. Special tools: Bearing puller E037 Bearing/Oil seal install E014 Countershaft Bearing...
  • Page 180 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 SECONDARY DRIVEN BEVEL GEAR Oil Seal Snap Ring SHAFT CASE BEARING/OIL SEAL REPLACEMENT Remove the secondary driven bevel gear shaft oil seal. Remove the snap ring. Outer Bearing Remove the outer bearing. Snap Ring Inner Bearing Remove the snap ring.
  • Page 181 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Inner Bearing Snap Ring Install a new inner bearing with the special tool. Special tools: Bearing/Oil seal install E014 Outer Bearing Snap Ring Install a new outer bearing with special tool. Special tools: Bearing/Oil seal install E014...
  • Page 182 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Splines INSPECTION Inspect the secondary driven bevel gear shaft splines for wear or damage. Inspect the secondary driven bevel gear shaft for blue discoloration, pitting or wear. Inspect the bevel gears and speedometer gear...
  • Page 183 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Shim Driven Bevel Gear Apply engine oil to the driven bevel gear. Install the shim and driven bevel gear. Fit the universal joint onto the driven bevel gear shaft. Tighten the driven bevel gear nut to the specified torque.
  • Page 184 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Transmission Cover/Gasket Install the gasket and transmission case cover. Install and tighten the bolts to the specified torque. Torque: 2.7 kgf-m (27 Nm, 20 lbf-ft) Shim Drive Bevel Gear Install the shim and drive bevel gear.
  • Page 185 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Replace a new O-ring and apply engine oil to the O-ring. Install the secondary driven bevel gear into the transmission case cover. Align the mark on the secondary bevel driven gear shaft case with the index mark on the transmission case cover.

  • Page 186: Transmission (Mxu 300)

    Fill the engine with oil and install the oil filler bolt. (Refer to the “TRANSMISSION OIL REPLACEMENT” section in the chapter Specified Gear Oil: KYMCO SIGMA GEAR OIL 90# Bolts Oil Capacity (MXU 300): At disassembly: 0.6 liter (0.528 lmp qt, 0.636 US qt) At change: 0.5 liter (0.44 lmp qt, 0.53 US qt)
  • Page 187 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Guide Bar Upper Shift Fork Remove the transmission guide bar. Remove the upper shift fork. Shift Cam Lower Shift Fork Remove the shift cam. Remove the lower shift fork. Washer Plug Countershaft Driveshaft Remove the countershaft and driveshaft as an assembly.
  • Page 188 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 INSPECTION Measure the guide bar runout. Out of specification → Replace. Service Limit: Less than 0.03 mm (0.0012 in) Do not attempt to straighten a bent guide bar. Shift Fork Cam Follower Inspect the shift fork cam follower and shift fork pawl.
  • Page 189 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Gearshifter Groove Washer COUNTERSHAFT DISASSEMBLY/INSPECTION Remove the washer and high gear clutch dog. Clutch dog Check the gear dogs, gearshifter groove for wear or damage. Gear Dogs Clutch Dog Remove the snap ring, then remove washer...
  • Page 190 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Countershaft Remove the washer. Countershaft Inspect the teeth, spline grooves and sliding surfaces for abnormal wear or damage. ASSEMBLY Clean all parts in solvent. Washer Apply molybdenum oil solution to the gear and sliding surface and shift fork grooves to ensure initial lubrication.
  • Page 191 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM DRIVESHAFT DISASSEMBLY/INSPECTION Remove the washer. Remove the reverse gear. Reverse gear Inspect the dog holes and teeth for damage or wear. Washer Reverse Gear Gear Dogs Gearshifter Groove Washer Remove the washer. Remove the reverse/low gear clutch dog.
  • Page 192 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Low Driven Gear Remove the low driven gear, then remove the washer. Low driven gear Inspect the dog holes and teeth for damage or wear. Washer ASSEMBLY Clean all parts in solvent. Apply molybdenum oil solution to the gear and sliding surface and shift fork grooves to ensure initial lubrication.
  • Page 193 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM Primary Drive Axle Bolts Oil Seal PRIMARY DRIVE AXLE REMOVAL Remove the clutch/driven pulley. (Refer to the chapter 9) Remove the oil seal, circlip, bolts and plates. Remove the primary drive axle. Plates Circlip...
  • Page 194 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Install the new bearings with special tool. Special tools: Bearing/Oil seal install E014 Bearings INASTALLATION Apply engine oil to the following parts: Countershaft. Driveshaft. Gear teeth. Assemble the countershaft and driveshaft. Install the countershaft, driveshaft assemblies as a set into the transmission case.
  • Page 195 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM “ LCD9L” Mark Lower Gearshift Fork Apply engine oil to the gearshift fork, sliding surfaces and gearshift fork pawl. Install the lower gearshift fork into the clutch dog (counter axle) groove with its “LCD9L”...

  • Page 196: Secondary Gear Shims (Mxu 300)

    .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Secondary Drive Bevel Gear Cover SECONDARY GEAR SHIMS (MXU 300) Remove the for bolts and secondary drive bevel gear cover. Bolts Drive Bevel Gear Driven Bevel Gear Set a dial gauge on the driven bevel gear as shown.
  • Page 197 .FINAL REDUCTION/ MXU 300/250 TRANSMISSION SYSTEM TOOTH CONTACT After backlash adjustment is carried out, the tooth contact must be checked. Pay attention to the following procedures: ● Remove the driven bevel gear. ● Clean and degrease several teeth of the drive and driven bevel gears.
  • Page 198 .FINAL REDUCTION/ TRANSMISSION SYSTEM MXU 300/250 Drive Bevel Gear Shim Drive bevel gear shims: A: 0.6 mm (0.024 in) B: 0.65 mm (0.026 in) C: 0.7 mm (0.028 in) D: 0.75 mm (0.03 in) E: 0.8 mm (0.032 in) Driven Bevel Gear F: 0.85 mm (0.034 in)

  • Page 199: Crankcase/Crankshaft/Balance Shaft

    .CRANKSCASE/CRANKSHAFT/ BALANCE SHAFT MXU 300/250 __________________________________________________________________________________ CRANKCASE/CRANKSHAFT/BALANCE SHAFT SERVICE INFORMATION------------------------------------------------ 11- 2 TROUBLESHOOTING----------------------------------------------------- 11- 2 CRANKCASE/CRANKSHAFT/BALANCE SHAFT ------------------ 11- 3 11-0...
  • Page 200 .CRANKCASE/CRANKSHAFT/ BALANCE SHAFT MXU 300250 11-1...

  • Page 201: Balance Shaft

    .CRANKSCASE/CRANKSHAFT/ BALANCE SHAFT MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • This section covers crankcase separation to service the crankshaft. The engine must be removed for this operation. • The following parts must be removed before separating the crankcase. −Cylinder head ( Chapter 7) −Cylinder/piston ( Chapter 8)
  • Page 202 .CRANKCASE/CRANKSHAFT/ BALANCE SHAFT MXU 300250 Timing Chain CRANKCASE/CRANKSHAFT/BA LANCE SHAFT REMOVAL Remove the timing chain from right crankcase. Bolts Remove the left and right crankcase attaching bolts. Separate the left and right crankcase halves. Do not damage the crankcase gasket surface.
  • Page 203 .CRANKSCASE/CRANKSHAFT/ BALANCE SHAFT MXU 300/250 Balance Shaft Remove balance shaft from the left crankcase. Clean off all gasket material from the crankcase mating surfaces. Avoid damaging the crankcase mating surfaces. Inspect the balance shaft gear teeth. Burrs/chips/roughness/wear → Replace. 11-4...
  • Page 204 .CRANKCASE/CRANKSHAFT/ BALANCE SHAFT MXU 300250 CRANKSHAFT INSPECTION Inspect the crankshaft gear teeth. Burrs/chips/roughness/wear → Replace. Measure the connecting rod small end I.D. Service Limit (replace if over): 17.06 mm (0.6824 in) Measure the connecting rod small end free play (A). Out of specification: 0.8 ~ 1 mm (0.032 ~ 0.04 in) →...
  • Page 205 .CRANKSCASE/CRANKSHAFT/ BALANCE SHAFT MXU 300/250 Turn the crankshaft bearings and check for Play excessive play. Play Measure the crankshaft bearing play. Service Limit (replace if over): Axial : 0.2 mm (0.008 in) Radial : 0.05 mm (0.002 in) Radial Axial...

  • Page 206: Cooling System

    . COOLING SYSTEM MXU 300/250 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ COOLING SYSTEM __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 12- 1 TROUBLESHOOTING----------------------------------------------------- 12- 1 COOLING SYSTEM TESTING------------------------------------------- 12- 3 RADIATOR ------------------------------------------------------------------ 12- 4 COOLANT REPLACEMENT --------------------------------------------- 12- 7 WATER PUMP -------------------------------------------------------------- 12- 9 THERMOSENSOR---------------------------------------------------------- 12-13...

  • Page 207: Cooling System

    . COOLING SYSTEM MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • The water pump must be serviced after removing the engine. Other cooling system service can be done with the engine installed in the frame. • The engine must be cool before servicing the cooling system.
  • Page 208 975cc -44.5 Cautions for Using Coolant: • Use coolant of specified mixing rate. (The mixing rate of 425cc KYMCO SIGMA coolant concentrate + 975cc distilled water is 30%.) • Do not mix coolant concentrate of different brands. • Do not drink the coolant which is poisonous.

  • Page 209: Cooling System Testing

    . COOLING SYSTEM MXU 300/250 COOLING SYSTEM TESTING RADIATOR CAP INSPECTION Radiator Tester Install the radiator cap onto the radiator tester and apply specified pressure to it. It must hold specified pressure for at least six seconds. Apply water to the cap sealing surface before testing.

  • Page 210: Radiator

    . COOLING SYSTEM MXU 300/250 RADIATOR RADIATOR INSPECTION Remove the front fender. ( page 2-8) Inspect the radiator soldered joints and seams for leaks. Blow dirt out from between core fins with compressed air. If insects, etc., are clogging the radiator, wash them off.
  • Page 211 . COOLING SYSTEM MXU 300/250 Remove the two bolts on the radiator. Pull radiator forward and raise the radiator from frame. Bolts Fan Motor Connector Radiator Hoses Disconnect the thermostatic switch wire connectors. Disconnect the fan motor connector. Loosen the hose bands and disconnect the coolant hoses from the radiator.
  • Page 212 . COOLING SYSTEM MXU 300/250 Bolts RADIATOR DISASSEMBLY Remove the three bolts and then remove the fan shroud from the radiator. Check fan motor by battery. CHECK THERMOSTATIC SWITCH When coolant temperature lower then 85~90 the thermostatic switch OFF. When coolant temperature over 85~90 the thermostatic switch ON.

  • Page 213: Coolant Replacement

    . COOLING SYSTEM MXU 300/250 COOLANT REPLACEMENT PREPARATION ● The effectiveness of coolant decreases with the accumulation of rust or if there is a change in the mixing proportion during usage. Therefore, for best performance change the coolant regularly as specified in the maintenance schedule.
  • Page 214 . COOLING SYSTEM MXU 300/250 Maximum Mark Minimum Mark Remove the reserve tank cap and drain the coolant from the reserve tank. Reinstall the drain bolt with the new sealing washer securely. Place the vehicle on a flat, level surface.

  • Page 215: Water Pump

    . COOLING SYSTEM MXU 300/250 WATER PUMP MECHANICAL SEAL (WATER SEAL) INSPECTION Inspect the telltale hole for signs of mechanical seal coolant leakage. If the mechanical seal is leaking, remove the right crankcase cover and replace the mechanical seal. Water Pump...
  • Page 216 . COOLING SYSTEM MXU 300/250 Impeller Mechanical Seal Inspect the mechanical (water) seal and seal washer for wear or damage. The mechanical seal and seal washer must be replace as a set. Seal Washer (Porcelain) WATER PUMP SHAFT REMOVAL Remove the water pump impeller. ( page 12- Disconnect the water hose from the right crankcase cover.
  • Page 217 . COOLING SYSTEM MXU 300/250 Impeller Washer Inner Bearing Snap Ring Remove the water pump shaft outer bearing. Outer Bearing Water Pump Shaft Seal Washer Water Pump Assembly MECHANICAL SEAL REPLACEMENT Drive the mechanical seal out of the water pump assembly from the inside.
  • Page 218 . COOLING SYSTEM MXU 300/250 Outer Bearing WATER PUMP SHAFT INSTALLATION Drive a new water pump shaft outer bearing into the water pump assembly from the inside. Water Pump Assembly Install the water pump shaft and shaft inner bearing into the waster pump assembly.

  • Page 219: Thermosensor

    . COOLING SYSTEM MXU 300/250 THERMOSENSOR THERMOSENSOR REMOVAL Drain the coolant. ( page 12-7 ) Disconnect the thermosensor wire. Remove the thermosensor from the thermostat. Thermosensor Thermosensor Connectsor THERMOSENSOR INSPECTION Thermosensor Suspend the thermosensor in a pan of water over a burner and measure the resistance through the sensor as the water heats up.

  • Page 220: Thermostat

    . COOLING SYSTEM MXU 300/250 Thermostat Bolts Air Vent Tube THERMOSTAT THERMOSTAT REMOVAL Drain the coolant. ( page 12-7) Disconnect the thermosensor wire from the thermosensor. Disconnect the water hose from the thermostat housing. Disconnect the air vent tube from the thermostat housing.
  • Page 221 . COOLING SYSTEM MXU 300/250 THERMOSTAT INSPECTION Suspend the thermostat in a pan of water over a burner and gradually raise the water Thermostat temperature to check its operation. Technical Data Thermometer Begins to open 80±2 Full-open Valve lift 3.5～4.5 mm O-ring •...

  • Page 222: Brake System

    . BRAKE SYSTEM MXU 300/250 __________________________________________________________________________________ BRAKE SYSTEM SERVICE INFORMATION------------------------------------------------ 13- 2 TROUBLESHOOTING----------------------------------------------------- 13- 2 FRONT HYDRAULIC BRAKE------------------------------------------- 13- 3 FRONT BRAKE FLUID CHANGE/AIR BLEED ---------------------- 13- 4 BRAKE MASTER CYLINDER -------------------------------------------- 13- 6 FRONT BRAKE CALIPER ------------------------------------------------ 13- 9...
  • Page 223 . BRAKE SYSTEM MXU 300/250 13-1...

  • Page 224: Brake System

    . BRAKE SYSTEM MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • During servicing, keep oil or grease off the brake pads and brake disk. • Drain the brake fluid from the hydraulic brake system before disassembly. • Contaminated brake disk or brake pads reduce stopping power. Clean the contaminated brake disk with high-performance brake degreaser and replace the brake pads.

  • Page 225: Front Hydraulic Brake

    . BRAKE SYSTEM MXU 300/250 FRONT HYDRAULIC BRAKE BRAKE PADS REMOVAL Remove the front wheel. ( page 14-3) Remove the two brake pad pins from the brake caliper. Remove the two bolts attaching the brake caliper and then remove brake caliper.

  • Page 226: Front Brake Fluid Change/Air Bleed

    . BRAKE SYSTEM MXU 300/250 BRAKE DISK Measure the brake disk thickness. Service Limit: 3 mm (0.12 in) Measure the brake disk run out. Service Limit: 0.3 mm (0.012 in) INSTALLATION Reverse the “BRAKE PADS REMOVAL” procedures. Torque: Brake pad pin bolt: 1.8 kgf-m (18 Nm, 13 lbf-ft)
  • Page 227 . BRAKE SYSTEM MXU 300/250 Reservoir BRAKE FLUID REFILLING Connect a transparent hose and syringe to the brake caliper bleed valve and then loosen the bleed valve nut. Fill the brake reservoir with brake fluid and use the syringe to draw brake fluid into it until there is no air bubbles in the hose.

  • Page 228: Brake Master Cylinder

    . BRAKE SYSTEM MXU 300/250 Fluid Tube Bolt BRAKE MASTER CYLINDER DISASSEMBLY Remove the brake reservoir cover Drain the brake fluid from the hydraulic brake system. ( page 13-4) Do not splash brake fluid onto any rubber, plastic and coated parts. When working with brake fluid, use shop towels to cover these parts.
  • Page 229 . BRAKE SYSTEM MXU 300/250 Spring Master Cylinder Main Piston Remove the washer, main piston and spring from the brake master cylinder. Clean the inside of the master cylinder and brake reservoir with brake fluid. Snap Ring Rubber Cover INSPECTION...
  • Page 230 . BRAKE SYSTEM MXU 300/250 ASSEMBLY Before assembly, apply brake fluid to all removed parts. • During assembly, the main piston and spring must be installed as a unit without exchange. • When assembling the piston, soak the cups in brake fluid for a while.

  • Page 231: Front Brake Caliper

    . BRAKE SYSTEM MXU 300/250 FRONT BRAKE CALIPER REMOVAL Remove the front wheel. ( page 14-3 ) First drain the brake fluid from the hydraulic brake system. ( page 13-4) Remove the brake pad pins. Remove the brake fluid tube bolt.
  • Page 232 . BRAKE SYSTEM MXU 300/250 Push the piston dust seal inward to remove. Dust Seal Inner Oil Seal Pushing the piston oil seal outward to remove it. Clean the seals groove with brake fluid. Be careful not to damage the piston surface.
  • Page 233 . BRAKE SYSTEM MXU 300/250 Wipe off excessive brake fluid with a clean shop towel. Install the caliper spring plate into the caliper. Make sure that the boss on the caliper correctly engages with the locating slot on the caliper spring plate.

  • Page 234: Rear Hydraulic Brake

    Brake Pad Pin Spring Plate Small End Brake Pad Pins Brake Pad Pins REAR BRAKE PADS (MXU 300) Replacement Remove the left rear wheel (page 15-4). The rear and front brake pads are replaced the same (page 13-3).
  • Page 235 . BRAKE SYSTEM MXU 300/250 Reservoir Cover (Pedal) BRAKE FLUID DRAINING Place the machine on the level ground. Remove the two screws attaching the brake fluid reservoir cap (brake lever and brake pedal). Use shop towels to cover plastic parts and coated surfaces to avoid damage caused by splash of brake fluid.
  • Page 236 . BRAKE SYSTEM MXU 300/250 Bleed Valve (Front Left Lever) BRAKE FLUID REFILLING Connect a transparent hose and syringe to the brake caliper bleed valve and then loosen the bleed valve nut. Fill the brake reservoir with brake fluid and use the syringe to draw brake fluid into it until there is no air bubbles in the hose.
  • Page 237 . BRAKE SYSTEM MXU 300/250 BRAKE SYSTEM BLEEDING Connect a transparent hose to the bleed valve and fully apply the brake lever (pedal) after continuously pull it several times. Then, loosen the bleed valve nut to bleed air from the brake system. Repeat these steps until the brake system is free of air.

  • Page 238: Rear Brake Master Cylinder (Rear Brake Pedal)

    . BRAKE SYSTEM MXU 300/250 REAR BRAKE MASTER CYLINDER (REAR BRAKE PEDAL) REAR MASTER CYLINDER ON THE LEFT HANDGRIP DISASSEMBLY Refer to the “FRONT BRAKE MASTER CYLINDER DISASSEMBLY” section in the chapter 13. ASSEMBLY Refer to the “FRONT BRAKE MASTER CYLINDER ASSEMBLY”...
  • Page 239 . BRAKE SYSTEM MXU 300/250 Remove the screw and remove the fluid Screw Fluid Inlet Duct inlet duct. Check the O-ring for wear or damage and replace if necessary. O-ring Seal Boot Remove the two nuts and remove the seal boot.
  • Page 240 . BRAKE SYSTEM MXU 300/250 Spring INSPECTION Check the cylinder inside wall, and spring for scratch, corrosion or other abnormal condition. If any abnormal condition is found, replace the inner parts or master cylinder. Before assembly, inspect the lst and 2nd rubber cups for wear.

  • Page 241: Rear Brake Caliper

    . BRAKE SYSTEM MXU 300/250 REAR BRAKE CALIPER REMOVAL (MXU 250) Drain brake fluid of both the rear brake side and the combination brake side. ( page 13- To prevent brake fluid from splashing on the parts nearby, cover the parts with cloth.
  • Page 242 . BRAKE SYSTEM MXU 300/250 Seals Remove the dust seals and piston seals. Use care not to cause scratch on the cylinder bore. Do not reuse the piston seal and dust seal that have been removed. Piston INSPECTION (MXU 250)
  • Page 243 . BRAKE SYSTEM MXU 300/250 ASSEMBLY (MXU 250) Reassemble the caliper in the reverse order of disassembly procedures and observe the following points. Wash the caliper components with fresh brake fluid before assembly. Do not wipe off brake fluid after washing the components.
  • Page 244 . BRAKE SYSTEM MXU 300/250 Caliper (Pedal) Caliper (Front Brake Lever) REMOVAL/INSPECTION/ASSEMBLY/ INSTALLATION (MXU 300) Remove the rear left wheel (page 15-4). The rear and calipers are all the same removal/inspection/assembly/installation. Bolts Bolts 13-22...
  • Page 245 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 __________________________________________________________________________________ FRONT WHEEL/ FRONT SUSPENSION\STEERING SYSTEM SERVICE INFORMATION------------------------------------------------ 14- 2 TROUBLESHOOTING----------------------------------------------------- 14- 2 FRONT WHEEL------------------------------------------------------------- 14- 3 FRONT WHEEL HUB------------------------------------------------------ 14- 4 FRONT SUSPENSION ----------------------------------------------------- 14- 8 TIE-ROD---------------------------------------------------------------------- 14-15 HANDLEBAR --------------------------------------------------------------- 14-18 STEERING COLUMN------------------------------------------------------ 14-21...

  • Page 246: Front Wheel/Front Suspension/Steering System

    FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 14-1...
  • Page 247 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • Jack the machine front wheel off the ground and be careful to prevent the machine from falling down. • During servicing, keep oil or grease off the brake disk •...
  • Page 248 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Nuts FRONT WHEEL REMOVAL AND INSPECTION Place the machine on a level place. Remove four nuts attaching the front wheel hub and front wheel. Elevate the front wheels by placing a suitable stand under the frame.
  • Page 249 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Cotter Pin FRONT WHEEL HUB REMOVAL AND INSPECTION Place the machine on a level place. Remove the front wheel ( page 14-3) and caliper. ( page 13-9) Elevate the front wheels by placing a suitable stand under the frame.
  • Page 250 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Bearing Inspect the bearings for allow play in the front wheel hub or the wheel turns roughly. Bearing If any defects are found, replace the bearings. Remove the bearings using a general bearing puller.
  • Page 251 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Distance Collar Remove the distance collar from the front wheel hub. ASSEMBLY Install the left new bearing and dust seal into the front wheel hub. Special tool: Oil seal and bearing install E014 Apply the grease onto the oil seal lips, bearing.
  • Page 252 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Install the right new bearing and dust seal into the front wheel hub. Apply the grease onto the oil seal lips, bearing. Special tool: Oil seal and bearing install E014 • Do not allow the bearings to tilt while driving them in.

  • Page 253: Front Suspension

    FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 FRONT SUSPENSION REMOVAL AND INSPECTION Elevate the front wheels by placing a suitable stand under the frame. Support the machine securely so there is no danger of it falling over. Remove the front wheel ( page 14-3), caliper ( page 13-9) and front wheel hub.
  • Page 254 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Apply grease Release the ball joints of the upper and lower arms off the knuckle, using the special tool according to the following instructions. Special tool: Ball join remover F012 Apply grease to the ball joint remover at the point shown.
  • Page 255 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Bolts/Nuts Remove the front shock absorber upper mount and lower mount bolts/nuts, then remove the front shock absorber and bush. Bush Inspect the shock absorber rod. Bends/damage →Replace the shock absorber assembly. Inspect the shock absorber.
  • Page 256 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Check the upper front arm brackets of the frame. If bent, cracked or damaged, repair or replace the frame. Check the tightening torque of the front arms securing nuts. Torque: 4.5 kgf-m (45 Nm, 32 lbf-ft) Check the upper front arm side play by moving it from side to side.
  • Page 257 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Inspect the front arm. Bushes Cracks/bends/damage →Replace. Do not attempt to straighten a bent arm, this may dangerously weaken the arm. Inspect bushes. Wear/damage →Replace. Check the lower front arm brackets of the frame.
  • Page 258 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Bolts Remove the two nuts and two bolts attaching the lower front arm, then remove the lower front arm and bushes. Bushes Inspect the lower front arm. Cracks/bends/damage →Replace. Do not attempt to straighten a bent arm, this may dangerously weaken the arm.
  • Page 259 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 INSTALLATION Reverse the “FRONT SUSPENSION REMOVAL AND INSPECTION” procedures. Apply the grease onto the bushes and inner collars Install the lower and upper front arms nuts onto the frame and tighten the nuts.
  • Page 260 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 TIE-ROD REMOVAL/INSPECTION Remove the cotter pin and nut attaching the tie-rod and steering column. Remove the cotter pin, washer and nut attaching the tie-rod and steering knuckle. Then remove tie-rods, using the special tool (page 14-8).
  • Page 261 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Adjust the tie-rod length. Adjustment steps: (The following procedures are done on both tie-rods, right and left.) Loosen the lock nuts. Adjust the tie-rod length by tuning both tie- rod ends. Tie rod length: 299.5±0.5 mm (11.98±0.02 in)
  • Page 262 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 INSTALLATION Reverse the “REMOVAL/INSPECTION” procedures. Install the tie-rod and washer onto the steering knuckle and steering column, then tighten the nuts. Torque: Steering knuckle side: 2 kgf-m (20 Nm, 15 lbf-ft) Indentation Surface...
  • Page 263 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 HANDLEBAR REMOVAL/INSPECTION Remove the following parts: Seat, front cover, fuel tank cover, front fender and handlebar cover. Refer to the “FENDERS” section in the CHAPTER 2 Remove the right and left master cylinder and remove bands then disconnect the rear and front fluid tube from the handlebar.
  • Page 264 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 INSPECTION Inspect the handlebar. Cracks/bends/damage →Replace. Holder Surface INSTALLATION Install handlebar and handlebar holder, then tighten the four bolts. Torque: 2.5 kgf-m (25 Nm, 18 lbf-ft) Align the mark on the handlebar with the lower handlebar holder surface.
  • Page 265 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Hole Install the handlebar switch by aligning the pin on the handlebar switch with the hole in the handlebar and then tighten the two screws. “UP” Mark Place the right and left brake master cylinder on the handlebar and install the master cylinder holder with the “UP”...
  • Page 266 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Install the throttle unit by aligning the upper Mark holder lip with the mark in the handlebar and then install the lower holder and tighten the two screws. Upper Holder Lip STEERING COLUMN REMOVAL AND INSPECTION Remove handlebar.
  • Page 267 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Remove the cotter pins and nuts attaching the tie-rods, then disconnect the tie-rods from the steering column. Cotter Pin Remove the cotter pin and nut attaching the steering column under the frame body, then remove steering column and collar.
  • Page 268 FRONT WHEEL/FRONT SUSPENSION/ STEERING SYSTEM MXU 300/250 Inspect the steering column. Bends/damage →Replace. Do not attempt to straighten a bent shaft, this may dangerously weaken the shaft. Inspect the steering brackets and oil seal. Wear damage →Replace. INSTALLATION Reverse the “REMOVAL” procedures.

  • Page 269: Rear Wheel/Axle/Suspension/ Driving Mechanism

    INSPECTION ---------------------------------------------------------------- 15- 21 FINAL DRIVE SHIM (MXU 300) ADJUSTMENT/FINAL GEAR CASE (MXU 300) DISASSEMBLY-------------------------------------- 15- 26 FINAL GEAR CASE (MXU 300) ASSEMBLY ------------------------ 15- 36 SWINGAEM (MXU300) --------------------------------------------------- 15- 38 REAR DRIVING MECHANISM (MXU 300) INSTALLATION ---- 15- 40...
  • Page 270 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 MXU 250 15-1...
  • Page 271 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 MXU 300 15-2...

  • Page 272: Service Information

    1.1 kgf-m (11 N-m, 8 lbf-ft) Left pivot lock nut (MXU 300) 11.8 kgf-m (118 N-m, 85 lbf-ft) Final gear case mounting bolt (MXU 300) 5.5 kgf-m (55 N-m, 40 lbf-ft) Final gear case cover bolt (MXU 300) 10-mm bolt:...

  • Page 273: Rear Wheel/Rear Wheel Hub

    REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 REAR WHEEL/REAR WHEEL REMOVAL AND INSPECTION Remove four nuts attaching the rear wheel hub of the both rear wheels, then remove the both rear wheels. Elevate the rear wheels by placing a suitable stand under the rear of frame.
  • Page 274 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Measure the wheel runout. Service Limit: Vertical: 2 mm (0.08 in) Lateral: 2 mm (0.08 in) Out of specification → Replace wheel. INSTALLATION Apply molybdenum disulfide grease to axle shaft spline end (out side), so the spline grove is filled with grease.

  • Page 275: Rear Axle/Axle Hub (Mxu 250)

    REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Install the rear wheel and tighten the four nuts. Torque: 4.5 kgf-m (45 Nm, 32 lbf-ft) Be sure the tapered side of the wheel nuts face the wheel rim. REAR AXLE/AXLE HUB (MXU Rear Axle Nuts...
  • Page 276 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Remove the rear brake disk. Rear Brake Disk Inspect the brake disk Cracks/damage → Replace. Inspect the brake disk splines. Wear/damage → Replace. Splines Drive Sprocket Cover Bolts Loosen the driven chain (refer to the “DRIVE CHAIN SLACK ADJUSTMENT”...
  • Page 277 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Driven Sprocket Remove the rear axle from right side. Tap the axle and with a rubber hammer, this will avoid damage the axle thread. Rear Axle REAR AXLE DISASSEMBLY 15-8...
  • Page 278 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Remove the driven sprocket clip at the rear axle and then remove the driven sprocket. Clip Remove the four nuts attaching the driven sprocket holder at the driven sprocket and then remove driven sprocket.
  • Page 279 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Inspect the driven sprocket holder splines. Wear/damage → Replace. Splines Inspect the rear axle. Scratched (excessively)/damage → Replace. Inspect the splines and threads of the rear axle Wear/damage → Replace. Measure the rear axle run out.
  • Page 280 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Bolts Remove the bolt at the rear caliper holder. Remove the two bolts attaching the rear axle hub at the rear fork. Bolt Collar Circlip Remove the circlip at the caliper holder and then remove the caliper holder and collar.
  • Page 281 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Remove the rear axle hub from right side. Rear Axle Hub Inspect rear axle hub. Bearings allow play in the axle hub or the bearing turns roughly → Replace. Dust seals is wear/damage → Replace.
  • Page 282 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Dust Seal Bearing Dust Seal REAR AXLE HUB ASSEMBLY Install the new bearing and dust seal by reversing the previous steps. Do not strike the center race or balls of the bearing. Contact should be made only with the outer race.
  • Page 283 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Tighten the two rear axle nuts (inner and outer). Note that the rear axle nuts are left threaded. Special tool: Nut wrench F010 Torque: 12 kgf-m (120 Nm, 86 lbf-ft) Adjust drive chain slack. (Refer to the “DRIVE CHAIN SLACK ADJUSTMENT”...

  • Page 284: Rear Shock Absorber

    REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 REAR SHOCK ABSORBER REMOVAL AND INSPECTION Support the vehicle with a support block to raise the rear wheels off the ground. Support the swingarm and remove the lower mounting bolt/nut. Remove the upper mounting bolt/nut and nut and the shock absorber.

  • Page 285: Swingarm (Mxu 250)

    REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 INSTALLATION Install the shock absorber and tightening the bolts/nuts. Torque: 4 kgf-m (40 Nm, 29 lbf-ft) Bolts/Nuts Pivot bolt SWINGARM (MXU 250) REMOVAL AND INSPECTION Place the machine on a level place. Elevate the rear wheels by placing a suitable stand under the rear of frame.
  • Page 286 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Check the swingarm side play by moving it from side to side. If side play noticeable, check the inner collar, bearing, bushing and thrust cover, or adjust the shim. Check the swingarm vertical movement by moving it up and down.
  • Page 287 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Pivot Shaft Remove the nut and pivot bolt, then remove rear swingarm and drive chain. Remove the four bolts from the lower guard and then remove the lower guard. Bolts Swingarm Remove the thrust covers.
  • Page 288 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Thrust Covers Inspect the swingarm. Crack/bend/damage → Replace. Roll the pivot bolt on a flat surface to inspect the pivot shaft. Bends → Replace. Do not attempt to straighten a bent bolt. Inspect the thrust covers, collar and bushes.
  • Page 289 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 INSTALLATION Reverse the “SWIMARM (MXU 250) REMOVAL AND INSPECTION” procedure. Apply grease onto the collar, bush, pivot bolt and thrust cover. Install the swingarm and drive chain. Install the pivot bolt and tightening the nut and pivot bolt.

  • Page 290: Rear Driving Mechanism (Mxu 300) Removal And Inspection

    REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 REAR DRIVING MECHANISM (MXU 300) REMOVAL AND INSPECTION Place the machine on a level place. Elevate the rear wheels by placing a suitable stand under the rear of frame. Support the machine securely so there is no danger of it falling over.
  • Page 291 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Joint Boot Loosen the joint boot band screw of the swingarm side. Remove the joint boot from the swingarm. Scerw (Swingarm side) Rear Shock Absorber Remove the rear shock absorber (page 15- 15). Remove the bolt and band, then disconnect the rear brake fluid hoses from the swingarm.
  • Page 292 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Pivot Adjusting Bolt Remove the swingarm pivot bolt cap. Remove the left pivot lock nut using the special tool. Special tool: Lock nut wrench F013 Remove the left pivot adjusting bolt. Lock Nut Spring Remove the swingarm, then take spring out from the swingarm.
  • Page 293 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Drive Shaft Disengage the universal joint from the drive shaft splines. Universal Joint Universal Joint UNIVERSAL JOINT INSPECTION: If the splines are damaged, check the pinion and universal joint splines also. Drive Shaft DRIVE SHAFT INSPECTION: Check the splines of the drive shaft wear or damage.
  • Page 294 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Remove the eight mounting bolts (front/left) and then remove the rear driving mechanism. Bolts Bolts Support the swingarm with a support block and place a rubber mat under the rear axle right side end.

  • Page 295: Final Drive Shim (Mxu 300) Adjustment/Final Gear

    If the gears do not turn smoothly or quietly, the gears and/or bearing may be damaged or faulty. Replace the final gear case assembly if necessary. FINAL DRIVE SHIM (MXU 300) ADJUSTMENT/FINAL GEAR CASE (MXU 300) DISASSEMBLY BACKLASH Hold the pinion gear with the special tool.
  • Page 296 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Remove the oil cap and a horizontal type dial indicator on the ring gear through the filler hole. Turn the ring gear back and forth to read backlash. Standard: 0.05 – 0.25 mm (0.002 – 0.01 in) Service limit: 0.4 mm (0.16 in)
  • Page 297 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Change the right side shim an equal thickness and opposite amount of what the left side shim was changed; if the left shim was replaced with a 0.03 mm (0.0012 in) thicker shim, replace the right shim with one that is 0.03 mm (0.0012 in) thinner.
  • Page 298 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Pry the cover at the prying point using a screwdriver. Prying Point Shim Shim Remove the case cover and right ring gear shim. Remove the ring gear and left ring gear shim. Cover Ring Gear...
  • Page 299 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Ring Gear Left Shim GEAR TOOTH CONTACT CHECK Clean sealing material off the mating surfaces of the gear case and cover, being careful not to damage them. Keep dust and dirt out of the case and cover.
  • Page 300 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Remove he oil cap. Rotate ring gear several turns in each direction. Check the gear tooth contact pattern through the oil filler hole. Incorrect: This will provide a contact pattern on the Contact at tooth top coated teeth of the gear.
  • Page 301 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Oil Seal PINION GEAR REMOVAL Check the oil seal for wear or damage; replace it if necessary. Remove the oil seal from the gear case. Lock Nut Remove the lock nut using the special tool.
  • Page 302 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 PINION GEAR BEARING AND SHIM REPLACEMENT Pull the pinion bearing from the shaft with a commercially available bearing puller. Remove the pinion shim. Install the shim and bearing onto the pinion Pinion Gear Bearing gear.
  • Page 303 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Bearing FINAL GEAR CASE BEARING REPLACEMENT CASE BEARING: Remove the oil seal. Drive the ring gear bearing out of the case. Oil Seal Bearing CASE COVER BEARING: Remove the oil seal. Drive the ring gear bearing out of the case cover.
  • Page 304 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Oil Seal Oil Seal Apply grease to new oil seal lips. Install each oil seal with the flat side facing out until it is flush with the case or cover. PINION NEEDLE BEARING Remove the pinion gear (page 15-32).

  • Page 305: Final Gear Case (Mxu 300) Assembly

    Apply grease to a new oil seal lips and install it into the gear case until it is fully seated. FINAL GEAR CASE (MXU 300) ASSEMBLY When the gear set, bearing, and/or gear case has been replaced, check the tooth...
  • Page 306 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Shim Shim Install the proper ring gear shims onto the ring gear and install them into the gear case. Apply liquid sealant to the mating surface of the case cover. Install the case cover over the gear case.

  • Page 307: Swingaem (Mxu300)

    DRIVING MECHANISM MXU 300/250 Make sure that the gear assembly rotates smoothly without binding. Dust Seal Bearing SWINGARM (MXU 300) SWINGARM INSPECTION/BEARING REPLACEMENT Inspect the dust seal for wear or damage. If any damages are found, replace them with new ones.
  • Page 308 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Remove the swingarm bearing race and bearing plate by using the special tool. Special tool: Bearing puller E037 The removed bearing and dust seal must be replaced with new ones. Bearing Plate/Bearing Race Install the new swingarm bearing race and its new plate to the swingarm by using the special tool.

  • Page 309: Rear Driving Mechanism (Mxu 300) Installation

    Pack 3 g (0.1 oz) of grease into bearing cavity. Bolts REAR DRIVING MECHANISM (MXU 300) INSTALLATION Apply grease to new O-ring and install it into the groove in the swingarm. Install the dust plate and tighten the three bolts securely.
  • Page 310 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Apply Grease Apply molybdenum disulfide grease to the center splines of the rear axle. Install the rear axle into the final gear case from left side until it is fully seated. Install the rear axle into the axle housing from swingarm right side and install final gear case.
  • Page 311 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Drive Shaft/Spring Set the drive shaft assembly into the swingarm, then secure drive shaft and spring onto the pinion gear shaft in the final gear case. Apply Gearse Pack 3 g (0.1 oz) of grease into each bearing cavity.
  • Page 312 REAR WHEEL/AXLE/SUSPENSION DRIVING MECHANISM MXU 300/250 Lock Nut Wrench Install the right pivot bolt and the left pivot adjusting bolt. Tighten the right pivot bolt to the specified torque. Actual: 11.8 kgf-m (118 N-m, 85 lbf-ft) Tighten the left pivot adjusting bolt to the specified torque.
  • Page 313 REAR WHEEL/AXLE/SUSPENSION/ DRIVING MECHANISM MXU 300/250 Apply molybdenum disulfide grease to the disk holder splines and the rear axle splines. Install the rear brake disk. Install the brake calipers (page 13-22). Install the rear wheel hubs and wheels (15- Disk...

  • Page 314: A.c. Generator

    . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 __________________________________________________________________________________ BATTER/CHARGING SYSTEM/ A.C. GENERATOR SERVICE INFORMATION------------------------------------------------ 16- 2 TROUBLESHOOTING----------------------------------------------------- 16- 3 BATTERY -------------------------------------------------------------------- 16- 4 CHARGING SYSTEM ----------------------------------------------------- 16- 7 REGULATOR/RECTIFIER------------------------------------------------ 16- 8 A.C. GENERATOR INSPECTION ---------------------------------------- 16- 9 16-0...
  • Page 315 . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 Fuse/Battery A.C. Generator Regulator/Rectifier CHARGING CIRCUIT 16-1...
  • Page 316 . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 SERVICE INFORMATIONN GENERAL INSTRUCTIONS The battery electrolyte (sulfuric acid) is poisonous and may seriously damage the skin and eyes. Avoid contact with skin, eyes, or clothing. In case of contact, flush with water and get prompt medical attention •...
  • Page 317 . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 TESTING INSTRUMENTS Electric tester TROUBLESHOOTING No power Intermittent power • Dead battery • Loose battery cable connection • Disconnected battery cable • Loose charging system connection • Fuse burned out • Loose connection or short circuit in lighting system •...
  • Page 318 . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 Seat BATTERY REMOVAL/INSTALLATION 1. Make sure the ignition switch is OFF. 2. Pull right the lock lever and pull up the seat at the rear. Lock Lever 3. ON ROAD: Hang license light holder (1), by...
  • Page 319 . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 5. Release the rings and remove the rubber band (6). 6. Shift the battery (7) and the terminal leads face you. 7. Disconnect the negative (-) terminal lead (8) from the battery first, then disconnect the positive (+) terminal lead (9).
  • Page 320 . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 BATTERY VOLTAGE (OPEN CIRCUIT VOLTAGE) INSPECTION Remove the seat. Disconnect the battery cables. Measure the voltage between the battery terminals. Fully charged : 13.1V Undercharged : 12.3V max Battery charging inspection must be performed with a voltmeter.

  • Page 321: Charging System

    . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 CHARGING SYSTEM CURRENT LEAKAGE TEST Remove the seat (see page 2-3). Turn the ignition switch “OFF”, and disconnect the negative (-) cable from the battery. Connect the ammeter (+) probe to the negative (-) cable and the ammeter (-) probe to the battery (-) terminal.
  • Page 322 . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 Regulator/Rectifier Connectors REGULATOR/RECTIFIER INSPECTION Remove the right side cover. ( Refer to chapter 2 ) Remove the regulator/rectifier wire connectors. Check the continuity between the wire terminals. Lock Nut Regulator/Rectifier Normal Direction: Continuity...
  • Page 323 . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 A.C. GENERATOR INSPECTION This test can be made without removing the stator from the engine. Disconnect the A.C. generator connector. Check the continuity between the yellow wires and ground. There should be continuity between the yellow wires and no continuity between each yellow wire and ground.
  • Page 324 . BATTERY/CHARGING SYSTEM/ A.C. GENERATOR MXU 300/250 Flywheel Hold the flywheel with a flywheel holder and remove flywheel nut and wash. Special tool: Flywheel holder E021 Flywheel Holder Flywheel Puller Remove the flywheel with a flywheel puller. Special tool: Flywheel puller...
  • Page 325 . IGNITION SYSTEM MXU 300/250 __________________________________________________________________________________ IGNITION SYSTEM SERVICE INFORMATION------------------------------------------------ 17- 2 TROUBLESHOOTING----------------------------------------------------- 17- 3 IGNITION UNIT /CHANGE GEAR CONTROL INSPECTION----- 17- 4 IGNITION COIL INSPECTION------------------------------------------- 17- 6 PULSER COIL --------------------------------------------------------------- 17- 7 17-0...
  • Page 326 . IGNITION SYSTEM MXU 300/250 Ignition Coil Ignition Unit/Change Gear Control A.C. Generator/ Pulser Coil IGNITION CIRCUIT (ON ROAD) 17-1...
  • Page 327 . IGNITION SYSTEM MXU 300/250 IGNITION CIRCUIT (OFF ROAD) SERVICE INFORMATION GENERAL INSTRUCTIONS • Check the ignition system according to the sequence specified in the Troubleshooting. • The ignition system adopts ignition unit, change gear control and the ignition timing cannot be adjusted.
  • Page 328 . IGNITION SYSTEM MXU 300/250 SPECIFICATIONS Item Standard Spark plug Standard type DPR7EA-9 Spark plug gap 0.6～0.7mm “F” mark Ignition timing 5º±1ºBTDC/1000RPM Full advance Primary coil 3.4～4.1Ω Ignition coil resistance (20 ) Secondary without plug cap 14.45KΩ coil with plug cap 19.8KΩ...
  • Page 329 . IGNITION SYSTEM MXU 300/250 Change Gear Control IGNITION UNIT /CHANGE GEAR CONTROL INSPECTION Remove the seat. (Refer to the chapter 2) Disconnect the ignition unit coupler and remove the ignition unit. Disconnect the change gear control coupler and remove the change gear control.

  • Page 330: Ignition System

    . IGNITION SYSTEM MXU 300/250 Test the ignition unit using the ignition unit tester. CDI Tester Ignition Coil Operate the ignition unit tester by Spark following the manufacturer‘s Window instructions. Connect the special connector to the ignition unit coupler and ignition unit tester.
  • Page 331 . IGNITION SYSTEM MXU 300/250 IGNITION COIL INSPECTION CONTINUITY TEST Remove the front fender. (Refer to the chapter 2) Remove the spark plug cap. (Refer to the chapter 6) Disconnect the ignition coil wires. This test is to inspect the continuity of ignition coil.
  • Page 332 . IGNITION SYSTEM MXU 300/250 Measure the spark plug cap resistance. Remove the spark plug cap and measure the spark plug resistance. Resistance: 4.2～5.2KΩ/20◦C Measure the resistance in the XKΩ range of the electric tester. PERFORMANCE TEST CDI Tester Ignition Coil Test the performance with a ignition unit tester.

  • Page 333: Starting System

    . STARTING SYSTEM MXU 300/250 __________________________________________________________________________________ STARTING SYSTEM SERVICE INFORMATION------------------------------------------------ 18- 2 TROUBLESHOOTING----------------------------------------------------- 18- 2 STARTER MOTOR --------------------------------------------------------- 18- 3 STARTER RELAY---------------------------------------------------------- 18- 7 STARTER CLUTCH-------------------------------------------------------- 18- 8 RECOIL STARTER --------------------------------------------------------- 18-10 18-0...
  • Page 334 . STARTING SYSTEM MXU 300/250 Starter Button/ Stop Switches Fuse/Battery/Starter Relay Starter Motor STARTING CIRCUIT 18-1...

  • Page 335: Starting System

    . STARTING SYSTEM MXU 300/250 SERVICE INFORMATION GENERAL INSTRUCTIONS • The removal of starter motor can be accomplished with the engine installed. TROUBLESHOOTING Starter motor won‘t turn Lack of power • Fuse burned out • Weak battery • Weak battery •...

  • Page 336: Starter Motor

    . STARTING SYSTEM MXU 300/250 Rubber Jacket Bolts STARTER MOTOR REMOVAL Before removing the starter motor, turn the ignition switch OFF and remove the battery ground. Then, turn on the ignition switch and push the starter button to see if the starter motor operates properly.
  • Page 337 . STARTING SYSTEM MXU 300/250 Check for continuity between pairs of the commutator segments and there should be continuity. Also, make a continuity check between individual commutator segments and the armature shaft. There should be no continuity. STARTER MOTOR CASE...
  • Page 338 . STARTING SYSTEM MXU 300/250 Check for continuity between the brushes. If there is continuity, replace with new ones. Bearing Check if the needle bearing in the front cover turns freely and has no excessive play. Replace if necessary. Check the dust seal for wear or damage.
  • Page 339 . STARTING SYSTEM MXU 300/250 Groove Install a new O-ring to the front cover. Install the starter motor case, aligning the tab on the motor case with the groove on the front cover. Tighten the starter motor case screws. When assembling the front cover and motor case, slightly press down the armature shaft to assemble them.

  • Page 340: Starter Relay

    . STARTING SYSTEM MXU 300/250 Starter Relay STARTER RELAY INSPECTION Remove the seat. (Refer to the chapter 2) Turn the ignition switch ON and the starter relay is normal if you hear a click when the starter button is depressed.

  • Page 341: Starter Clutch

    . STARTING SYSTEM MXU 300/250 STARTER CLUTCH REMOVAL Remove the right crankcase cover. (Refer to the “WATER PUMP SHAFT REMOVAL” section in the chapter 12) Remove the flywheel. (Refer to the “A.C. GENERATOR/FLYWHEEL REMOVAL” section in the chapter 16 Inspect the starter one-way clutch for wear or damage.
  • Page 342 . STARTING SYSTEM MXU 300/250 Starter Idle Gear Shaft Remove the starter idle gear and shaft. Starter Idle Gear Starter Idle Gear Inspect the starter idle gear and shaft for wear or damage. Starter Idle Gear Shaft INSTALLATION Reverse the “REMOVAL” procedures.

  • Page 343: Recoil Starter

    . STARTING SYSTEM MXU 300/250 Recoil Starter RECOIL STARTER Refer to the chapter 9 to remove recoil starter. Do not disassembly that the recoil starter would not be assembly. ROPE REPLACE Insert the rope into the hook part of the friction plate, reel the rope clockwise five times with the rope, then cut the rope.
  • Page 344 . STARTING SYSTEM MXU 300/250 Washer Insert the rope into recoil starter grip and washer. Reinstall the cap. Pull the rope and check that the ratchet is pushed out Refer to the chapter 9 to remove ratchet. Inspect the ratchet splines.

  • Page 345: Lights/Switches

    . LIGHTS/SWITCHES MXU 300/250 __________________________________________________________________________________ LIGHTS/SWITHCES SERVICE INFORMATION------------------------------------------------ 19- 1 BULBS REMOVAL--------------------------------------------------------- 19- 2 HORN (ON ROAD) --------------------------------------------------------- 19- 4 IGNITION SWITCH -------------------------------------------------------- 19- 5 HANDLEBAR SWITCH --------------------------------------------------- 19- 5 NEUTRAL/REVESE SWITCH-------------------------------------------- 19- 7 19-0...

  • Page 346: Service Information

    . LIGHTS/SWITCHES MXU 300/250 SERVICE INFORMATION ● A continuity test can be made with the switches installed on the vehicle. ● All plastic connectors have locking tabs that must be released before disconnecting, and must be aligned when reconnecting. ● To isolate an electrical failure, check the continuity of the electrical path through the part. A continuity check can usually be made without removing the pat from the vehicle.

  • Page 347: Bulbs Removal

    . LIGHTS/SWITCHES MXU 300/250 Rubber Boot BULBS REMOVAL HEADLIGHT Remove the front fender. (See page 2-8) Remove the rubber boot from the headlight case. Disconnect the headlight wire connector. Headlight Connector Lock Clip Lock Clips Relax the lock clips to remove the bulb and replace with a new one.
  • Page 348 . LIGHTS/SWITCHES MXU 300/250 Bulb TAIL/BRAKE LIGHT Bulb Socket Remove the bulb socket by turning it counterclockwise. Remove the bulb. Install the bulb in the reverse order of removal. Rubber Boot TURN SIGNAL LIGHT (ON ROAD) FRONT Remove the rubber boot from the turn signal light case.

  • Page 349: Horn (On Road)

    . LIGHTS/SWITCHES MXU 300/250 Bulb Socket REAR Remove the bulb socket by turning it counterclockwise. Remove the bulb. Install the bulb in the reverse order of removal. Bulb LICENCE LIGHT BULB (ON ROAD) Remove the two screws and licence light cover.

  • Page 350: Ignition Switch

    . LIGHTS/SWITCHES MXU 300/250 IGNITION SWITCH INSPECTION Disconnect the ignition switch connectors. (Refer to the “HANDLEBAR COVER REMOVAL” section in chapter 2.) Check for continuity between the switch side connector terminals in each switch position. Continuity should exist between the color...
  • Page 351 . LIGHTS/SWITCHES MXU 300/250 Hazard Switch (ON ROAD) Winker Switch Horn Switch Light Switch Start Switch Dimmer Switch (OFF ROAD) Start Switch Kill Switch Pass Switch 19-6...
  • Page 352 . LIGHTS/SWITCHES MXU 300/250 NEUTRAL/REVERSE SWITCHES INSPECTION Disconnect the neutral/reverse switch wire connector. (See page 6-4 or 6-10) Check for continuity between the switch side connector terminal and engine ground. NEUTRAL SWITCH There should be continuity with the transmission in neutral and no continuity with it in any gear except neutral.

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