KYMCO MXU 50 REVERSE Service Manual
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KYMCO MXU 50 REVERSE Service Manual

Mxu 50 reverse; mxu 50; mx'er 50 kymco
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See also: Owner's Manual
By KWANG YANG Motor Co., Ltd.
First Edition, Jan 2006
All rights reserved. Any reproduction or
unauthorized use without the written permission of
KWANG YANG Motor Co., Ltd.
is expressly prohibited.
T100LB10DE

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  • Page 1 By KWANG YANG Motor Co., Ltd. First Edition, Jan 2006 All rights reserved. Any reproduction or unauthorized use without the written permission of KWANG YANG Motor Co., Ltd. is expressly prohibited. T100LB10DE...

  • Page 2: Table Of Contents

    PREFACE This Service Manual describes the TABLE OF CONTENTS technical features and servicing procedures for the KYMCO MXU 50 GENERAL INFORMATION REVERSE/MXU 50/MX’ER 50. FRAME COVERS/EXHAUST MUFFLER Section 1 contains the precautions for INSPECTION/ADJUSTMENT all operations stated in this manual.
  • Page 3 SPECIAL TOOLS ----------------------------------------------------------- 1-14 LUBRICATION POINTS -------------------------------------------------- 1-14 CABLE & HARNESS ROUTING (MX’ER 50) ------------------------ 1-17 CABLE & HARNESS ROUTING (MXU 50 REVERSE/MXU 50) - 1-21 WIRING DIAGRAM (MX’ER 50 ON ROAD) ------------------------- 1-26 WIRING DIAGRAM (MX’ER 50 OFF ROAD) ------------------------ 1-27...

  • Page 4: General Information

    . GENERAL INFORMATION ATV 50 SERIAL NUMBER Location of Frame Serial Number Location of Engine Serial Number...

  • Page 5: General Information

    . GENERAL INFORMATION ATV 50 SPECIFICATIONS Air cleaner type Sponge Model No. LA10 Fuel capacity 8.1 liters Name MX’ER 50 Type Main jet No. Overall length 1685 mm (67.4 in) φ14 mm (φ0.56 in) Venturi dia Overall width 980 mm (39.2 in) Throttle type Valve piston Overall height...
  • Page 6 . GENERAL INFORMATION ATV 50 Model No. LB10 Air cleaner type Sponge Fuel capacity 8.1 liters Name MXU 50 Type Overall length 1775 mm (71 in) Main jet No. φ14 mm (φ0.56 in) Venturi dia Overall width 950 mm (38 in) Throttle type Valve piston Overall height...
  • Page 7 . GENERAL INFORMATION ATV 50 Model No. LB10 Air cleaner type Sponge Fuel capacity 8.1 liters Name MXU 50 REVERSE Type Overall length 1786 mm (71 in) Main jet No. φ14 mm (φ0.56 in) Venturi dia Overall width 958 mm (38 in)

  • Page 8: Service Precautions

    . GENERAL INFORMATION ATV 50 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 9 . GENERAL INFORMATION ATV 50 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. Disconnect the battery negative (-) terminal before operation.
  • Page 10 . GENERAL INFORMATION ATV 50 If the fuse is burned out, find the cause and repair it. Replace it with a new one according to the specified capacity. Confirm 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 11 . GENERAL INFORMATION ATV 50 The connector shall be inserted completely. Snapping! If the double connector has a lock, lock it 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 12 . GENERAL INFORMATION ATV 50 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 13 . GENERAL INFORMATION ATV 50 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. When rubber protecting cover is used to protect the wire harnesses, it shall be installed securely.
  • Page 14 . GENERAL INFORMATION ATV 50 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 15 . GENERAL INFORMATION ATV 50 Symbols: The following symbols represent the servicing methods and cautions included in this service manual. : Apply engine oil to the specified points. (Use Engine Oil designated engine oil for lubrication.) Grease : Apply grease for lubrication. Special : Caution : Warning...

  • Page 16: Torque Values

    3.8 (38, 27) Oil check/filler bolt (MXU 50/MX’ER 50) 1.2 (12, 9) Oil drain plug 2 (20, 15) Oil filler bolt (MXU 50 REVERSE) 2 (20, 15) Exhaust muffler joint lock nut NC6mm 1.2 (12, 9) Exhaust muffler lock bolt BF8X35 3.3 (33, 24)

  • Page 17: Special Tools

    . GENERAL INFORMATION ATV 50 Torque Thread dia.(mm) Remarks kgf-m (N-m, Item Q‘ty lbf-ft) Front shock absorber lower mount bolt 4 (40, 29) Rear fork axle 7 (70, 50) Rear hub nut 7 (70, 50) Rear wheel shaft nut 12 (120, 86) Rear engine bracket up bolt 4 (40, 29) Rear engine bracket bolt...
  • Page 18 GENERAL INFORMATION ATV 50 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 motorcycle. Rear Brake Cable Front Brake Cable Throttle Cable...
  • Page 19 . GENERAL INFORMATION ATV 50 Swing arm Thrust Cover Rear Brake Cam/ Axle Hub Collar/Oil Seal/Bearing Sprocket hub/Rear Axle Hub Collar/Oil Seal/Bearing Driven Sprocket 1-16...

  • Page 20: Cable & Harness Routing (Mx'er 50)

    GENERAL INFORMATION ATV 50 CABLE & HARNESS ROUTING (MX’ER 50) Rear Brake Cable Throttle Cable Front Brake Cable Handlebar Switch Lead A.C.G Wire Starter Motor Wire Auto Bystarter Left Front Brake Cable Right Front Brake Cable 1-17...
  • Page 21 . GENERAL INFORMATION ATV 50 Fuel Filter Fuel Tube Ignition Coil Wire Throttle Cable Oil Meter Wire Left Front Brake Cable Right Front Brake Cable Rear Brake Cable 1-18...
  • Page 22 GENERAL INFORMATION ATV 50 Ignition Coil Wire Harness Rectifier/Regulator Resistor Oil Tube Right Front Brake Cable 1-19...
  • Page 23 . GENERAL INFORMATION ATV 50 Main Switch Rear Brake Cable Breather Hose Oil Meter Wire Battery Negative Cable Positive Cable Starter Relay Fuse CDI Unit 1-20...

  • Page 24: Cable & Harness Routing (Mxu 50 Reverse/Mxu 50)

    GENERAL INFORMATION ATV 50 CABLE & HARNESS ROUTING (MXU 50 REVERSE/MXU 50) Fuel Tank Breather Hose Throttle Cable Rear Brake Light Switch Wire Front Brake Cable Rear Brake Fluid Hose Front Brake Light Switch Wire Instrument Connector Right Headlight/ Handlebar Switch Connectors...
  • Page 25 . GENERAL INFORMATION ATV 50 Inlet Hose Ignition Coil Oil Inlet Hose Fuel Valve Auto Choke Connector Air Cleaner Throttle Cables Spark Plug Cap Neutral Switch Wire (MXU 50 REVERSE) Rear Brake Hose Starter Motor Connector 1-22...
  • Page 26 Ignition Coil Wire Hazard Unit Harness Wire Headlight Control Unit Throttle Cable Oil Outlet Hose Starter Motor Cable Fuel Drain Hose ACG Wire Ignition Coil Cable Transmission Case Breather Hose (MXU 50 REVERSE) Neutral Switch Wire (MXU 50 REVERSE) 1-23...
  • Page 27 . GENERAL INFORMATION ATV 50 Pulser Connector Oil Level Connectors ACG Connector Fuel Unit Connectors ACG Connector Harness Wire Rectifier/Regulator Starter Motor Rectifier/Regulator Connector Transmission Case Breather Hose Carburetor Drain Hose (MXU 50 REVERSE) Speedometer wire 1-24...
  • Page 28 GENERAL INFORMATION ATV 50 Tail Light/Brake light Wire Speed Sensor Rear Right Turn Signal Light Connectors Negative Cable Rear Left Turn Signal Light Positive Cable Speedometer Wire Rear Brake Hose Start Relay Fuse Box Harness Wire 1-25...

  • Page 29: Wiring Diagram (Mx'er 50 On Road)

    . GENERAL INFORMATION ATV 50 WIRING DIAGRAM (MX’ER 50) (ON ROAD) 1-26...

  • Page 30: Wiring Diagram (Mx'er 50 Off Road)

    GENERAL INFORMATION ATV 50 WIRING DIAGRAM (MX’ER 50) (OFF ROAD) 1-27...

  • Page 31: Wiring Diagram (Mxu 50 On Road)

    . GENERAL INFORMATION ATV 50 WIRING DIAGRAM (MXU 50) (ON ROAD) 1-28...

  • Page 32: Wiring Diagram (Mxu 50 Reverse On Road)

    GENERAL INFORMATION ATV 50 WIRING DIAGRAM (MXU 50 REVERSE) (ON ROAD) 1-29...

  • Page 33: Troubleshooting

    . GENERAL INFORMATION ATV 50 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 float valve Fuel reaches Fuel does not Clogged charcoal canister carburetor reach carburetor Clogged fuel filter...
  • Page 34 GENERAL INFORMATION ATV 50 ENGINE STOPS IMMEDIATELY AFTER IT STARTS Inspection/Adjustment Symptom Probable Cause Check if fuel reaches carburetor by loosening drain screw. Empty fuel tank Clogged float valve Fuel reaches Fuel does not Clogged charcoal canister carburetor reach carburetor Clogged fuel filter Faulty auto fuel valve Remove spark plug and...
  • Page 35 . GENERAL INFORMATION ATV 50 Inspection/Adjustment Probable Cause Symptom Check carburetor gasket for air leaks. Carburetor not securely tightened No air leak Air leaks Faulty intake manifold gasket Deformed or broken carburetor O-ring Remove auto bystarter connecting wire and check if bypass fuel line is clogged.
  • Page 36 GENERAL INFORMATION ATV 50 ENGINE LACKS POWER Inspection/Adjustment Symptom Probable Cause Start engine and accelerate lightly for observation. Clogged air cleaner Engine speed does Clogged fuel filter Engine speed not increase Clogged exhaust muffler increases sufficiently Faulty auto bystarter Faulty charcoal canister Check ignition timing (using a timing light).
  • Page 37 . GENERAL INFORMATION ATV 50 POOR PERFORMANCE (ESPECIALLY AT IDLE AND LOW SPEEDS) Inspection/Adjustment Symptom Probable Cause Check ignition timing. Faulty CDI unit Incorrect timing Correct timing Faulty A.C. generator Check carburetor air screw adjustment. Mixture too rich (turn screw Correctly adjusted Incorrectly adjusted out)
  • Page 38 GENERAL INFORMATION ATV 50 POOR PERFORMANCE (AT HIGH SPEED) Inspection/Adjustment Symptom Probable Cause Check ignition timing. Faulty CDI unit Correct timing Incorrect timing Loose A.C.G. stator Faulty A.C. generator Check auto fuel valve for fuel supply. Empty fuel tank Fuel flows freely Fuel flow restricted Clogged fuel tube or filter Clogged charcoal canister...
  • Page 39 . GENERAL INFORMATION ATV 50 CLUTCH, DRIVE AND DRIVEN PULLEYS Symptom Probable Cause Worn or slipping drive belt Broken ramp plate Broken driven face spring Engine starts but motor- Separated clutch lining cycle does not move Damaged driven pulley shaft splines Damaged final gear Seized final gear Motorcycle creeps or...
  • Page 40 GENERAL INFORMATION ATV 50 POOR SUSPENSION PERFORMANCE Symptom Probable Cause (Front and rear tire pressures are normal) Weak shock spring Suspension is too soft Excessive load Shock damper oil leaking Bent fork tube or shock rod Suspension is too hard Fork slider and tube binding Fork tube and spring binding Suspension is noisy...
  • Page 41 . GENERAL INFORMATION ATV 50 OIL METER 1. Motor oil indicator light does not come on when there is no motor oil (Ignition switch ON) Inspection/Adjustment Symptom Probable Cause Check battery circuit by operating turn signals. Burned out fuse Weak or dead battery Signals dim, remain Signals operate Faulty ignition switch...
  • Page 42 GENERAL INFORMATION ATV 50 FUEL GAUGE 1. Pointer does not register correctly (Ignition switch ON) Inspection/Adjustment Symptom Probable Cause Check battery circuit by operating turn signals. Burned out fuse Weak or dead battery Signals operate Signals dim, remain Faulty ignition switch properly on or don‘t operate Loose or disconnected...
  • Page 43 . GENERAL INFORMATION ATV 50 STARTER MOTOR 1. Starter motor won‘t turn Symptom Inspection/Adjustment Probable Cause Check operation of Burned out fuse stop switch by Weak or dead battery applying brake. Faulty stop switch Stoplight does not Stoplight comes on Loose or disconnected come on connector...
  • Page 44 FRAME COVERS (MX’ER 50) ------------------------------------------- 2- 3 HEADLIGHT REMOVAL (MX’ER 50) --------------------------------- 2- 5 FASTENER REMOVAL -------------------------------------------------- 2- 7 FRAME COVERS (MXU 50 REVERSE/MXU 50) -------------------- 2- 8 EXHAUST MUFFLER REMOVAL (MX’ER 50)---------------------- 2- 15 EXHAUST MUFFLER REMOVAL (MXU 50 REVERSE/MXU 50) ------------------------------------------- 2- 16...

  • Page 45: Service Information

    . FRAME COVERS/EXHAUST MUFFLER ATV 50 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. TORQUE VALUES Exhaust muffler lock bolt 3.3 kgf-m (33 N-m, 24 lbf-ft)
  • Page 46 . FRAME COVERS/EXHAUST MUFFLER ATV 50 MX’ER 50...

  • Page 47: Frame Covers (Mx'er 50)

    . FRAME COVERS/EXHAUST MUFFLER ATV 50 Lever Seat FRAME COVERS (MX’ER 50) SEAT REMOVAL Pull the lever backward, then pull up the seat at the rear. Remove the seat. Screws Bolt LEFT AND RIGHT REAR FENDER REMOVAL Remove seven screws and two bolts attaching the left rear fender.

  • Page 48: Frame Covers/Exhaust Muffler

    . FRAME COVERS/EXHAUST MUFFLER ATV 50 Front Cover FRONT COVERS REMOVAL Remove the two screws on the front cover. Screws Remove the left and right front fender under bolt. Remove the front cover. Bolts Right Front Cover FRONT FENDER REMOVAL Remove screws attaching the left and right front fender.

  • Page 49: Headlight Removal (Mx'er 50)

    . FRAME COVERS/EXHAUST MUFFLER ATV 50 FLOOR BOARD COVER REMOVAL Remove the four bolts on the floorboard cover. Remove the floorboard cover. Bolts Floor Board HEADLIGHT REMOVAL (MX’ER 50) Remove the headlight connector wire. Remove the two bolts on the headlight. Bolts...
  • Page 50 . FRAME COVERS/EXHAUST MUFFLER ATV 50 MXU 50 REVERSE/MXU 50...

  • Page 51: Fastener Removal

    . FRAME COVERS/EXHAUST MUFFLER ATV 50 FASTENER REMOVAL AND REINSTALLATION REMOVAL Depress the head of fastener center piece . Pull out the fastener. INSTALLATION Let the center piece stick out toward the head so that the pawls close. Insert the fastener into the installation hole. To prevent the pawl from damage, insert the fastener all the way into the...

  • Page 52: Frame Covers (Mxu 50 Reverse/Mxu 50)

    . FRAME COVERS/EXHAUST MUFFLER ATV 50 FRAME COVERS (MXU 50 REVERSE/MXU 50) SEAT REMOVAL Pull the lever (1) backward, then pull up the seat at the rear. Remove the 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 53 . FRAME COVERS/EXHAUST MUFFLER ATV 50 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 FRONT CARRIER Right/Left Signal Light Connectors REMOVAL/INSTALLATION Remove front cargo rack (see page 2-8).
  • Page 54 . FRAME COVERS/EXHAUST MUFFLER ATV 50 Bolts REAR CARGO RACK REMOVAL/INSTALLATION Remove the two bolts under the rear fender. Mounting Bolts Remove the two mounting bolts and two mounting nuts from the rear cargo rack right/left side under the rear fender. Installation is in the reverse order of removal.
  • Page 55 . FRAME COVERS/EXHAUST MUFFLER ATV 50 Fasteners Fasteners Remove 9 fasteners, 4 mounting bolts and the left footboard. During removal, do not pull the joint claws forcedly to avoid damage. Installation is in the reverse order of removal. Mounting Bolts Bolts Fastener RIGHT/LEFT SIDE COVER...
  • Page 56 . FRAME COVERS/EXHAUST MUFFLER ATV 50 FRONT CENTER COVER Screws REMOVAL/INSTALLATION Remove the front cargo rack (see page 2-8). Remove the two screws on the front cover, two screws under the front cover and front center cover. During removal, do not pull the joint claws forcedly to avoid damage.

  • Page 57: (Mxu 50 Reverse/Mxu 50)

    Fuel Tank Cap Nuts Installation is in the reverse order of removal. Drive Select Lever Grip MXU 50 REVERSE: Remove the bolt and then remove the drive select lever grip. Bolt FRONT FENDER REMOVAL/INSTALLATION Remove front carrier (see page 2-9), front...
  • Page 58 . FRAME COVERS/EXHAUST MUFFLER ATV 50 Bolt REAR FENDER REMOVAL/INSTALLATION Remove seat(see page 2-8), battery(see page 15-5 ), rear cargo rack (see page 2-10) and right/left footboard (see page 2-10). Remove one bolt and one nut, then remove the oil tank. Bolts Remove the three bolts from the rear fender.
  • Page 59 . FRAME COVERS/EXHAUST MUFFLER ATV 50 Nuts Nuts EXHAUST MUFFLER (MX’ER REMOVAL Remove the two nuts attaching the exhaust muffler. Remove the two nuts attaching the exhaust pipe. Muffler Remove the exhaust muffler lock bolts. Remove the exhaust muffler and them remove exhaust pipe.
  • Page 60 . FRAME COVERS/EXHAUST MUFFLER ATV 50 EXHAUST MUFFLER (MXU 50 Nuts REVERSE/MXU 50) REMOVAL Remove the two nuts attaching the exhaust pipe and cylinder head. Remove the two bolts attaching the exhaust muffler, then remove the exhaust muffler. Bolt Bolt Inspect the gasket.
  • Page 61 . INSPECTION/ADJUSTMENT ATV 50 __________________________________________________________________________________ INSPECTION/ADJUSTMENT SERVICE INFORMATION------------------------------------------------ 3- 1 MAINTENANCE SCHEDULE-------------------------------------------- 3- 2 FUEL LINE/THROTTLE OPERATION/AIR CLEANER ------------ 3- 3 SPARK PLUG/LUBRICATION SYSTEM ------------------------------ 3- 5 CARBURETOR IDLE SPEED -------------------------------------------- 3- 7 CYLINDER COMPRESSION/FINAL REDUCTION GEAR OIL --- 3- 8 DRIVE BELT/BRAKE SHOE/BRAKE SYSTEM --------------------- 3-10 HEADLIGHT AIM ---------------------------------------------------------- 3-12 STEERING SYSTEM INSPECTION------------------------------------- 3-13...

  • Page 62: Inspection/Adjustment

    At disassembly : 0.12 liter (0.11 lmp qt, 0.13 Us qt) At change : 0.09 liter (0.08 lmp qt, 0.1 Us qt) Gear oil capacity (MXU 50 REVERSE): At disassembly : 0.3 liter (0.26 lmp qt, 0.32 Us qt) At change : 0.25 liter (0.22 lmp qt, 0.26 Us qt)

  • Page 63: Maintenance Schedule

    This information applies to vehicles already in service as well as new vehicles that are being prepared for sale. All service technicians should be familiar with this entire chapter. • In the interest of safety, we recommend these items should be serviced only by an authorized KYMCO motorcycle dealer.

  • Page 64: Fuel Line/Throttle Operation/Air Cleaner

    . INSPECTION/ADJUSTMENT ATV 50 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 tube Fuel Filter THROTTLE OPERATION Check the throttle to swing for smooth movement.
  • Page 65 . INSPECTION/ADJUSTMENT ATV 50 CLEAN AIR FILTER ELEMENT Wash the element gently, but thoroughly 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 66: Spark Plug/Lubrication System

    . INSPECTION/ADJUSTMENT ATV 50 SPARK PLUG Remove the spark plug Check the spark plug for wear and fouling deposits. Clean any fouling deposits with a spark plug cleaner or a wire brush. Specified Spark Plug: NGK-BR8HAS Gap, Wear, and Fouling Deposits Measure the spark plug gap.
  • Page 67 . INSPECTION/ADJUSTMENT ATV 50 Clean the oil filter screen with compressed Filter Screen air. Install the oil filter in the reverse order of removal and fill the oil tank with specified oil up to the proper level. Bleed air from the oil pump and oil lines. •...

  • Page 68: Carburetor Idle Speed

    When the engine is running at the specified rpm, the ignition timing is correct if the “F” mark on the flywheel aligns with the index mark on the crankcase within ±1.5°. Ignition Timing: MX’ER 50: 22°±1.5°BTDC/2000rpm MXU 50 REVERSE/MXU 50: 13.5°±1.5°BTDC/1500rpm “F” Mark...

  • Page 69: Cylinder Compression/Final Reduction Gear Oil

    . INSPECTION/ADJUSTMENT ATV 50 CYLINDER COMPRESSION Warm up the engine before compression test. Remove the spark plug. Insert a compression gauge. Open the throttle valve fully and push the starter button to test the compression. Compression: 1200kPa (12kgf/cm²,170psi) If the compression is low, check for the following: - Leaky valves - Valve clearance too small...
  • Page 70 Oil Drain Bolt/ Sealing Washer Oil Capacity: MXU 50/MX’ER 50 Oil Filler Bolt At disassembly: MXU 50 REVERSE 0.12 liter (0.11 lmp qt,0.13 Us qt) At change: 0.09 liter (0.08 lmp qt,0.1 Us qt) MXU 50 REVERSE At disassembly: 0.3 liter (0.26 lmp qt,0.32 Us qt) At change: 0.25 liter (0.22 lmp qt,0.26 Us qt)

  • Page 71: Drive Belt/Brake Shoe/Brake System

    . INSPECTION/ADJUSTMENT ATV 50 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: 16.5mm (0.7 in) Replace the drive belt if out of specification. Drive Belt Wear Indicator BRAKE SHOE Replace the brake shoes if the arrow on the...
  • Page 72 . INSPECTION/ADJUSTMENT ATV 50 Adjusters Adjust brake lever free play: Loosen the lock nuts. Turn the adjusters in or out until the specified free play is obtained. Turning adjusters in that the free play is increased. Turning adjusters out that the free play is decreased.

  • Page 73: Inspection/Adjustment

    Adjust the headlight aim by turning the headlight aim adjusting screw. Adjusting Screw Adjust Screws MXU 50 REVERSE/MXU 50: Turn the ignition switch ON and start the engine. Turn on the headlight switch. Adjust the headlight aim by turning the headlight aim adjusting screws.

  • Page 74: Steering System Inspection

    . INSPECTION/ADJUSTMENT ATV 50 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 Check the tie-rod ends Turn the handlebar to the left and/or right until it stops completely, then slightly move...

  • Page 75: Toe-In Adjustment

    . INSPECTION/ADJUSTMENT ATV 50 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. Fix the handlebar straight ahead.

  • Page 76: Wheels/Tires

    Front Axle Nut Front/Rear (1 Rider) MX’ER 50 0.33 kgf/cm² (33 kPa, 4.7 psi) MXU 50 0.28 kgf/cm² (28 kPa, 3.9 psi) TIRE SIZE MXU 50 REVERSE/MXU50: Front: 21*7-10 Rear: 22*10-10 Rear Axle Nut MX’ER 50: Front: 20*7-8 Rear: 22*10-8 Check the front axle nut for looseness.

  • Page 77: Drive Chain Slack Adjustment

    . INSPECTION/ADJUSTMENT ATV 50 Inspect the wheel. Replace if damage or bends Always balance the wheel when a tire or wheel has been changed or replaced. • Never attempt even small repairs to the wheel. • Ride conservatively after installing a tire to allow it to seat itself properly on the rim.
  • Page 78 . INSPECTION/ADJUSTMENT ATV 50 Adjuster Turn the adjuster in or out until the specified slack is obtained. Turn in: Slack is increased. Turn out: Slack is decreased. Tighten four bolts attaching rear axle hub to Bolts the specification. While pushing up or down on the chain to zero slack.

  • Page 79: Cable Inspection And Lubrication

    . INSPECTION/ADJUSTMENT ATV 50 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. Check the cable operation.
  • Page 80 . LUBRICATION SYSTEM ATV 50 __________________________________________________________________________________ LUBRICATION SYSTEM SERVICE INFORMATION ..............4-2 TROUBLESHOOTING ............... 4-2 OIL PUMP REMOVAL............... 4-3 OIL PUMP INSPECTION ..............4-3 OIL PUMP INSTALLATION ............. 4-4 OIL PUMP BLEEDING............... 4-5 OIL TANK ................... 4-6...
  • Page 81 . LUBRICATION SYSTEM ATV 50 LUBRICATION SYSTEM...

  • Page 82: Service Information

    . LUBRICATION SYSTEM ATV 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • Use care when removing and installing the oil pump not to allow dust and dirt to enter the engine and oil line. • Do not attempt to disassemble the oil pump. •...

  • Page 83: Oil Pump Removal

    . LUBRICATION SYSTEM ATV 50 Oil Pump Oil Outlet Line OIL PUMP REMOVAL Do not allow foreign matters to enter the crankcase. Before removing the oil pump, clean the oil pump and crankcase surfaces. Disconnect the oil pump control cable from the pump body.

  • Page 84: Lubrication System

    . LUBRICATION SYSTEM ATV 50 OIL PUMP INSTALLATION • Lubricate the O-ring with grease or engine oil before installation. • Make sure that the oil pump is inserted into the crankcase. • Apply molybdenum disulfide or grease to the pump pinion. Bolts Grease or Engine Oil Install the oil pump onto the crankcase.

  • Page 85: Oil Pump Bleeding

    . LUBRICATION SYSTEM ATV 50 Oil Outlet Line OIL PUMP BLEEDING • Air in the oil lines will block oil flow and result in severe engine damage. • Bleed air from the oil lines and oil pump whenever the oil lines or pump have been removed or there is air in the oil lines.

  • Page 86: Oil Tank

    . LUBRICATION SYSTEM ATV 50 Wire Connector OIL TANK OIL TANK REMOVAL Remove the seat. ( 2-3 or 2-8) Remove the oil meter connector. Remove the one bolt and one nut from the oil tank. (see page 2-14) Disconnect the oil inlet line. Drain the oil inside the oil tank into a clean container.
  • Page 87 . FUEL SYSTEM ATV 50 __________________________________________________________________________________ FUEL SYSTEM SERVICE INFORMATION------------------------------------------------ 5- 2 TROUBLESHOOTING----------------------------------------------------- 5- 2 THROTTLE VALVE DISASSEMBLY/CARBURETOR REMOVAL-- 5- 3 AUTO BYSTARTER ------------------------------------------------------- 5- 6 FLOAT/FLOAT VALVE/JETS/FLOAT CHAMBER------------------ 5- 8 CARURETOR INSTALLATION ----------------------------------------- 5-11 AIR SCREW ADJUSTMENT --------------------------------------------- 5-12 REED VALVE --------------------------------------------------------------- 5-13 FUEL TANK ----------------------------------------------------------------- 5-14 FUEL VALVE REMOVAL ------------------------------------------------ 5-15...
  • Page 88 . FUEL SYSTEM ATV 50...

  • Page 89: Fuel System

    . FUEL SYSTEM ATV 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • When working with gasoline, keep away from sparks and flames.. • Note the locations of O-rings when disassembling and replace them with new ones during assembly. • All cables, fuel lines and wires must be routed and secured at correct locations. •...

  • Page 90: Throttle Valve Disassembly/Carburetor Removal

    . FUEL SYSTEM ATV 50 Carburetor Cap THROTTLE VALVE DIS- ASSEMBLY/CARBURETOR REMOVAL Loosen the carburetor cap and remove the throttle valve. Disconnect the throttle cable from the throttle valve. Throttle Valve Carburetor Cap Rubber Seal Remove the throttle valve spring, carburetor cap and rubber seal.
  • Page 91 . FUEL SYSTEM ATV 50 Remove the jet needle by removing the needle clip. Needle Clip Check the jet needle and throttle valve for wear or damage. Needle Retainer 2nd Notch (STD) Jet Needle Throttle Valve Carburetor Cap Rubber Seal THROTTLE VALVE INSTALLA-TION Install the jet needle on the throttle valve and secure with the needle clip.
  • Page 92 . FUEL SYSTEM ATV 50 Groove Install the throttle valve by aligning the groove in the throttle valve with the throttle stop screw. Carburetor Cap Tighten the carburetor cap. After installation, perform the following adjustments and inspections. • Throttle cable free play ( 3-3) •...

  • Page 93: Auto Bystarter

    . FUEL SYSTEM ATV 50 Remove the two carburetor lock nuts. Remove the carburetor. Nuts AUTO BYSTARTER AUTO BYSTARTER INSPECTION Measure the resistance between the auto bystarter wire terminals. Resistance: 5Ω (10 minutes minimum after stopping the engine) If the resistance exceeds 5Ω, replace the auto bystarter with a new one.
  • Page 94 . FUEL SYSTEM ATV 50 Connect the auto bystarter yellow wire to the battery positive (+) terminal and green/ black wire to the battery negative (-) terminal and wait 5 minutes. Connect a hose to the fuel enriching circuit and blow the hose with mouth. If air can be blown into the hose, the auto bystarter is faulty and replace it with a new one.

  • Page 95: Float/Float Valve/Jets/Float Chamber

    . FUEL SYSTEM ATV 50 Screws Auto Bystarter AUTO BYSTARTER INSTALLATION Install the auto bystarter into the carburetor body until it bottoms.. Install the set plate and then tighten the two screws. Set Plate FLOAT/FLOAT VALVE/JETS FLOAT CHAMBER Remove the two float chamber screws and the float chamber.
  • Page 96 . FUEL SYSTEM ATV 50 Float Valve FLOAT/FLOAT VALVE INSPECTION Inspect the float for damage or fuel inside the float. Check the float valve seat for wear or damage. Float Seat Main Jet JETS/SCREWS REMOVAL Before removing the throttle stop screw or air screw, record the number of rotations until it seats lightly.
  • Page 97 . FUEL SYSTEM ATV 50 Needle Jet holder Main Jet FLOAT CHAMBER ASSEMBLY Install the main jet and needle jet holder. Install the air screw and throttle stop screw according to the rotations recorded. If the air screw must be replaced, be sure to perform the air screw adjustment again.

  • Page 98: Caruretor Installation

    . FUEL SYSTEM ATV 50 O-rings CARBURETOR INSTALLATION When installation, do not allow foreign particles to enter the carburetor. Check the carburetor insulator and O-ring for wear or damage. Insulator Install the carburetor and insulator onto the intake manifold and tighten the two lock nuts.

  • Page 99: Air Screw Adjustment

    . FUEL SYSTEM ATV 50 AIR SCREW ADJUSTMENT Air Screw Turn the air screw clockwise until it seats lightly and back it to the specification given. Do not force the air screw against its seat to prevent damage. Start the engine and turn the air screw in or out slowly to obtain the highest engine speed.

  • Page 100: Reed Valve

    . FUEL SYSTEM ATV 50 Bolts REED VALVE REMOVAL Remove the four intake manifold bolts and gasket. Remove the reed valve and gasket. Intake Manifold Reeds Reed Stopper INSPECTION Check the reed valve for damaged or weak reeds. Check the reed valve seat for cracks, damage or clearance between the seat and reed.

  • Page 101: Fuel Tank

    . FUEL SYSTEM ATV 50 Lever Seat FUEL TANK FUEL TANK REMOVAL Warning • Keep sparks and flames away from the work area. • Wipe off any spilled gasoline. Remove the seat. Remove the center cover. Remove the right and left front fender. Screws Bolts Remove two bolts and two nuts on the end of...

  • Page 102: Fuel Valve Removal

    . FUEL SYSTEM ATV 50 Fuel Tubes FUEL VALVE REMOVAL Disconnect the fuel tubes and remove the bolts. Fuel Valve Fuel Valve Remove the fuel valve and fuel cup. Fuel Valve Body Control Switch Washer Remove the screw on the fuel valve control switch.
  • Page 103 . ENGINE REMOVAL/INSTALLATION ATV 50 __________________________________________________________________________________ ENGINE REMOVAL/INSTALLATION SERVICE INFORMATION------------------------------------------------ 6- 1 ENGINE REMOVAL ------------------------------------------------------- 6- 2 ENGINE INSTALLATION ------------------------------------------------ 6- 5...
  • Page 104 6. ENGINE REMOVAL/INSTALLATION ATV 50 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 motorcycle body during engine removal. •...

  • Page 105: Engine Removal

    Remove the carburetor cap. Carburetor Cap Bolts A.C.Generator/Pulser Wire Connector MX’ER 50 Disconnect the auto bystarter, A.C. generator/pulser and starter motor wire connectors. Auto Bystarter Starter Motor Wire Connector Wire Connector A.C.Generator Wire Connectors MXU 50 REVERSE MXU 50 Pulser Wire Connectors...
  • Page 106 6. ENGINE REMOVAL/INSTALLATION ATV 50 Starter Motor Wire Connector MXU 50 REVERSE MXU 50 Auto Bystarter Wire Connector Spark Plug Cap Remove the spark plug cap. Carburetor Lock Nuts Oil Outlet Line Disconnect the oil pump control cable from the pump body.
  • Page 107 . ENGINE REMOVAL/INSTALLATION ATV 50 Drive Select Rod Neutral Switch Connectors MXU 50 REVERSE: Disconnect the neutral switch connectors. Remove the bolt/nut at drive select rod, then remove the drive select rod from drive select arm. Bolt/Nut Drive Select Arm...

  • Page 108: Engine Installation

    6. ENGINE REMOVAL/INSTALLATION ATV 50 Bolt/Nut Remove the engine any connector thing. Remove the rear right engine bracket bolt/nut (MXU 50/MX’ER 50). Remove the front right engine bracket bolt/nut. Bolt/NUT Remove the front left engine bracket bolt/nut. Remove the rear left engine bracket bolt/nut.

  • Page 109: Cylinder Head/Cylinder/Piston

    CYLINDER HEAD/CYLINDER/PISTON ATV 50 __________________________________________________________________________________ CYLINDER HEAD/CYLINDER/PISTON SERVICE INFORMATION------------------------------------------------ 7-2 TROUBLESHOOTING----------------------------------------------------- 7-2 CYLINDER HEAD---------------------------------------------------------- 7-3 CYLINDER/PISTON ------------------------------------------------------- 7-6...
  • Page 110 CYLINDER HEAD/CYLINDER/PISTON ATV 50...

  • Page 111: Service Information

    CYLINDER HEAD/CYLINDER/PISTON ATV 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • The cylinder head, cylinder and piston can be serviced with the engine installed in the frame. • Before disassembly, clean the engine to prevent dust from entering the engine. • Remove all gasket material from the mating surfaces. •...

  • Page 112: Cylinder Head

    CYLINDER HEAD/CYLINDER/PISTON ATV 50 Spark Plug Cap CYLINDER HEAD REMOVAL Remove the spark plug cap. Remove the exhaust muffler. ( 2-15 or 2- Bolts Remove the three bolts attaching the fan cover to remove the fan cover. Remove the bolt attaching the engine hood to remove the engine hood.
  • Page 113 CYLINDER HEAD/CYLINDER/PISTON ATV 50 Combustion Chamber COMBUSTION CHAMBER DECABONIZING Remove the carbon deposits from the combustion chamber Avoid damaging the combustion cham- ber wall and cylinder mating surface. Mating Surface CYLINDER HEAD INSPECTION Check the cylinder head for warpage with a straight edge and feeler gauge.
  • Page 114 CYLINDER HEAD/CYLINDER/PISTON ATV 50 Cylinder head Bolts Cylinder Head Bolts Installation Install and tighten the cylinder head bolts diagonally in 2 or 3 times. Torque: 1.6 kgf-m (16 N-m, 11.5 lbf-ft) Install the spark plug. Torque: 1.4 kgf-m (14 N-m, 10.1 lbf-ft) Spark Plug Cylinder Head Engine Hood...

  • Page 115: Cylinder/Piston

    CYLINDER HEAD/CYLINDER/PISTON ATV 50 Cylinder CYLINDER/PISTON CYLINDER REMOVAL Remove the reed valve (seep page 5-13). Remove the cylinder head. Remove the cylinder. Remove the cylinder gasket. Do not pry between the cylinder and crankcase or strike the fins. Piston Piston Pin PISTON REMOVAL Remove the piston pin clip to remove the piston pin and piston.
  • Page 116 CYLINDER HEAD/CYLINDER/PISTON ATV 50 CYLINDER/PISTON INSPECTION Check the cylinder and piston for wear or damage. Clean carbon deposits from the exhaust port area. Be careful not to damage the cylinder inside wall. Measure the cylinder bore at three levels of A, B and C in both X and Y directions.
  • Page 117 CYLINDER HEAD/CYLINDER/PISTON ATV 50 A Mark The cylinder has an “A” mark or no mark on it. When replacing the cylinder with a new one, use a cylinder having the same mark as the old one. Measure the piston O.D. at a point 5 mm (0.2 in) from the bottom of the piston skirt.
  • Page 118 CYLINDER HEAD/CYLINDER/PISTON ATV 50 PISTON RING INSPECTION Measure each piston ring end gap. Service Limits: Top/Second: 0.4 mm (0.016 in) replace if over Set each piston ring squarely into the cylinder using the piston and measure the end gap. Piston Pin CONNECTING ROD SMALL END INSPECTION Install the piston pin and bearing in the...
  • Page 119 CYLINDER HEAD/CYLINDER/PISTON ATV 50 “IN” Mark Install a new cylinder gasket on the mating Cylinder Gasket surface between the cylinder and crankcase. Position the piston “IN” mark on the intake valve side. Ring Pins Make sure that the ring end gaps are aligned with the piston ring pins in the ring grooves.
  • Page 120 . A.C. GENERATOR ATV 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ A.C. GENERATOR __________________________________________________________________________________ SERVICE INFORMATION ..............8-2 A.C. GENERATOR REMOVAL............8-3 A.C. GENERATOR INSTALLATION ..........8-4...
  • Page 121 . A.C. GENERATOR ATV 50...

  • Page 122: . A.c. Generator

    . A.C. GENERATOR ATV 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • All A.C. generator maintenance and inspection can be made with the engine installed. • Refer to Section 15, 16 for A.C. generator inspection. TORQUE VALUE Flywheel nut : 3.8 kgf-m (38 N-m, 27.4 lbf-ft) SPECIAL TOOLS Flywheel puller A120E00001...

This manual is also suitable for:

Mx'er 50

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