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KYMCO NEXXON 50 Service Manual

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PREFACE
This Service Manual describes the
technical features and servicing
procedures for the KYMCO NEXXON
50.
Section 1 contains the precautions for all
operations stated in this manual. Read
them carefully before starting any
operation.
Section 2 is the inspection/ adjustment
procedures, safety rules and service
information for each part, starting from
periodic maintenance.
Sections 3 and 4 state the servicing
procedures and cautions for the removal
and installation of lubrication and fuel
systems.
Sections 5 through 18 give instructions
for disassembly, assembly and inspection
of engine, chassis frame and electrical
equipment.
Most sections start with an assembly or
system illustration and troubleshooting
for the section. The subsequent pages
give detailed procedures for the section.
Our company reserves right to make
any alteration in the design
information and contents included in
this manual may be different from the
motorcycle in case specifications are
changed.
KWANG YANG MOTOR CO., LTD.
OVERSEAS SALES DEPARTMENT
OVERSEAS SERVICE SECTION
The
.
NEXXON

TABLE OF CONTENTS

EXHAUST EMISSION CONTROL
SYSTEM
50
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6
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12
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Summary of Contents for KYMCO NEXXON 50

  • Page 1: Table Of Contents

    TABLE OF CONTENTS This Service Manual describes the GENERAL INFORMATION technical features and servicing INSPECTION/ADJUSTMENT procedures for the KYMCO NEXXON LUBRICATION SYSTEM Section 1 contains the precautions for all FUEL SYSTEM operations stated in this manual. Read them carefully before starting any ENGINE REMOVAL/INSTALLATION operation.

  • Page 2: General Information

    . GENERAL INFORMATION NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ GENERAL INFORMATION __________________________________________________________________________________ ENGINE SERIAL NUMBER ---------------------------------------------- 1- 1 SPECIFICATIONS ---------------------------------------------------------- 1- 2 SERVICE PRECAUTIONS ------------------------------------------------ 1- 3 TORQUE VALUES --------------------------------------------------------- 1-11 SPECIAL TOOLS ----------------------------------------------------------- 1-12 LUBRICATION POINTS -------------------------------------------------- 1-13 CABLE &...

  • Page 3: Engine Serial Number

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

  • Page 4: Specifications

    . GENERAL INFORMATION NEXXON 50 SPECIFICATIONS Motorcycle name & Model No. LFA3 Air cleaner type Wet, single Motorcycle name NEXXON 50 Fuel capacity 4liter Overall length (mm) 1975 Type Overall width (mm) Piston dia. (mm) φ11equivalent Overall height (mm) 1125 Venturi dia.(mm)

  • Page 5: Service Precautions

    . GENERAL INFORMATION NEXXON 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 6 . GENERAL INFORMATION NEXXON 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 7 . GENERAL INFORMATION NEXXON 50 If the fuse is burned out, find the cause and repair it. Replace it with a new one Confirm according to the specified capacity. 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 8 . GENERAL INFORMATION NEXXON 50 The connector shall be inserted completely. If the double connector has a lock, Snapping! 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 9 . GENERAL INFORMATION NEXXON 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 10 . GENERAL INFORMATION NEXXON 50 Route harnesses so they are neither Do not pull pulled tight nor have excessive slack. 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 11 . GENERAL INFORMATION NEXXON 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 12 . GENERAL INFORMATION NEXXON 50 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 Engine Oil lubrication.) : Apply grease for lubrication.

  • Page 13: Torque Values

    . GENERAL INFORMATION NEXXON 50 TORQUE VALUES STANDARD TORQUE VALUES Item Torque (kg-m) Item Torque (kg-m) 5mm bolt, nut 0.45～0.6 5mm screw 0.35～0.5 6mm bolt, nut 0.8～1.2 6mm nut, SH bolt 0.7～1.1 8mm bolt, nut 1.8～2.0 6mm flange bolt, nut 1.0～1.4...

  • Page 14: Special Tools

    . GENERAL INFORMATION NEXXON 50 FRAME Item Quantity Thread Torque (kg-m) Remarks Steering stem lock nut 25.4 6.0～9.0 Steering top cone race 25.4 0.5～1.3 Front axle nut 5.5～7.0 Rear axle nut 6.0～8.0 3.0～4.0 Rear shock absorber upper mount bolt 3.0～4.0...

  • Page 15: Lubrication Points

    . GENERAL INFORMATION NEXXON 50 LUBRICATION POINTS or CABLE LUBRICANT SPEEDOMETER, THROTTLE, BRAKE CABLE THROTTLE GRIP CHAIN LUBRICANT DRIVE CHAIN STEERING HEAD BEARINGS WHEEL BEARINGS SWING ARM PIVOT VUSHINGS BRAKE PEDAL PIVOT SPEEDOMETER CENTER & SIDE GEAR STAND PIVOTS BRAKE CAM...

  • Page 16: Cable & Harness Routing

    . GENERAL INFORMATION NEXXON 50 CABLE & HARNESS ROUTING Throttle Cable Front brake hose Ignition Switch Horn Winker Relay 1-14...
  • Page 17 . GENERAL INFORMATION NEXXON 50 Regulator/ Front Brake Rectifier Hose Wire Harness Start Mac Starter Ignition Coil Ignition Motor Fusc Coil Wire 1-15...

  • Page 18: Wiring Diagram

    . GENERAL INFORMATION NEXXON 50 WIRING DIAGRAM 1-16...

  • Page 19: Inspection/Adjustment

    . GENERAL INFORMATION NEXXON 50 TROUBLESHOOTING ENGINE WILL NOT START OR IS HARD TO START Symptom Inspection/Adjustment Probable Cause Check if fuel reaches carburetor by loosening drain screw Empty fuel tank Clogged carburetor fuel inlet tube, vacuum tube or fuel tube...
  • Page 20 . GENERAL INFORMATION NEXXON 50 POOR PERFORMANCE (ESPECIALLY AT IDLE AND LOW SPEEDS) Probable Cause Inspection/Adjustment Symptom Check ignition timing Faulty CDI unit Incorrect Correct Faulty pulser coil Check carburetor air screw adjustment Mixture too lean (turn screw in) Correctly adjusted...
  • Page 21 . GENERAL INFORMATION NEXXON 50 POOR PERFORMANCE (ENGINE LACKS POWER) Inspection/Adjustment Probable Cause Symptom Start engine and accelerate lightly for observation Clogged air cleaner Poor fuel flow (Restricted) Clogged fuel tank cap breather hole Engine speed Engine speed does not...
  • Page 22 . GENERAL INFORMATION NEXXON 50 POOR PERFORMANCE (AT HIGH SPEED) Inspection/Adjustment Symptom Probable Cause Check ignition timing Faulty CDI unit Correct Incorrect Faulty pulser coil Check valve clearance Improperly adjusted valve clearance Correct Incorrec Worn valve seat filter Check fuel...
  • Page 23 . GENERAL INFORMATION NEXXON 50 POOR CHARGING (BATTERY OVER DISCHARGING OR OVERCHARGING) Undercharging Inspection/Adjustment Symptom Probable Cause Start engine and test limit voltage between battery terminals Dead battery Voltage does not Normal voltage increase Faulty battery Measure resistance between AC generator...
  • Page 24 . GENERAL INFORMATION NEXXON 50 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 old spark plug Check spark plug cap and ignition coil wire for...
  • Page 25 . INSPECTION/ADJUSTMENT NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ INSPECTION/ADJUSTMENT __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 2- 1 MAINTENANCE SCHEDULE-------------------------------------------- 2- 2 FUEL LINE/FILTER-------------------------------------------------------- 2- 3 THROTTLE OPERATION/CHOKE-------------------------------------- 2- 3 AIR CLEANER -------------------------------------------------------------- 2- 4 SPARK PLUG---------------------------------------------------------------- 2- 4 VALVE CLEARANCE ----------------------------------------------------- 2- 5...

  • Page 26: Service Information

    . INSPECTION/ADJUSTMENT NEXXON 50 SERVICE INFORMATION GENERAL ！ WARNING •Before running the engine, make sure that the working area is well-ventilated. Never run the engine in a closed area. The exhaust contains poisonous carbon monoxide gas which may cause death to people.

  • Page 27: Maintenance Schedule

    . INSPECTION/ADJUSTMENT NEXXON 50 MAINTENANCE SCHEDULE Perform the periodic maintenance at each scheduled maintenance period. I: Inspect, and Clean, Adjust, Lubricate, Refill, Repair or Replace if necessary. A: Adjust C: Clean R: Replace T : Tighten Regular Service Mileage (km)

  • Page 28: Fuel Line/Filter

    . INSPECTION/ADJUSTMENT NEXXON 50 FUEL LINE/FILTER Fuel Filter Check the fuel lines and replace any parts which show signs of deterioration, damage or leakage. ＊ Do not smoke or allow flames or sparks in your working area. THROTTLE OPERATION Check for smooth throttle grip movement in all steering positions.

  • Page 29: Air Cleaner

    . INSPECTION/ADJUSTMENT NEXXON 50 AIR CLEANER Air Cleaner Case Cover Air Cleaner Case AIR CLEANER REPLACEMENT Remove the right center cover. (page 14-3) Remove the air cleaner case. (page 4-5) Remove the air cleaner case cover screws and the cover. (page 4-5) Remove the air cleaner screen and element.

  • Page 30: Valve Clearance

    . INSPECTION/ADJUSTMENT NEXXON 50 Cylinder Head Cover VALVE CLEARANCE ＊ Inspect and adjust valve clearance while the engine is cold (below 35℃). Remove the cylinder head cover. Bolts “T” Mark Rotate the generator flywheel to locate the camshaft on the top dead center (TDC) and align the “T”...

  • Page 31: Ignition Timing

    . INSPECTION/ADJUSTMENT NEXXON 50 IGNITION TIMING ＊ • The CDI unit is not adjustable. • If the ignition timing is incorrect, check the ignition system. Remove the ignition timing eye hole cap on the left crankcase cover. Eye Hole Check the ignition timing with a timing light.

  • Page 32: Engine Oil

    . INSPECTION/ADJUSTMENT NEXXON 50 Lower Limit Upper Limit ENGINE OIL ＊ When checking the oil level, place the motorcycle on its main stand on level ground for oil level check. After the engine is stopped for 10 minutes, check if the oil level is between the upper and lower limits.

  • Page 33: Clutch

    . INSPECTION/ADJUSTMENT NEXXON 50 BRAKE SHOE Inspect the front brake linings for wear. BRAKE LEVER/PEDAL Measure the rear brake pedal free play. Free Play: 20～30mm Adjusting Bolt Lock Nut CLUTCH Stop the engine. Loosen the lock nut. Slowly turn the adjusting bolt...

  • Page 34: Suspension

    . INSPECTION/ADJUSTMENT NEXXON 50 SUSPENSION FRONT Fully apply the front brake lever and check the action of the front shock absorbers by compressing them several times. Check the entire shock absorber assembly for oil leaks, looseness or damage. REAR Check the action of the rear shock absorber by compressing it several times.

  • Page 35: Steering Handlebar

    . INSPECTION/ADJUSTMENT NEXXON 50 Check the front and rear axle nuts for looseness. If the axle nuts are loose, tighten them to the specified torques. Torques: Front : 5.5～7.0kg-m Rear : 6.0～8.0kg-m Front Axle Nut STEERING HANDLEBAR Check that the control cables do not interfere with handlebar rotation.

  • Page 36: Lubrication System

    . LUBRICATION SYSTEM NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ LUBRICATION SYSTEM __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 3- 2 TROUBLESHOOTING----------------------------------------------------- 3- 2 ENGINE OIL/OIL FILTER ------------------------------------------------ 3- 3 OIL PUMP/OIL FILTER ROTOR ---------------------------------------- 3- 4...
  • Page 37 . LUBRICATION SYSTEM NEXXON 50...

  • Page 38: Lubrication System

    . LUBRICATION SYSTEM NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • The service and maintenance of this section 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 39: Engine Oil/Oil Filter

    . LUBRICATION SYSTEM NEXXON 50 Upper Limit ENGINE OIL/OIL FILTER OIL LEVEL ＊ • Place the motorcycle upright on level ground for engine oil level check. • Run the engine for 2～3 minutes and check the oil level after the engine is stopped for 2～3 minutes.

  • Page 40: Oil Pump/Oil Filter Rotor

    . LUBRICATION SYSTEM NEXXON 50 OIL PUMP/OIL FILTER ROTOR REMOVAL Remove the right crankcase cover (page 9-3) ＊ When installing, make sure to use a new right crankcase cover gasket. Right Crankcase Cover Gasget Oil Filter Rotor Cover OIL FILTER ROTOR Remove the filter rotor cover and gasket (pqge 9-3).
  • Page 41 . LUBRICATION SYSTEM NEXXON 50 INSPECTION Install the drive shaft and rotors. Measure the rotor tip clearance. Service limit: 0.2mm Measure the pump body clearance. Service limit: 0.2mm Install the gasket and measure the rotor end clearance. Service limit: 0.15mm...
  • Page 42 . LUBRICATION SYSTEM NEXXON 50 Pump Cover Install a new pump body cover gasket and the cover. ＊ Make sure that the pump rotates freely without binding. Gasket Gasket INSTALLATION Install the oil pump with a new gasket under it by aligning the slot if the drive shaft with the cam chain guide spindle.

  • Page 43: Fuel System

    . FUEL SYSTEM NEXXON 50 _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ FUEL SYSTEM _____________________________________________________________________________________________ SERVICE INFORMATION ------------------------------------------------ 4- 2 TROUBLESHOOTING----------------------------------------------------- 4- 3 AIR CLEANER REMOVAL ----------------------------------------------- 4-4 THROTTLE VALVE DISASSEMBLY ----------------------------------- 4- 5 THROTTLE VALVE INSTALLATION ---------------------------------- 4- 6 CARBURETOR REMOVAL----------------------------------------------- 4- 7...
  • Page 44 . FUEL SYSTEM NEXXON 50...

  • Page 45: Fuel System

    . FUEL SYSTEM NEXXON 50 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 46: Troubleshooting

    . FUEL SYSTEM NEXXON 50 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 47: Air Cleaner Removal

    . FUEL SYSTEM NEXXON 50 Bolt AIR CLEANER REMOVAL Remove the front cover (page 14-3). Remove the screw attaching the carburetor. Remove the air cleaner case by removing the attaching bolts. Screw Screw Element Remove the four screws with the air cleaner case cover.

  • Page 48: Throttle Valve Disassembly

    . FUEL SYSTEM NEXXON 50 THROTTLE VALVE DIS- ASSEMBLY Remove the front cover (page 14-3). Loosen the carburetor cap and remove the throttle valve. Carburetor Cap Throttle Valve Disconnect the throttle cable from the throttle valve. Throttle Valve Throttle Cable Remove the throttle valve, spring and carburetor top.

  • Page 49: Throttle Valve Installation

    . FUEL SYSTEM NEXXON 50 Throttle Valve Throttle Cable THROTTLE VALVE INSTALLA- TION Set the needle clip on the jet needle clip. Standard podition: 3rd groove from the top Install the jet needle on the throttle valve. Install the retainer on the throttle valve and secure the jet needle.

  • Page 50: Carburetor Removal

    . FUEL SYSTEM NEXXON 50 CARBURETOR REMOVAL Remove the front cover (page 14-3). Loosen the air cleaner connecting tube band. Carburetor top Remove the carburetor top (page 4-6). Choke Cable Remove the fuel tube from the carburetor. Remove the choke cable.
  • Page 51 . FUEL SYSTEM NEXXON 50 Float/Float Valve Disassembly Remove the four float chamber attaching screws and remove the float chamber. Screws Remove the float pin, float and float valve. Float FLOAT/FLOAT VALVE INSPECTION Inspect the float valve seat for wear or damage.
  • Page 52 . FUEL SYSTEM NEXXON 50 Remove the air screw and throttle stop screw. Throttle Stop Screw CAUTIONS ! ＊ • Be careful not to damage the jets and jet holder when removing them. • Before removing, turn the throttle stop screw...
  • Page 53 . FUEL SYSTEM NEXXON 50 FLOAT LEVEL INSPECTION Turn the carburetor upside down so that the float will go down to make the float valve contact the float valve seat. Then slowly tilt the carburetor and measure the float level with the float level gauge while the float pin just contacts with float valve.
  • Page 54 . FUEL SYSTEM NEXXON 50 FUEL TANK Fuel Unit Wire FUEL TANK REMOVAL Warning • Keep sparks and flames away from the work area. • Wipe off any spilled gasoline. Turn the fuel valve to “OFF”. Remove the three bolts attaching the rear carrier.

  • Page 55: Engine Removal/Installation

    . ENGINE REMOVAL/INSTALLATION NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ ENGINE REMOVAL/INSTALLATION __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 5- 1 ENGINE REMOVAL ------------------------------------------------------- 5- 2 ENGINE INSTALLATION ------------------------------------------------ 5- 3...

  • Page 56: Cylinder Head/Valves

    5. ENGINE REMOVAL/INSTALLATION NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • A engine stand or floor jack is required to support and maneuver the engine. • The following parts can be serviced with the engine installed in the frame: ⎯ Cylinder head/valves (Section 6) ⎯...
  • Page 57 . ENGINE REMOVAL/INSTALLATION NEXXON 50 Carburetor Bolt ENGINE REMOVAL Remove the right and left decorative covers under the seat. Remove the carburetor (page 4-5). Screw Exhaust Muffler Remove the two exhaust muffler joint lock nuts. Remove the exhaust muffler hanger lock bolt and exhaust muffler.
  • Page 58 5. ENGINE REMOVAL/INSTALLATION NEXXON 50 Bolts Gearshift Pedal Remove the gear shift lever bolt and gear shift lever. Remove the two bolts attaching the left rear crankcase cover and remove the rear crankcase cover. Rear Crankcase Cover Drive Chain Bolts...
  • Page 59 . CYLINDER HEAD/VALVES NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ CYLINDER HEAD/VALVES __________________________________________________________________________________ SCHEMATIC DRAWING ------------------------------------------------- 6- 1 SERVICE INFORMATION------------------------------------------------ 6- 2 TROUBLESHOOTING----------------------------------------------------- 6- 3 CYLINDER HEAD REMOVAL ------------------------------------------ 6- 4 CYLINDER HEAD DISASSEMBLY ------------------------------------ 6- 5 CYLINDER HEAD ASSEMBLY ----------------------------------------- 6- 8...

  • Page 60: Schematic Drawing

    . CYLINDER HEAD/VALVES NEXXON 50 SCHEMATIC DRAWING...

  • Page 61: Service Information

    . CYLINDER HEAD/VALVES NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • The cylinder head can be serviced with the engine installed in the frame. Coolant in the radiator and water jacket must be drained first. • When assembling, apply molybdenum disulfide grease or engine oil to the valve guide movable parts and valve arm sliding surfaces for initial lubrication.

  • Page 62: Troubleshooting

    . CYLINDER HEAD/VALVES NEXXON 50 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 63: Cylinder Head Removal

    . CYLINDER HEAD/VALVES NEXXON 50 Bolt Left Side Cover CYLINDER HEAD REMOVAL Remove the left crankcase cover bolt. Remove the left crankcase cover. Remove the crankshaft hole cap and timing hole cap. Remove the left side cover and gasket. Remove the cam chain tensioner sealing bolt, washer, spring and tensioner shaft.(See the...

  • Page 64: Cylinder Head Disassembly

    . CYLINDER HEAD/VALVES NEXXON 50 Right Side Cover CYLINDER HEAD DISASSEMBLY Remove the two bolts and the right side cover. Bolts Screw a 8mm bolt into the rocker arm shaft, and pull it out of the cylinder head. Rocker Arm Shaft...
  • Page 65 . CYLINDER HEAD/VALVES NEXXON 50 Remove carbon deposits from the combustion chamber. Clean any gasket material from the cylinder head mating surface. ＊ Be careful not to damage the cylinder head mating surface and valve seat. CYLINDER HEAD INSPECTION Check the spark plug hole and valve areas for cracks.
  • Page 66 . CYLINDER HEAD/VALVES NEXXON 50 ROCKER ARM INSPECTION Measure the I.D. of each valve rocker arm. Service Limits: IN: 10. mm replace if over EX: 10. mm replace if over ROCKER ARM SHAFT INSPECTION Measure each rocker arm shaft O.D.

  • Page 67: Cylinder Head Assembly

    . CYLINDER HEAD/VALVES NEXXON 50 Measure each valve guide I.D. Service Limits: IN: 5.00mm replace if over EX: 5.00mm replace if over Subtract each valve stem O.D. from the corresponding guide I.D. to obtain the stem- to-guide clearance. Service Limits: IN: 0.10mm replace if over EX: 0.10mm replace if over...
  • Page 68 . CYLINDER HEAD/VALVES NEXXON 50 Tap the valve stems gently with a plastic hammer to firmly seat the cotters. ＊ Be careful not to damage the valves. Camshaft Rocker Arms Coat the camshaft, camshaft bearings and automatic decompressor cam with clean engine oil.

  • Page 69: Cylinder Head Installation

    . CYLINDER HEAD/VALVES NEXXON 50 Dowel Pins CYLINDER HEAD INSTALLATION Clean the cylinder head gasket surface of any gasket material. ＊ Be careful not to enter dust and dirt into the cylinder. Install the dowel pins and a new cylinder head gasket.
  • Page 70 . CYLINDER HEAD/VALVES NEXXON 50 Left Side Install the left side cover on the left Gasket side cover. Install the left side cover. Adjust the valve clearance. Gasket 6-11...
  • Page 71 . CYLINDER/PISTON NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ CYLINDER/PISTON __________________________________________________________________________________ SCHEMATIC DRAWING -------------------------------------------------- 7- 1 SERVICE INFORMATION ------------------------------------------------ 7- 2 TROUBLESHOOTING----------------------------------------------------- 7- 2 CYLINDER REMOVAL --------------------------------------------------- 7- 3 PISTON REMOVAL -------------------------------------------------------- 7- 4 PISTON INSTALLATION ------------------------------------------------- 7- 6 CYLINDER INSTALLATION--------------------------------------------- 7- 6...

  • Page 72: Schematic Drawing

    . CYLINDER/PISTON NEXXON 50 SCHEMATIC DRAWING...

  • Page 73: Service Information

    . CYLINDER/PISTON NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • The cylinder and piston can be serviced with the engine installed in the frame. • When installing the cylinder, use a new cylinder gasket and make sure that the dowel pins are correctly installed.

  • Page 74: Cylinder Removal

    . CYLINDER/PISTON NEXXON 50 Guide Roller Bolt CYLINDER REMOVAL Remove the cylinder head. Remove the cam chain guide roller. Remove the cylinder by removing the cylinder bolt. Remove all gasket material from the cylinder surface. Cylinder Bolt Guide Roller Dowel Pins Gasket Remove the gasket and dowel pins.

  • Page 75: Piston Removal

    . CYLINDER/PISTON NEXXON 50 Inspect the top of the cylinder for warpage. Service Limit: 0.05mm repair or replace if over Piston Clip PISTON REMOVAL Remove the piston pin clip. Press the piston pin out of the piston. ＊ Place a clean shop towel in the crankcase to keep the piston pin clip from falling into the crankcase.
  • Page 76 . CYLINDER/PISTON NEXXON 50 Measure the piston O.D. ＊ • Take measurement at 5mm from the bottom and 90° to the piston pin hole. Service Limit: 51.6mm replace if below Measure the piston-to-piston pin clearance. Service Limit: 0.10mm replace if over Measure the piston pin hole I.D.

  • Page 77: Piston Installation

    . CYLINDER/PISTON NEXXON 50 PISTON RING INSTALLATION Install the piston rings onto the piston. Second Apply engine oil to each piston ring. ＊ • Be careful not to damage the piston and piston rings during assembly. • All rings should be installed with the markings facing up.
  • Page 78 . CYLINDER/PISTON NEXXON 50 Coat the cylinder bore, piston and piston rings with clean engine oil. Carefully lower the cylinder over the piston by compressing the piston rings. ＊ • Be careful not to damage or break the piston rings.
  • Page 79 8. ALTERNATOR/STARTER CLUTCH/ CAM CHAIN TENSIONER NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ ALTERNATOR/STARTER CLUTCH/ CAM CHAIN TENSIONER __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 8-2 TROUBLESHOOTING----------------------------------------------------- 8-2 ALTERNATOR REMOVAL ---------------------------------------------- 8-3 STARTER CLUTCH REMOVAL ---------------------------------------- 8-4 CAM CHAIN TRNSIONER ----------------------------------------------- 8-5 TENSIONER SPRING AND PUSH ROD ------------------------------- 8-5...
  • Page 80 8. ALTERNATOR/STATER CLUTCH/ CAM CHAIN TENSIONER NEXXON SCHEMATIC DRAWING...

  • Page 81: Alternator/Starter Clutch

    8. ALTERNATOR/STARTER CLUTCH/ CAM CHAIN TENSIONER NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • The starter motor, generator, left crankcase and starter clutch can be serviced in the frame. • Do not install the starter clutch forcedly. • Install the generator by aligning the groove in the flywheel with the key on the crankshaft.

  • Page 82: Alternator Removal

    8. ALTERNATOR/STATER CLUTCH/ CAM CHAIN TENSIONER NEXXON Bolts ALTERNATOR REMOVAL Remove the four bolts. Remove the left crankcase cover. Gasket Remove the gasket and dowel pins. Dowel Pins Flywheel Holder Remove the flywheel nut and washer while holding the flywheel with a flywheel holder. Special Flywheel holder Flywheel Puller...

  • Page 83: Starter Clutch Removal

    8. ALTERNATOR/STARTER CLUTCH/ CAM CHAIN TENSIONER NEXXON 50 Clamp Bolts Remove the clamp. Remove the five bolts and alternator stator base from the crankcase cover. ＊ • Do not disassemble the stator and pulse generator coils. Stator Base STARTER CLUTCH REMOVAL...

  • Page 84: Tensioner Spring And Push Rod

    8. ALTERNATOR/STATER CLUTCH/ CAM CHAIN TENSIONER NEXXON INSPECTION Measure the driven sprocket O.D. Service Limit:37.83mm replace if over Measure the driven sprocket I.D. Service Limit:19.06mm replace if over Check the one-way clutch rollers, spring caps and springs for wear or damage. Roller Spring Spring Cap...

  • Page 85: Starter Clutch Installation

    8. ALTERNATOR/STARTER CLUTCH/ CAM CHAIN TENSIONER NEXXON 50 Check the push rod valve for clogged Check the push rod for wear or scraches. Measure the push rod O.D. Service limit: 11.945 mm One Way Valve Tensioner Tensioner Rod INSTALLATION Install the cam chain tensioner and secure it with the pivot bolt.
  • Page 86 8. ALTERNATOR/STATER CLUTCH/ CAM CHAIN TENSIONER NEXXON Install the chain, drive sprocket and driven sprocket as an assembly. Chain Stopper Plate Snap Ring Install the following components: -snap ring. -stopper plate. -chain sliders. Chain Sliders Grommet Clamp Bolts Install the alternator stator base and secure it with the two bolts.
  • Page 87 8. ALTERNATOR/STARTER CLUTCH/ CAM CHAIN TENSIONER NEXXON 50 Gasket Install the dowel pins and a new gasket. Dowel Pins Bols Install the left crankcase cover and tighten the four bolts. Torque: 0.8～1.2kg-m...

  • Page 88: Clutch/Gear Shift Mechanism

    . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ CLUTCH/GEAR SHIFT MECHANISM __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 9 -2 TROUBLESHOOTING----------------------------------------------------- 9 -3 RIGHT CRANKCASE COVER REMOVAL --------------------------- 9 -4 CENTRIFUGAL CLUTCH/MANUAL CLUTCH REMOVAL ------ 9 -4 CENTRIFUGAL CLUTCH/MANUAL CLUTCH INSTALLATION 9 -8...
  • Page 89 . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50...

  • Page 90: Clutch/Gear Shift Mechanism

    . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • The clutch and gear shift mechanism can be serviced in the frame. • Install the clutch plates in the same chamfer direction. • Install the thrust washer with the chamfer facing up and the flat facing down.

  • Page 91: Troubleshooting

    . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 TROUBLESHOOTING Faulty clutch operation can usually be corrected by adjusting the clutch. Clutch slips when accelerating • Faulty clutch lifter mechanism • Discs worn • Weak spring • Incorrect clutch adjustment Clutch will not disengage •...

  • Page 92: Right Crankcase Cover Removal

    . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 Bolts RIGHT CRANKCASE COVER REMOVAL Drain the engine oil (page 3-3). Remove the kickstarter pedal. Remove the right crankcase cover attaching bolts and right crankcase cover. Remove the dowel pins and gasket. Clutch Lifter...
  • Page 93 . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 Install the clutch holder and secure it with Clutch Holder the bolts. Remove the lock nut and plane washer using a lock nut wrench. Remove the clutch. Special Clutch holder Lock nut wrench Lock Nut Wrench Remove the clutch square nut.
  • Page 94 . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 Washer Guide Clutch Center Remove the follows: - Gear primary drive. -Guide clutch center. - Washer Gear primary drive MANUAL CLUTCH DISASSEMBLY Remove the set ring(101.5mm) Set Ring(101.5mm) Remove the four bolts(5*10mm) Bolts(5*10mm) Plate Drive...
  • Page 95 . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 Measure the O.D. of the crankshaft at the crankshaft primary drive gear. SERVICE LIMIT: 17.00mm Driven Gear Gear Primary INSPECTION CLUTCH GEAR O.D/I.D Clutch Outer Outer Drive Inspect the clutch outer groove for scratches caused by the friction disks.

  • Page 96: Centrifugal Clutch/Manual Clutch Installation

    . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 CLUTCH A PLATE/ CLUTCH A PLATE Measure each clutch plate bending using a feeler gauge. Service Limit: 0.20mm Plate Drive Center Clutch Driven Gear Outer CENTRIFUGAL CLUTCH/MANUAL CLUTCH Set Ring INSTALLATION MANUAL CLUTCH ASSEMBLY Coat the clutch discs and plates with clean engine oil.
  • Page 97 . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 Washer Guide Clutch Center Install the clutch outer guide onto the main shaft. Install the washer over the crankshaft. Gear primary drive Gear Primary Driver Manual Clutch Assembly Install the clutch drum and manual clutch assembly.
  • Page 98 . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 Gasket Cover Install the oil filter rotor cover and a new gasket. Secure the oil filter rotor with the three bolts. Bearing 6000 Install the clutch Bearing. Punch Mark And Notch Mark Clutch Lifter Cam Install the clutch lifter bearing and clutch lifter Cam.(page9-10-4)

  • Page 99: Gear Shift Mechanism

    . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 warcher gear shift pedal Drum stopper GEAR SHIFT MECHANISM Remove the cenrifugal clutch and manual clutch (page 9-3) Remove the warcher. Remove the gear shift spindle and washer. Remove the gear shift pedal. Gear Shift Spindle...

  • Page 100: Right Crankcase Cover Installaion

    . CLUTCH/GEAR SHIFT MECHANISM NEXXON 50 Gear Shift Spindle Install the gear shift spindle and washer. During installation, make sure that the return spring aligns with the crankcase tab. Spring Lock Nut Adjusting Bolt RIGHT CRANKCASE COVER INSTALLATION Install the new O-ring and lock nut.
  • Page 101 . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ CRANKCASE/GRANKSHAFT/TRANS- MISSION SYSTEM/STARTER SPINDLE __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 10- 2 TROUBLESHOOTING----------------------------------------------------- 10- 3 CRANKCASE REMOVAL ------------------------------------------------ 10- 4 CRANKSHAFT/KICK STARTER---------------------------------------- 10- 5 TRANSMISSION------------------------------------------------------------ 10- 7 CRANKCASE BEARING REPLACEMENT --------------------------- 10-10 CRANKCASE INSTALLATION ----------------------------------------- 10-12...

  • Page 102: Crankcase/Crankshaft/Kick Starter/Transmission

    . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION 10-1...

  • Page 103: Service Information

    . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION SERVICE INFORMATION GENERAL INSTRUCTIONS • During crankcase separation, do not separate the crankcase halves with an iron hammer to avoid crankcase deformation or damage. • After separation, be careful not to damage the right and left crankcase mating surfaces to avoid oil leakage.

  • Page 104: Troubleshooting

    . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION SPECIAL TOOLS Bearing remover Bearing remover block Universal bearing puller Bearing driver handle Pilot, 15mm Pilot, 17mm Pilot, 20mm Pilot, 22mm Inner bearing driver handle Bearing outer driver TROUBLESHOOTING Excessive engine noise • Worn main shaft journal bearing •...

  • Page 105: Crankcase Removal

    . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION Bolts CRANKCASE REMOVAL The following parts must be removed before removing the crankcase: • Cylinder head (Refer to Section 6.) • Cylinder/piston (Refer to Section 7.) • Alterantor/cam chain tensioner (Refer to Section 8.) • Clutch/gear shift mechanism (Refer to Section 9.)

  • Page 106: Crankshaft/Kick Starter

    . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION Crankshaft Kick starter spindle CRANKSHAFT/KICK STARTER REMOVAL Remove the crankshaft. Remove the kick starter spindle. CRANKSHAFT INSPECTION Measure the connecting rod big end side clearance. Service Limit: 0.80mm replace if over Measure the connecting rod big end radial clearance at two points at right angles to the shaft.
  • Page 107 . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION Turn the outer races of the crankshaft bearings with your fingers. The bearings should turn smoothly and quietly. Also check that the inner races of the bearings fit tightly on the crankshaft. Check the timing sprocket for wear or damage.

  • Page 108: Transmission

    . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION Kick Starter Spindle TRANSMISSION DISASSEMBLY Remove the kick starter spindle from the left crankcase. Countershaft Main Shaft Remove the transmission main shaft and countershaft and transmission drum and transmission forks from the left crankcase. ＊...
  • Page 109 . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION Measure the O.D. of the mainshaft and countershaft in the locations as shown. Service limit: M2, M4: 16.926mm C3, C4: 19.919mm Measure each transmission fork shaft hole I.D. Service Limit: 34.05mm replace if over Check the transmission fork shaft for bending or damage.
  • Page 110 . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION Right Left Inspect the transmission drum for scratches or poor lubrication. Check the transmission drum grooves for damage. Check the bearing for excessive free play. Measure the transmission drum O.D. Service Limits: Left : 13.05mm replace if below Right : 16.10mm replace if below...

  • Page 111: Crankcase Bearing Replacement

    . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION CRANKCASE BEARING REPLACEMENT Remove the oil pump drive shaft and drive sprocket. LEFT CRANKCASE Remove the countershaft oil seal. Drive the countershaft bearing out of the left crankcase. Bearing Oil Seal BEARING REPLACEMENT Remove the main shaft and countershaft bearings from the left and right crankcase halves using the following tools.
  • Page 112 . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION Main shaft Bearing Counter Bearing Drive in new bearings using a bearing installer. ＊ • Apply engine oil to the bearings before installation. • Drive in bearings squarely. Special Bearing installer Countershaft Oil Seal Install a new left countershaft oil seal in the left crankcase and grease the oil seal lip.

  • Page 113: Crankcase Installation

    . CRANKCASE/CRANKSHAFT/KICK NEXXON 50 STARTER/TRANSMISSION Gasket CRANKCASE INSTALLATION Install the dowel pins and a new gasket onto the left crankcase. Dowel Pins Bolts Install the right crankcase over the left crankcase. ＊ Make sure that the gasket stays in place.
  • Page 114 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ FRONT WHEEL/SUSPENSION/STEERING __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 11- 2 TROUBLESHOOTING----------------------------------------------------- 11- 3 HANDLEBAR --------------------------------------------------------------- 11- 4 FRONT WHEEL------------------------------------------------------------- 11- 7 FRONT SHOCK ABSORBER--------------------------------------------- 11-11 STEERING STEM----------------------------------------------------------- 11-16 11-0...
  • Page 115 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 SCHEMATIC DRAWING 11-1...
  • Page 116 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS SPECIFICATIONS Item Standard (mm) Service Limit (mm) ⎯ Front axle shaft runout Axial Front wheel rim runout Radial ⎯ Front fork spring free length 328.2 ⎯ Front fork tube runout ⎯...

  • Page 117: Troubleshooting

    . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 TROUBLESHOOTING Hard steering • Insufficient tire pressure • Excessively tightened steering stem nut • Damaged steering stem bearings • Damaged steering bearing races Steers to one side or does not track straight • Uneven front shock absorbers •...

  • Page 118: Front Wheel/Suspension/ Steering

    . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 cover FR handle cover FR throttle HANDLEBAR REMOVAL Remove the cover FR handle. Remove the cover RR handle Remove the handlele R switch. Remove the cover top throttle. Remove the cover low throttle. cover RR handle...
  • Page 119 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 Bolt Remove the handlebar lock nut to remove the handlebar. Handlebar Tab/Groove INSTALLATION Install the handlebar, aligning the tabs of the handlebar with the grooves in the steering stem. Install and tighten the handlebar lock nut.
  • Page 120 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 THROTTLE PIPE INSTALLATION Clean the handlebar surface and install the throttle pipe. Check the throttle grip for proper operation. Throttle Pipe Connect the throttle cable to the throttle grip. Hole Apply grease to the throttle cable.

  • Page 121: Front Wheel

    . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 FRONT WHEEL REMOVAL Place a jack or other adjustable support under the engine to raise the front wheel off the ground. Remove the front axle nut and pull out the axle. Remove the front wheel.
  • Page 122 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 Speedometer Gearbox Tabs DISASSEMBLY Remove the speedometer gearbox and dust seal from the left side of the wheel. Dust Seal Axle Collar Remove the axle collar from the right side of the wheel. Nuts Remove the dust seal.
  • Page 123 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 Bearing Driver Handle ASSEMBLY Pack all bearing cavities with grease. First drive in the right bearing and then install the distance collar. Finally, drive in the left bearing. Special Bearing driver handle Bearing installer...
  • Page 124 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 Axle Collar Install the axle collar to the right side of the wheel. Groove INSTALLATION Install the front wheel onto the front fork, aligning the tab on the front fork with the groove in the speedometer gearbox.

  • Page 125: Front Shock Absorber

    . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 Front Shock Absorber Bolts Fender FR FRONT SHOCK ABSORBER REMOVAL Remove the front wheel. (Refer to 11-7.) Remove the fender FR (A) bolts. Remove the fender (A)FR. Remove the front shock absorber bolts. Remove the front shock absorbers.
  • Page 126 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 Use a vise to hold the front shock absorber tube and remove the damper from the shock absorber tube. ＊ When holding the shock absorber tube, place a shop towel under it and do not apply too much force.
  • Page 127 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 INSPECTION Measure the front fork spring free length. Service Limit: 328.2mm replace if below Replace the spring with a new one if it exceeds the service limit. Set the front fork tube in V blocks and measure the tube runout.
  • Page 128 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 ASSEMBLY Before assembly, clean the removed parts with high flash or non-flammable solvent. Return Spring Install the return spring and piston into the front fork tube and then install oil stopper to the piston end.
  • Page 129 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 Place shop towels under the bottom tube and set it in a vise. Apply locking agent to the 6mm Socket Spanner socket head bolt and then install it into the piston. Tighten the socket head bolt using the socket spanner.

  • Page 130: Steering Stem

    . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 Bolts INSTALLATION Install the front shock absorbers onto the steering stem. Tighten the lower mount bolts. Install the front fender. Install the front wheel. STEERING STEM REMOVAL Remove the steering handlebar. Lock Nut Socket Wrench...
  • Page 131 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 BALL RACE REPLACEMENT Remove the top and bottom ball races. Ball Race Remover Bearing Driver Handle Drive the top and bottom ball races into the steering head using a bearing driver. Special Bearing driver handle...
  • Page 132 . FRONT WHEEL/SUSPENSION/ STEERING NEXXON 50 STEERING STEM INSTALLATION Steel Balls Apply grease to the top and bottom ball races and steel balls. Install 23 steel balls each on the top and 29 steel balls on the bottom ball races. Apply grease to the ball races again and then install the steering stem.

  • Page 133: Rear Wheel/Brake/Suspension

    . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ REAR WHEEL/BRAKE/SUSPENSION __________________________________________________________________________________ SERVICE INFORMATION ..............12- 2 TROUBLESHOOTING ............... 12- 3 REAR WHEEL..................12- 4 REAR BRAKE ..................12- 7 REAR SHOCK ABSORBER............... 12-10 REAR FORK..................12-11 12-0...
  • Page 134 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 SCHEMATIC DRAWING 12-1...
  • Page 135 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • When installing the drive chain joint clip, the cutout of the clip should be opposite to the rotating direction. • After the drive chain is adjusted, make sure that the rear brake pedal free play is normal and adjust it if necessary.
  • Page 136 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 TROUBLESHOOTING Rear wheel wobbling Poor brake performance • Bent rim • Improperly adjusted brake • Worn rear wheel bearing • Worn brake linings • Loose or broken wheel spoke wires • Contaminated or damaged brake linings •...
  • Page 137 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 REAR WHEEL REMOVAL Remove the driver chain cover. Remove the exhaust muffler. Remove the rear pillion step stay. Rear Pillion Step Stay Exhaust Muffler. Rear Axle Nut Remove the rear axle nut. Remove the rear brake adjusting nut.
  • Page 138 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 Place the rear wheel in a turning stand and measure the rim runout. Service Limits: Axial: 2.0mm Radial: 2.0mm Check the wheel spoke wires for looseness. Check the wheel bearing play by placing the wheel in a turning stand and spinning the wheel by hand.
  • Page 139 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 Dust Seal DISASSEMBLY Remove the side collar and dust seal from the left side of the rear wheel. First tap the safety piece flat and then remove the four drive chain gear lock nuts. Remove the safety piece and drive chain gear.
  • Page 140 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 Side Collar Install the drive chain gear and secure it with the snap ring. Apply grease to the dust seal and install it to the bearing. Install the side collar. INSTALLATION Install the rear wheel in the reverse order of removal.
  • Page 141 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 Measure the brake drum I.D. Service Limit: 141mm replace if over Brake Shoes DISASSEMBLY Remove the springs and brake shoes. Springs Brake Arm Brake Cam Remove the brake arm bolt to remove the brake arm.
  • Page 142 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 Grease ASSEMBLY ＊ Brake Cam • Keep grease off the linings because contaminated brake linings reduce stopping power. • During installation, wipe any excess grease off the brake cam. Grease Springs Brake Lining Brake Cam...
  • Page 143 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 Install the brake arm onto the brake cam, aligning the punch mark on the cam with the scribed line on the arm. Install and tighten the brake arm bolt. Torque: 0.8～1.2kg-m INSTALLATION Install the brake panel and rear wheel in the reverse order of removal.
  • Page 144 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 REAR FORK REMOVAL Remove the rear wheel. Remove the rear shock absorbers. Remove the cover the rear fork pivot nut to remove the pivot and rear fork. Rear Fork Pivot Nut 12-11...
  • Page 145 . REAR WHEEL/BRAKE/SUSPENSION NEXXON 50 Pivot Bushing Remove the drive chain slider and check for wear or damage. ＊ When replacing the rear fork pivot bushings, press in the new bushings to make them flush with the rear fork. INSTALLATION Install the rear fork in the reverse order of removal.

  • Page 146: Hydraulic Brake

    . HYDRAULIC BRAKE NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ HYDRAULIC BRAKE __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 13- 2 TROUBLESHOOTING----------------------------------------------------- 13- 3 BRAKE FLUID CHANGE/AIR BLEED--------------------------------- 13- 4 BRAKE PAD/DISK --------------------------------------------------------- 13- 5 BRAKE MASTER CYLINDER ------------------------------------------- 13- 6 BRAKE CALIPER ---------------------------------------------------------- 13- 9...
  • Page 147 . HYDRAULIC BRAKE NEXXON 50 SCHEMATIC DRAWING 2.5～3.5kg-m 2.4～3.0kg-m 13-1...

  • Page 148: Hydraulic Brake

    . HYDRAULIC BRAKE NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • Drain the brake fluid from the hydraulic brake system before disassembly. • Do not allow any foreign matters entering the brake reservoir when filling the brake reservoir with brake fluid.

  • Page 149: Troubleshooting

    . HYDRAULIC BRAKE NEXXON 50 TROUBLESHOOTING Loose brake lever • Air in hydraulic brake system • Brake fluid level too low • Hydraulic brake system leakage Tight brake lever • Seized piston • Clogged hydraulic brake system • Smooth or worn brake pad Hard braking •...

  • Page 150: Brake Fluid Change/Air Bleed

    . HYDRAULIC BRAKE NEXXON 50 Screws BRAKE FLUID CHANGE/AIR BLEED Place the motorcycle on its main stand on level ground and set the handlebar upright. Remove the two screws attaching the brake fluid reservoir cap. ＊ Use shop towels to cover plastic parts and coated surfaces to avoid damage caused by splash of brake fluid.

  • Page 151: Brake Pad/Disk

    . HYDRAULIC BRAKE NEXXON 50 Bolts BRAKE PAD/DISK BRAKE PAD REPLACEMENT Remove the two bolts attaching the brake caliper holder. ＊ The brake pads can be replaced without removing the brake fluid tube. Remove the brake caliper. Pin Bolts Remove the pad pin bolts and brake pads.

  • Page 152: Brake Master Cylinder

    . HYDRAULIC BRAKE NEXXON 50 BRAKE DISK Measure the brake disk thickness. Service Limit: 3.0mm Measure the brake disk runout. Service Limit: 0.3mm Fluid Tube Bolt BRAKE MASTER CYLINDER REMOVAL Drain the brake fluid from the hydraulic brake system. ＊...
  • Page 153 . HYDRAULIC BRAKE NEXXON 50 DISASSEMBLY Remove the piston rubber cover and snap ring from the brake master cylinder. Snap Ring Pliers Master Cylinder 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.
  • Page 154 . HYDRAULIC BRAKE NEXXON 50 ASSEMBLY Before assembly, apply brake fluid to all removed parts. Install the spring together with the 1st rubber cup. ＊ • During assembly, the master cylinder, main piston and spring must be installed as a unit without exchange.

  • Page 155: Brake Caliper

    . HYDRAULIC BRAKE NEXXON 50 BRAKE CALIPER REMOVAL Remove the brake caliper and brake pad springs. Place a clean container under the brake caliper and disconnect the brake fluid tube from the brake caliper. ＊ Be careful not to splash brake fluid on any coated surfaces.
  • Page 156 . HYDRAULIC BRAKE NEXXON 50 INSPECTION Check each piston for scratches or wear. Measure each piston O.D. with a micrometer gauge. Service Limit: 25.45mm replace if below Check each caliper and caliper cylinder for scratches or wear and measure the caliper cylinder I.D.
  • Page 157 . HYDRAULIC BRAKE NEXXON 50 INSTALLATION Install the brake caliper onto the right front fork and tighten the bolts. Torque: 2.4～3.0kg-m Connect the brake fluid tube to the brake caliper and tighten the fluid tube bolt. Torque: 2.4～3.0kg-m Add the recommended brake fluid into the brake reservoir and bleed air from the brake system.
  • Page 158 . FRAME COVER NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ FRAME COVER __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 14- 2 FRAME COVER------------------------------------------------------------- 14- 3 14-0...
  • Page 159 . FRAME COVER NEXXON 50 SCHEMATIC DRAWING 14-1...

  • Page 160: Frame Cover

    . FRAME COVER NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • The exhaust muffler must be removed when it is cold to avoid burns. • When installing the exhaust muffler, first tighten the exhaust muffler joint lock nuts and then tighten the exhaust muffler hanger lock bolt.
  • Page 161 . FRAME COVER NEXXON 50 Screw FRAME COVERS FRONT COVER REMOVAL Remove the screw on the front cover. Remove the six screws on the back of the front cover. Remove the front cover. The installation sequence is the reverse of removal.
  • Page 162 . FRAME COVER NEXXON 50 MET-IN BOX REMOVAL Battery Cover Screws Open the seat and remove the two screws attaching the battery cover Remove the battery cover. Remove the battery and C.D.I. Remove the two nuts and three bolt attaching the met-in box.
  • Page 163 . FRAME COVER NEXXON 50 right and left side covers. Side Cover Remove the right and left side covers. Disconnect the seat lock wire. Remove the frame body cover. The installation sequence is the reverse of remove . ＊ During removal, do not pull the joint claws forcedly to avoid damage.
  • Page 164 . FRAME COVER NEXXON 50 Ring Decorative Bolts LEG SHIELD REMOVAL Remove the front center cover Remove the leg shield bolt. Remove the ignition switch decorative ring Remove the leg shield. The installation sequence is the reverse of remove Leg Shield...

  • Page 165: Ignition System

    . IGNITION SYSTEM NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ IGNITION SYSTEM __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 15- 2 TROUBLESHOOTING----------------------------------------------------- 15- 3 IGNITION COIL------------------------------------------------------------- 15- 4 CDI UNIT--------------------------------------------------------------------- 15- 5 PULSER COIL/EXCITER COIL------------------------------------------ 15- 6 15-0...
  • Page 166 . IGNITION SYSTEM NEXXON 50 Ignition Switch CDI Unit Wire Harness A.C. Generator Pulser Coil Wire Connector Ignition Coil 15-1...

  • Page 167: Ignition System

    . IGNITION SYSTEM NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • Inspect the ignition system according to the sequence specified in the Troubleshooting 15-2. • The ignition system has an electrical auto aligner in the CDI unit, so the ignition timing is not adjustable.

  • Page 168: Troubleshooting

    . IGNITION SYSTEM NEXXON 50 TROUBLESHOOTING Engine stalls immediately after it starts • Weak spark • Improper ignition timing • Faulty CDI unit No spark at plug • Faulty ignition switch • Poorly connected, broken or shorted wire −Between pulser coil, CDI unit and ignition coil −Between exciter coil and CDI unit...

  • Page 169: Ignition Coil

    . IGNITION SYSTEM NEXXON 50 IGNITION COIL CONTINUITY TEST ＊ This test is to inspect the continuity of ignition coil. Remove the right decorative cover. Measure the resistance between the ignition coil primary coil terminals. Resistance(20℃): 0.1～0.3Ω Ignition Coil Measure the secondary coil resistance between the spark plrg cap and the primary coil terminal as Figure A shown.

  • Page 170: Cdi Unit

    . IGNITION SYSTEM NEXXON 50 CDI Coupler CDI UNIT REMOVAL Remove the left side cover (page 14-3). Disconnect the CDI coupler and remove the CDI unit. CDI Unit INSPECTION Black/Red Black/Yellow Measure the resistance between the CDI unit terminals. Replace the CDI unit if the readings are not within the specifications in the table below.
  • Page 171 . IGNITION SYSTEM NEXXON 50 Black/Yellow EXCITER COIL/PULSER COIL INSPECTION ＊ This test is performed with the stator installed in the engine. Remove the met-im box. Disconnect the A.C. generator wire connector. Measure the pulser coil resistance between the blue/yellow wire and ground.

  • Page 172: Charging System

    . CHARGING SYSTEM NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ CHARGING SYSTEM __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 16- 2 TROUBLESHOOTING----------------------------------------------------- 16- 3 BATTERY -------------------------------------------------------------------- 16- 4 PERFORMANCE TEST---------------------------------------------------- 16- 5 A.C. GENERATOR --------------------------------------------------------- 16- 5 REGULATOR/RECTIFIER------------------------------------------------ 16- 6 16-0...
  • Page 173 . CHARGING SYSTEM NEXXON 50 Battery Fuse Regulator/Rectifier Starter Relay Battery Positive Cable 16-1...

  • Page 174: Charging System

    . CHARGING SYSTEM NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • The battery is a MF battery which needs no refilling of distilled water. • Do not quick charge the battery. Be sure to use a MF battery charger and the battery temperature should not exceed 45℃.

  • Page 175: Troubleshooting

    . CHARGING SYSTEM NEXXON 50 TROUBLESHOOTING No power • Dead battery • Fuse burned out • Disconnected battery cable • Faulty ignition switch Low power • Weak battery • Loose battery connection (terminal) • Charging system failure • Faulty regulator/rectifier Intermittent power •...

  • Page 176: Battery

    . CHARGING SYSTEM NEXXON 50 Terminal (+) Battery BATTERY REMOVAL Open the seat and battery cover. First disconnect the battery negative cable and then the positive cable. Remove the battery. When disconnecting the battery positive (+) cable, do not touch the frame with tool;...

  • Page 177: Performance Test

    . CHARGING SYSTEM NEXXON 50 PERFORMANCE TEST Perform this test with a fully charged battery. Start and warm up the engine for 10 minutes. Connect the battery positive cable to the ammeter positive probe and the battery negative cable to the ammeter negative probe.

  • Page 178: Regulator/Rectifier

    . CHARGING SYSTEM NEXXON 50 REGULATOR/RECTIFIER REMOVAL Remove the front cover(page 14-4). Remove the regulator/rectifier lock nut and disconnect the regulator/rectifier wire coupler. Measure the resistances between the regulator/rectifier wire terminals. Replace the regulator/rectifier if the readings are not within the specifications in the table below.

  • Page 179: Starting System

    . STARTING SYSTEM NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ STARTING SYSTEM __________________________________________________________________________________ STARTING SYSTEM DIAGRAM --------------------------------------- 17- 1 SERVICE INFORMATION------------------------------------------------ 17- 2 TROUBLESHOOTING----------------------------------------------------- 17- 2 STARTER MOTOR --------------------------------------------------------- 17- 3 STARTER RELAY---------------------------------------------------------- 17- 5 17-0...
  • Page 180 . STARTING SYSTEM NEXXON 50 STARTING SYSTEM DIAGRAM Battery Starter Motor Starter Relay 12V5AH 17-1...

  • Page 181: Starting System

    . STARTING SYSTEM NEXXON 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • The removal of starter motor can be accomplished with the engine installed in the frame. • Refer to Section 8-3 for the removal of starter clutch. • When connecting the starting system wires, connect them securely to avoid hard starting due to poor connection.

  • Page 182: Starter Motor

    . STARTING SYSTEM NEXXON 50 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 183 . STARTING SYSTEM NEXXON 50 Continuity Check for continuity from the cable terminal to the brush holder and from the cable terminal to the brush. Cable terminal and brush holder No continuity: normal Cable terminal and brush Continuity: normal No Continuity Inspect the brushes for wear or damage.

  • Page 184: Starter Relay

    . STARTING SYSTEM NEXXON 50 Starter Relay STARTER RELAY INSPECTION Remove the left side cover. Disconnect the starter relay coupler and then remove the starter relay. Connect the starter relay yellow/red terminal to the 12V battery positive (+) terminal and the relay green terminal to the battery negative (-) terminal.

  • Page 185: Lights/Instruments/Switches/ Horn/Fuel Unit

    . LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT NEXXON 50 __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT __________________________________________________________________________________ SERVICE INFORMATION------------------------------------------------ 18- 1 TROUBLESHOOTING----------------------------------------------------- 18- 1 HEADLIGHT/INSTRUMENT -------------------------------------------- 18- 2 TURN SIGNAL LIGHT ---------------------------------------------------- 18- 3 STOP LIGHT/TAIL LIGHT ----------------------------------------------- 18- 3 IGNITION SWITCH -------------------------------------------------------- 18- 3...

  • Page 186: Service Information

    . LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT NEXXON 125 SERVICE INFORMATION GENERAL INSTRUCTIONS • All plastic plugs have locking tabs that must be released before disconnecting. • An electric tester must be used for checking the continuity between two points. The electric tester also contains a voltmeter which can be used to measure voltage. •...
  • Page 187 . LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT NEXXON 50 HEADLIGHT REMOVAL Remove the handlebar front cover (page 14- Remove the headlight unit and disconnect the headlight wire coupler. Remove the headlight bulb and bulb socket. Check the bulb for damage and replace with a new one if necessary.

  • Page 188: Ignition Switch

    . LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT NEXXON 125 Screws TURN SIGNAL LIGHT Remove the two turn signal shell screws and turn signal shell. Remove the two turn signal bulbs. The installation sequence is the reverse of removal. Turn Signal Shell Turn Signal Bulb Taillight Shell STOP LIGHT/TAILLIGHT Remove the two taillight shell screws and...
  • Page 189 . LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT NEXXON 50 STARTER BUTTON Disconnect the right switch wire coupler. Check for continuity between the black and yellow/red wires. Color Green Yellow/Red Position FREE ○ ○ PUSH Starter Button HORN BUTTON Remove the decorative covers under the fuel tank.

  • Page 190: Handlebar Switches

    . LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT NEXXON 125 HANDLEBAR SWITCHES FRONT STOP SWITCH Disconnect the front stop switch wire coupler. Check for continuity between the front stop switch wires. Brake lever applied: There is continuity. Brake lever released: There is no continuity. Front Stop Switch REAR STOP SWITCH Remove the right side cover.
  • Page 191 . LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT NEXXON 50 Passing Switch Dimmer Switch DIMMER SWITCH Disconnect the dimmer switch wire coupler. Check for continuity between the dimmer switch wires. Color White/Blue White Blue Position ○ ○ ○ ○ ○ ○ ○ PASSING SWITCH...
  • Page 192 . LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT NEXXON 125 FUEL UNIT ＊ No Smoking！ REMOVAL Remove the seat.(Refer to 4-10.) Disconnect the fuel unit wire connectors. ＊ Do not damage the fuel unit wire. Remove the fuel unit. ＊ Be careful not to bend or damage the fuel unit float arm.
  • Page 193 . LIGHTS/INSTRUMENTS/SWITCHES/HORN/ FUEL UNIT NEXXON 50 Flange Groove INSTALLATION The installation sequence is the reverse of removal. ＊ Align the groove on the fuel unit with the flange on the fuel tank. 18-8...

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