E-TON VIPER 50 ST Service Manual
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E-TON VIPER 50 ST Service Manual

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SERVICE MANUAL

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  • Page 1 SERVICE MANUAL...

  • Page 2: Table Of Contents

    CONTENTS 1. INFORMATION 2. MAINTENANCE 3. ENGINE REMOVAL AND INSTALLATION 4. ENGINE FUEL SYSTEM 5. ENGINE LUBRICATION AND COOLING SYSTEM 6. ENGINE COMBUSTION SYSTEM 7. TRANSMISSION SYSTEM 8. STEERING SYSTEM 9. FRONT WHEEL SYSTEM 10. REAR WHEEL SYSTEM 11. FENDERS AND EXHAUST PIPE 12.
  • Page 3 1. INFORMATION SAFTY SERIAL NUMBER NOTES TORQUE VALUE SPECIFICATION 1.1 SAFETY GASOLINE Gasoline is extremely flammable and is explosive under certain condition. Do not smoke or allow sparks or flames in your work area. CARBON MONOXIDE ● Never run the engine in a closed area. The exhaust contains poisonous carbon monoxide gas that may cause loss of consciousness and lead to death.
  • Page 4 1.3 SPECIFICATION ENGINE (for Viper & Yukon in this service manual) Type Two cycle air cooled Displacement 49.3 c.c. 40.0X39.2mm Bore and Stroke 6.8:1 Compression ratio Maximum Torque (Nm/rpm) 4.5 Nm/6000rpm Maximum Power (ps/rpm) 3.8 ps/6000rpm Carburetor Piston type Ignition Capacitor Discharge Starting Electric and kick starter...
  • Page 5 1.4 SERIAL NUMBER (For Viper / Yukon in this service manual) EXL-50 EXL-50 The frame serial number is stamped on the front of the frame. The engine serial number is stamped on the left side of the crankcase. Frame serial number Engine serial number...
  • Page 6 .5 TORQUE VALUES (For EXL 50 in this service manual) STANDARD ● 5 mm bolt and nut 5 N.m (3.5 lbf.ft) 10 N.m (7.2 lbf.ft) ● 6 mm bolt and nut 22 N.m (16 lbf.ft) ● 8 mm bolt and nut 35 N.m (25 lbf.ft) ●10 mm bolt and nut 55 N.m (40 lbf.ft)

  • Page 7: Maintenance

    2. MAINTENANCE 2.1 MAINTENANCE DATA 2.8 IDLE SPEED 2.2 MAINTENANCE SCHEDULE 2.9 DRIVE CHAIN 2.3 FUEL TUBE 2.10 BRAKE SYSTEM 2.4 THROTTLE OPERATION 2.11 WHEELS AND TIRES 2.5 THROTTLE CABLE ADJUSTMENT 2.12 STEERING SYSTEM 2.6 AIR CLEANER 2.13 TOE-IN 2.7 SPARK PLUG 2.14 GEAR OIL 2.1 MAINTENANCE DATA SPECIFICATION...
  • Page 8 2.3 FUEL TUBE Inspect the fuel lines for deterioration, damage or leakage and replace if necessary. 2.4 THROTTLE OPERATION Inspect for smooth throttle lever full opening and automatic full closing in all steering positions. Inspect if there is no deterioration, damage or kinking in the throttle cable, replace it if necessary.
  • Page 9 2.6 AIR CLEANER Unscrew the air cleaner cover screws. Pull out the air filter element from the air cleaner case. Wash the element in non-flammable solvent, squeeze out the solvent thoroughly. Let it dry. Soak the filter element in gear oil and then squeeze out the excess oil.
  • Page 10 Adjust the chain slack. Loose the lock bolts (4 pcs) then adjust the drive chain slack by turn the adjusting nut. Tighten the four lock bolts. When the drive chain becomes very dirty, it should be removed, cleaned and lubricated by specify lubricator. Using commercial chain lubricant to lubricate the drive chain.
  • Page 11 Inspect the rear brake lever and cable for excessive play or other damage. Replace or repair if necessary. Measure the free play of the rear brake lever at the end of The standard is 15-25 mm. the lever. BRAKE SHOE WEAR FRONT BRAKE Release the front wheel and inspect the brake lining thickness.
  • Page 12 STEERING SHAFT HOLDER BUSHING Remove the front fender first. Remove the steering shaft holder and check the steering shaft bushing for wears or damage. If the bushing is worn or damaged, change a new one. Grease the steering shaft bushing and install the parts in the reverse order of removal.
  • Page 13 2.14 GEAR OIL Gear oil needs to be changed every year. There is a gear oil release bolt at the rear of engine. Unscrew this release bolt and can let the dirty oil flow out. The re-add oil hole is on the engine case beside gearbox.

  • Page 14: Engine Removal And Installation

    3. ENGINE REMOVAL AND INSTALLATION 3.1 SERVICE INFORMATION 3.3 ENGINE INSTALLATION 3.2 ENGINE REMOVAL 3.1 ENGINE SHALL BE REMOVED IN THE CONDITIONS OF NECESSARY REPAIRMENT OR ADJUSTMENT TO THE TRANSMISSION AND COMBUSTION SYSTEM ONLY 3.2 ENGINE REMOVAL Remove the seat and rear fender. (Chapter 11) Remove the spark plug cap from the spark plug.
  • Page 15 3.3 ENGINE INSTALLATION Engine installation is essentially the reverse order of removal. The torque of engine hanger bolt is 24-30 Nm Route the wires and cable in reverse order properly.
  • Page 16 ★ U ADJUSTMENT NPROPER TO THE POORLY DLE SPEED SCREW ★ I GNITION MALFUNCTION ★ F AIR MIXTURE RATIO NO GOOD ★ A IR CLEANER DIRTY ★ I NSULATOR LEAKS ★ F UEL TANK CAP BREATHING HOLE CLOGGED ★ EAN MIXTURE FUEL JET CARBURETOR CLOGGED ★...

  • Page 17: Engine Fuel System

    4. ENGINE FUEL SYSTEM 4.1 FUEL TANK 4.2 CARBURETOR 4.1 FUEL TANK REMOVAL Remove the seat and rear fender. Disconnect the fuel line from the carburetor. Remove the fuel tank cap and front fender. Unscrew the fuel tank fixed bolts. Note: Keep gasoline away from flames or sparks.
  • Page 18 DISASSEMBLY Unscrew the float chamber screws and remove carburetor chamber. carburetor chamber Disassembly the float and float needle valve. Inspect the seat of the float needle valve for wear or damage. Disassembly the slow jet, main jet, throttle adjusting throttle adjusting screw screw and air flow adjusts screw.
  • Page 19 ASSEMBLY Clean all parts in solvent and blow it dry with compressed air. Assembly is essentially the reverse order of disassembly. THROTTLE VALVE ASSEMBLY Install the needle clip on the jet needle. Install the jet needle into the throttle valve. Assembly the throttle cable, spring and the throttle valve.

  • Page 20: Engine Lubrication And Cooling System

    5. ENGINE LUBRICATION AND COOLING SYSTEM 5.1 ENGINE LUBRICATION SYSTEM 5.4 COOLING SYSTEM 5.2 CAUTION 5.5 TROUBLESHOOTING 5.3 OIL PUMP 5.1 ENGINE LUBRICATION SYSTEM The engine drives the pump gears of oil pump crankshaft. Pump gears rotate the plunger shaft in oil pump.
  • Page 21 5.5 TROUBLESHOOTING NO ENOUGH OIL SUPPLY TO ENGINE THE OIL LEVEL IN OIL TANK IS TOO LOW. ★ OIL TUBES WERE NOT FIXED WELL. ★ OIL HAS LEAKAGED FROM TUBE ENDS. ★ OIL TUBES WERE BROKEN. ★ OIL TUBES WERE CLOGGED. ★...

  • Page 22: Engine Combustion System

    6. ENGINE COMBUSTION SYSTEM 11.1 TROUBLESHOOTING 11.3 CYLINDER AND PISTON INSPECTION 11.2 CYLINDER AND PISTON REMOVAL 11.4 INSTALLATION 6.1 TROUBLESHOOTING LOW COMPRESSION ★ CYLINDER HEAD HEAD GASKET LEAKING OR DAMAGED WARPED OR CRACKED CYLINDER HEAD CYLINDER OR PISTON RINGS WORN OUT ★...
  • Page 23 6.2 CYLINDER AND PISTON REMOVAL Remove the seat and rear fender. Remove the exhaust pipe. Remove the spark plug cap. Disconnect the wire. Drag out the engine. Disassembly the air cleaner and carburetor. Remove the intake pipe mounting bolts. Remove the cylinder bolt nuts. Remove the cylinder head.
  • Page 24 Check the cylinder head mating surface for warp with a straight edge and feeler gauge. Service limit: 0.10 mm Insert each piston ring into the cylinder, and measure the end gap. Service limit: 0.5 mm Measure the clearance between ring and groove. Service limit: 0.09 mm Measure the piston outer diameter at 10 mm high from the skirt’s bottom.
  • Page 25 Measure the piston pin bore, and the piston pin outer diameter. Pin outer diameter service limit: 9.96 mm Pin bore service limit: 10.04 mm Measure the connecting rod small end inner diameter with a small bore diameter gauge. Service limit: 14.06 mm 6.4 INSTALLATION Install the piston rings with the marks facing up.
  • Page 26 Apply some oil to inside of the connecting rod small end. Install the piston, piston pin and clip. Install the piston with the arrow mark facing the exhaust pipe. Do not align the piston pin clip end gap with the piston cutout. Install a new cylinder gasket.

  • Page 27: Transmission System

    7. TRANSMISSION SYSTEM 7.1 TROUBLE SHOOTING 7.6 GEAR BOX 7.2 THE PARTS DRAWING OF TRANSMISSION 7.7 ELECTRIC SELF-STARTER MECHANISM SYSTEM 7.8 KICK STARTER 7.3 SHIFT MECHANISM (INCLUDE C.D.I) 7.9 DISASSEMBLY AND CHECK OF C.V.T. 7.4 AUTOMATIC CONTINUOUS VARIABLE SYSTEM TRANSMISSION 7.5 CONTINUOUS VARIABLE TRANSMISSION 7.1 TROUBLESHOOTING ABNORMALLY ACT IN SHIFTING AND CAN’T RESET...
  • Page 28 Shift Mechanism Gear Box For...
  • Page 29 7.3 SHIFT MECHANISM Sensor Inspect wire for break or damage and check contact. Measure sensor dimension as fig-1 after unscrew sensor. fig-1 If length is below 30mm, it must be replaced. Sensor N2 Smear with loctite 5699 and screw with torque 25 kgf-cm in assembly.
  • Page 30 Shift Motor Check shift motor whether it’s action is normal as follow data: Brush Disassembly mission side cover, parts of shift mechanism and mission cover. Get seal and bearing after disassembly shift motor of mission cover. Seal Bearing Check seal and for wear or fatigue. Replace it if necessary.
  • Page 31 Driven Pulley Because the revolving radius of V-Belt at the Drive End is enlarged, the Face Comp Movable Drive is squeezed out by the V-Belt at the Driven End to shorten the revolving radius. There is a Torque Cam on the Movable Drive Face. Torque Cam is loaded from outside.
  • Page 32 ELECTRIC SELF-STARTER MECHANISM KICK STARTER 7.8 KICK STARTER This kick-starter arm is on the left side of engine. When the kick-starter arm is kicked, the gear of start shaft will drive the kick-starter to revolve the crankshaft to start the engine. After the engine is started, the kick-started will stop transfer the power to the kick-starter driven gear.
  • Page 33 8. STEERING SYSTEM 8.1 THE PARTS DRAWING OF STEERING SYSTEM 8.3 HANDLEBAR 8.2 TROUBLESHOOTING 8.4 STEERING SYSTEM 8.1 THE PARTS DRAWING OF STEERING SYSTEM 8.2 TROUBLESHOOTING HARD STEERING ★ Faulty tire ★ Steering shaft holder too tight ★ Insufficient tire pressure ★...
  • Page 34 FRONT SUSPENSION NOISE ¡ ¹ Loose front suspension fasteners ¡ ¹ Binding suspension link HARD SUSPENSION ¡ ¹ Faulty front swing arm bushings ¡ ¹ Improperly installed front swing arms ¡ ¹ Bent front shock absorber swing rod SOFT SUSPENSION ¡...
  • Page 35 Remove the bolts attaching the handlebar upper holder. Remove the handlebar. I INSTALLATION Put the handlebar on the lower holders. Make sure the handlebar punch mark match with the top end of the handlebar lower holders. Install the handlebar upper holders with the L or R marks facing forward.
  • Page 36 Aligning the split line of the throttle housing and holder with the punch mark. Tighten the screw securely 8.4 THROTTLE HOUSING DISASSEMBLY Unscrew the screws on the throttle housing cover. Remove throttle housing cover and gasket. Disconnect throttle cable from the throttle arm and remove from the throttle housing.
  • Page 37 Tie-rod Inspection Inspect the tie-rod for damage or bending. Inspect the ball joint rubbers for damage, wear or deterioration. Turn the ball joints with fingers. The ball joints should turn smoothly and quietly. Kingpin Inspection Inspect the kingpin for damage or cracks. Steering Shaft Removal Remove the handle bar cover and handle bar.
  • Page 38 Steering Shaft Inspection Inspect the steering shaft for damage or cracks. Installation of Steering Shaft Apply grease to the holder. Install the holder and oil seal tighten with the nuts. Torque: 33 N.m (24 lbf-ft) Install the steering shaft nut and tighten it. This nut is under this steering shaft.

  • Page 39: Front Wheel System

    9. FRONT WHEEL SYSTEM 9.1 PARTS DRAWING 9.2 TROUBLESHOOTING 9.3 FRONT WHEEL 9.4 FRONT BRAKES 9.1 PARTS DRAWING FRONT WHEEL FRONT BRAKE 9.2 TROUBLESHOOTING HARD STEERING ★ Faulty tire ★ Insufficient tire pressure FRONT WHEEL WOBBLING ★ Faulty tire ★ Worn front brake drum bearing ★...
  • Page 40 9.3 FRONT WHEELS REMOVAL Raise the front wheels off the ground by placing a jack or other support under the frame. Remove the front wheel nuts, washer and wheels. INSTALLATION Install and tighten the four-wheel castle nuts Torque: 40-60 N.m (30-45 lbf.ft) Remember put a cotter pin in the castle nut.
  • Page 41 Turn the inner race of each bearing with fingers. The bearings should turn smoothly and quietly. If the race does not turn smoothly or quietly, remove and discard the bearings. BRAKE PANEL REMOVAL Disconnect the brake cable from the brake arm. Remove the brake panel from the knuckle.
  • Page 42 Install the brake arm on the cam by aligning the punch mark and the groove on the cam. Tighten the brake arm bolt and nut. Torque: 4-7 N.m Install the return spring. Install the brake panel on the knuckle. Connect the brake cable to the brake arm. Install the brake arm cover.

  • Page 43: Rear Wheel System

    10. REAR WHEEL AND BRAKE SYSTEM 10.1 PARTS DRAWING DRIVE MECHANISM 10.3 10.2 TROUBLESHOOTING HYFRAULIC DISC BRAKE SYSTEM 10.4 10.1 THE PARTS DRAWING OF REAR WHEEL SYSTEM FOR ATV RXL70 AND RXL50M FOR RXL 50/70/90/90R...
  • Page 44 10.2 TROUBLESHOOTING BAD BRAKE PERFORMANCE BRAKE SHOES ARE WORN ★ ★ BAD BRAKE ADJUSTMENT ★ BRAKE LININGS ARE OILY, GREASY OR DIRTY ★ BRAKE DRUMS ARE WORN ★ BRAKE ARM SETTING IS IMPROPERLY ENGAGE AXLE IS NOT TIGHTENED WELL VIBRATION OR WOBBLE ★...
  • Page 45 Disassembly the driven sprocket, axle and sprocket collar. Check the driven sprocket for damage or wear. Let the rear axle lie in V-blocks and check the run out. The run out limit is 0.5 mm Check the turning of bearing with fingers. The bearings should turn smoothly and quietly.
  • Page 46 Assembly the wheel. Tighten the rear axle nut with 60-80 N.m. Install a new cotter pin. Adjust rear brake level free play. Adjust chain slack. 10.4 HYFRAULIC DISC BRAKE SYSTEM To replace brake disc To replace brake disc Remove the rear left tire Unscrew the two bolts shown on the photo and remove caliper Unscrew the rear wheel axle nut and then remove...
  • Page 47 Unscrew bolts and remove the brake disc Check the thickness of disc and replace a new one if the thickness less than 3mm TO REPLACE THE BRAKE SHOE Remove the rear left tire Unscrew the two bolts shown on the photo and remove caliper Press the plate to the end...
  • Page 48 Remove the brake shoe as shown Check the thickness of brake shoe and replace a new one if the thickness less than 1mm. Press the piston to the end prior to installation of brake shoe Piston TO REPLACE THE BRAKE HYDRAULIC OIL Unscrew the bolts and open the cover.
  • Page 49 Unscrew the bolt and drain out the used oil drain. Fasten the bolt after the used oil being drained out completely. (Dot 3 or Dot 4) Add the brake oil Keep oil level at least half of the cup to avoid air gets into brake system, such like caliper and tube Unscrew the bolt to vent air from brake system.
  • Page 50 Fill the brake oil to the level shown on the cup when no air comes out Assemble the cover...

  • Page 51: Fenders And Exhaust Pipe

    11. FENDERS AND EXHAUST PIPE 11.1 FENDRES DRAWING 11.4 CENTRAL-REAR-TRIM REMOVAL 11.2 REAR FENDERS REMOVAL 11.5 FRONT FENDER REMOVAL 11.3 FRONT-TRIM REMOVAL 11.6 EXHAUST PIPE REMOVAL 11.1 FENDERS DRAWING Yukon Viper EXL-50 EXL-50 EXHAUST PIPE (For all serials) For E-MARK...
  • Page 52 11.2 REAR FENDERS REMOVAL Pull the “Seat Release Bar” to take off the seat. This seat release bar is under the right side of the rear fender. Procedures of remove the rear fender: Remove the rear rack. Unscrew the two bolts which connect the front fender and rear fender.
  • Page 53 There are two screws on the top of seat compartment. Please remove them. Then there are two screws on side of the tail. Finally, you must remove the screws on the footrest. 11.3 FRONT-TRIM REMOVAL Unscrew the two screws just below the headlight of central-front-trim.
  • Page 54 Yukon (Viper. St) 11.4 CENTRAL-REAR-TRIM REMOVAL Remove the fuel tank cap. Remove the central-rear-trim two mounting bolts from the fuel tank. Pull the central-rear-trim up ward. 11.5 FRONT FENDER REMOVAL After remove the rear fender, central-front-trim and central-rear-trim, remove the two front fender mounting bolts from front frame.
  • Page 55 Remove the mounting bolts and nuts from the front fender and footrest plate. (Viper. St) Please remove the two screws on the top of the headlight. Then you can see there is a screw on the tip of the vehicle. Please remove it.
  • Page 56 11.6EXHAUST PIPE REMOVAL You must wait at least 15 minutes after turn off the engine. You need remove the seat, rear fender and footrest plate, before you take off the exhaust pipe. Unscrew the two exhaust pipe bolts that fixed with engine. NOTE¡...

  • Page 57: Electrical System

    12. ELECTRICAL SYSTEM 12.1 TROUBLESHOOTING 12.5 CHARGING 12.2 IGNITION COIL 12.6 ELECTRIC STARTER 12.3 BATTERY CAUTION 12.7 WIRING DIAGRAMS 12.4 BATTERY INSPECTION 12.8 SPEEDOMETER AND FUEL METER 12.9 WIRING DIAGRAM 12.1 TROUBLESHOOTING ENGINE STARTS BUT STOPS ★ IMPROPER IGNITION TIMING ★...
  • Page 58 12.2 IGNITION COIL Remove the spark plug cap from the spark plug Disconnect the ignition coil primary wire. Measure the primary coil resistance. STANDARD: 0.1 - 0.3Ω(20℃) Measure the secondary coil resistance with the spark plug cap in place. STANDARD : 7.4 – 12 kΩ(20℃) IGNITION TIMING The ignition advance is 15°±...
  • Page 59 12.4 BATTERY INSPECTION Battery is under the seat, you can see this battery from the left side. Measure the battery voltage using a voltmeter. VOLTAGE: Fully charged: 13.1 V Undercharged: Below 12.0 V BATTERY REMOVAL Remove the battery holder bolt nuts. Disconnect the negative cable and then the position cable and remove the battery.
  • Page 60 TROUBLESHOOTING Starter Motor Turns Slowly Weak battery. Poorly connected starter motor cable. Failed starter motor. Poorly connected battery ground cable. Starter Motor Not Turn Engine stop switch at “off “position. Gearshift bar is not at neutral position. Check for a blown fuse near battery. Make sure that the battery is fully charged and in good condition.
  • Page 61 TAILLIGHT Install the remove parts in the reverse order of remova Yukon For (Viper.St EXL-50) For( EXL-50) 12.8 SPEED METER AND FUEL METER PARTS DRAWING Yukon Picture of right side is for EXL-50 For Viper. EXL-50...
  • Page 62 REMOVAL THE HEADLIGHT PHOTOGRAPH--EXL 150 (2004 two-passengers) EXL 150(Viper. St) have another shape but its cables position are the same as EXL 150(2004 two-passenger) FUEL ELECTRICAL SPEEDMETER METER CABLE METER CABLE METER METER CABLE SENSOR...
  • Page 63 12.9 WIRING DIAGRAM This diagram is for Viper. St EXL-50...
  • Page 64 Yukon EXL-50 This diagram is for...
  • Page 65 13.TROUBLESHOOTING 13.1 ENGINE DOES NOT START 13.4 LOSS POWER 13.2 POOR PERFORMANCE AT LOW AND IDLE SPEEDS 13.5 POOR HANDLING 13.3 POOR PERFORMANCE AT HIGH SPEED 13.1 ENGINE DOES NOT START POSSSIBLE REASON N.G. ★ No fuel In fuel tank CHECK FUEL FLOW TO CARBURETOR ★...
  • Page 66 13.2 POOR PERFORMANCE AT LOW AND IDLE SPEEDS POSSIBLE REASON N.G. ★ Faulty CDI unit or pulse generator CHECK IGNITION TIMING O.K. CHECK carburetor N.G. ★ Improperly adjusted air screw AIR SCREW ADJUSTMENT ★ Deteriorated insulator o-ring CHECK FOR LEAKING ★...
  • Page 67 13.4 LOSS POWER POSSIBLE REASON RAISE WHEELS OFF GROUND DOES NOT SPIN FREELY ★ Brake dragging AND SPIN BY HAND ★ Drive chain too tight ★ Damaged wheel bearing SPIN FREELY ★ Wheel bearing needs lubrication PESSURE LOW CHECK TIRE ★...
  • Page 68 13.5 POOR HANDLING POSSIBLE REASON STEERING IS HEAVY ★ Damaged steering bearing ★ Damaged steering shaft bushing ONE WHEEL IS WOBBLING Bent rim ★ ★ Improperly installed wheel hub ★ Excessive wheel bearing play ★ Bent swingarm ★ Bent frame ★...

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