Eton VIPER 50 SERVICE MANUAL

SER VICE MANUAL

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. ELECTRICAL SYSTEM

13. TROUBLE SHOOTING

1. INFORMATION

1.1 SAFTY

1.2 NOTES

1.3 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.

1.4 SERIAL NUMBER

1.5 TORQUE VALUE

●

BATTERY ELECTROLYTE

The battery electrolyte contains sulfuric acid. Protect your eyes, skin and

clothing. If you contact it, flush thoroughly with water and call a doctor if electrolyte

gets in your eyes.

● HOT PARTS

Engine and exhaust pipe become very hot and remain hot for one hour after the

engine is run. Wear insulated gloves before handling these parts.

● USED ENGINE/GEAR OIL

Used engine oil and gear oil may cause skin disease if repeatedly contact with

the skin for long periods.

Keep out of reach of children.

1.2 NOTES

All information, illustrations, directions and specifications included in this publication are base on the latest

product information available at the time of approval for printing.

JI-EE Dynamic Technology Industry Co., Ltd. reserves the right to make changes at any time without notice

and without incurring any obligation whatever.

No part of this publication may be reproduced without written permission.

2

1.3 SPECIFICATION ENGINE

Vip

X

r

p

(for Viper

&Yukon

ST

in this service manual)

ST

Type Two cycle air cooled
Displacement 49.3 c.c.

40.0

Bore and Stroke
Compression ratio 6.8:1

Maximum Torque (Nm/rpm)

Maximum Power (ps/rpm)

4.5 Nm/6000

3.8 ps/6000rpm

Carburetor Piston type
Ignition Capacitor Discharge
Starting Electric and kick starter
Lubrication Forced pressure and wet sump
Transmission Automatic (C.V.T. V-belt) Fr Neut .Rev

39.2mm

m

er

EXL-50

Yukon

EXL-50

CHASSIS
Overall Length 1670 mm 1750 mm
Overall Width 940 mm 1010 mm
Overall Height 1040 mm 1065 mm
Seat Height 760 mm 760 mm
Wheel base 1110 mm 1115 mm
Ground Clearance 120 mm 120 mm
Dry Weight 152 kg 152 kg
Fuel Tank Capacity 4.5 Liters 4.5 Liters

SUSPENSION
Front
Rear
BRAKES
Front
Rear
TIRES
Front

Rear 20/10-9
PRESSURE 【psi (0.23 kgf/cm

Front
Rear

Viper

EXL-50 Yukon

ST

ST

Single A-arm / Adjustable Shocks

Swing Arm / Adjustable Shock

Dual Mechanical drum

Hydraulic Disc

20/6-10

2

)】
12(0.8) 12(0.8)
12(0.8) 12(0.8)

EXL-50

COLORING

Specifications subject to change without notice.

3

1.4 SERIAL NUMBER
(For Viper

EXL-50 / YukonST EXL-50 in this service manual)

ST

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

4

.5 TORQUE VALUES

(For EXL 50 in this service manual)

STANDARD

● 5 mm bolt and nut

● 6 mm bolt and nut

● 8 mm bolt and nut

●10 mm bolt and nut

●12 mm bolt and nut

ENGINE

● Cylinder head nut

● Spark plug

● Cylinder head bolt

● Alternator bolt

FRAME

● Handlebar upper holder bolt

● Throttle housing cover screw

● Steering shaft nut

● Steering shaft holder bolt

5 N.m (3.5 lbf.ft)

10 N.m (7.2 lbf.ft)

22 N.m (16 lbf.ft)

35 N.m (25 lbf.ft)

55 N.m (40 lbf.ft)

28 N.m (20.7 lbf.ft)

12 N.m (8.9 lbf.ft)

20 N.m (14.8 lbf.ft)

8 N.m (5.9 lbf.ft)

24 N.m (17.7 lbf.ft)

4 N.m (2.9 lbf.ft)

50 N.m (36.9 lbf.ft)

33 N.m (24 lbf.ft)

● Wheel rim bolt

● Tie rod lock nut

● King pin nut

● Handlebar lower holder nut

● Front wheel bolt

● Front axle castle nut

● Front brake arm nut

● Rear brake arm nut

● Rear axle castle nut

● Rear wheel bolt

● Exhaust muffler mounting bolt

● Engine hanger bolt

● Rear axle holder bolt

● Swing arm pivot nut

● Rear shock absorber mounting nut

18 N.m (13.3 lbf.ft)

35 N.m (25.8 lbf.ft)

40 N.m (29 lbf.ft)

5

40 N.m (29.5 lbf.ft)

24 N.m (17.7 lbf.ft)

40-60 N.m (30-45 lbf.ft)

4 N.m (3.0 lbf.ft)

7 N.m (5.2 lbf.ft)

40-60 N.m (30-45 lbf.ft)

24 N.m (17.7 lbf.ft)

30 N.m (22.1 lbf.ft)

30 N.m ( 22 lbf.ft)

90 N.m (65 lbf.ft)

90 N.m (65 lbf.ft)

45 N.m (33 lbf.ft)

2. MAINTENANCE

(

)

(Every

)

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

SPARK PLUG:

SPARK PLUG GAP: 0.6-0.7 mm
RECOMMENDED SPARK PLUGS: NGK BPR7HS
THROTTLE LEVER FREE PLAY: 5-10 mm
IDLE SPEED: 1800±100 rpm
BRAKE LEVER FREE PLAY:
DRIVE CHAIN SLACK
FRONT/REAR TIRE PRESSURE MIN 2 psi (12.5kpa)
TOE-IN 5±10 mm

TORQUE VALUES

SPARK PLUG 25-30 N.m
TIE-ROD LOCK NUT 35-43 N.m

ENGINE OIL JASO FC Grade or same degree oil

GEAR LUBRICATION OIL SAE 90

2.2 MAINTENANCE SCHEDULE

The maintenance internals in the follow table is based upon average riding, conditions. Riding in unusually
dusty areas, require more frequent servicing. (For ATV all serial in this service manual)

FUEL LINE
THROTTLE OPERATION
AIR CLEANER
SPARK PLUG
CARBURETOR IDLE SPEED
DRIVE CHAIN
BRAKE SHOE WEAR
BRAKE SYSTEM
NUT, BOLT, FASTENER
WHEEL
STEERING SYSTEM
SUSPENSION SYSTEM
C.V.T. AIR FILTER
GEAR OIL
REVERSE GEAR OIL-RXL90R

Note – I: Inspect and Clean, Adjust, Lubricate or Replace, if necessary

C: Clean L: Lubricate R: Replace

INITIAL SERVICE

First week

I

I

I, L

I
I
I

REGULAR SERVICE

30 operating days

I, L

C

C

I

I
I

I
I
I

15-25 mm
10-25 mm

EVERY YEAR

I

I

I
I

R
R

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.
Check the throttle lever,
of the throttle lever.
Disconnect the throttle cable at the upper end.
Lubricate the cable with commercially lubricant to
prevent premature wear.

free play is 5-10 mm

2.5 THROTTLE CABLE ADJUSTMENT

Slide the rubber cap of the adjuster off the throttle
Housing, loosen the lock nut and adjust the free play
of the throttle lever by turning the adjuster on the throttle
housing. Inspect the free play of the throttle lever.

at the tip

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.
Install the element into air cleaner carefully.

2.7 SPARK PLUG

This spark plug located at the front of the engine.
Disconnect the spark plug cap and unscrew the spark plug.
Check the spark plug electrodes for wearness.
Change a new spark plug if the electrodes and insulator tip
appear unusually fouled or burned.
Discard the spark plug if there is apparent wear or if the
insulator is cracked or chipped.

The spark plug gap shall keep in 0.6-0.7mm.

With the sealing washer attached, thread the spark plug in
by hand to prevent cross threading.

Tighten the spark plug with 25-30 N.m

2.8 IDLE SPEED

Connect an engine speed meter.
Warm up the engine, 10 minutes are enough.
Turn the idle-speed adjust screw on the carburetor
to obtain the idle speed. “Turn in” (clockwise) will get higher
speed. “Turn out” (counter clockwise) will get lower speed.

IDLE SPEED: 1800±100 rpm

2.9 DRIVE CHAIN

Inspect the chain slack.

The standard is 10-25mm.

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.
Clean the drive chain with kerosene and wipe it dry.
Inspect the drive chain for possible wear or damage.
Replace the chain, if it is worn excessively or damaged.

Inspect the sprocket teeth, if it is excessive wear
or damage, replace it.

Inspect the chain-tensioned roller.
Replace it, if necessary.

2.10 BRAKE SYSTEM

Inspect the front brake lever and cable for excessive
play or other damage.
Replace or repair if necessary.
Measure the free play of the brake lever at the end of the
brake lever.

The standard of free play is 15-25 mm.

Inspect the rear brake lever and cable for excessive

or

play
Replace or repair if necessary.
Measure the free play of the rear brake lever at the end of
the

other damage.

lever.

Th

e standard is 15-25 mm.

BRAKE SHOE WEAR
FRONT

Release the front wheel and inspect the brake lining
thickness.

BRAKE

Service Limit: 2.0mm(0.08 inch)

If either lining is worn beyond the service limit, replace
Both brakes shoes.

2.11 WHEELS AND TIRES

Inspect the tire surfaces for cuts, nails or other sharp objects.
Check

the tire surfaces at cold tire condition.

The standard of tire pressure is 1.2±0.3 ps
(0.8 kgf/cm2)

2.12 STEERING SYSTEM

Check the free play of the steering shaft with the front wheels,
turned
When there is excessive play, inspect the tie-rod, kingpin
bushing

straight ahead.

and ball joint.

i.

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.

Torque: steering shaft holder bolt: 33 N.m (24 lbf.ft)

2.13 TOE-IN

Let the vehicle on level ground and the front wheels facing
straight ahead.
Mark the centers of the tires to indicate the axle center
height.
Measure the distance between the marks.

Carefully move the vehicle back, let the wheels have
turned 180 °, so the marks on the tires are aligned
with the axle center height.
Measure the distance between the marks.
Calculate the difference in the front and rear
measurements.

Toe-in: 5±10mm

If the toe-in is out of standard, adjust it by changing
the length of the tie-rods equally by turning the tie-rod
while holding the ball joint.
Tighten the lock nuts.

Torque: 35-43 N.m

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.

3. ENGINE REMOVAL AND INSTALLATION

3.1 SERVICE INFORMATION

3.2 ENGINE REMOVAL

3.3 ENGINE INSTALLATION

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. Remove the exhaust
pipe.
Disconnect the carburetor cable by unscrew two screws on
top of the carburetor.
Take off oil pump cable from the oil pump control plate. Oil
pump is under the right side of engine.

Disconnect the wire connectors. There are three
connectors for carburetor auto-choke, starter motor
and generator respectively.
Remove the drive chain cover. This is under the chain.
Remove the drive chain retaining clip and master link,
and remove the drive chain.

Remove the three engine hanger nuts and bolts.
Remove the engine from the right side of frame.

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.

POORLY

L

EAN MIXTURE

R

ICH MIXTURE

★

UNPROPER

I

DLE SPEED

★

I

GNITION MALFUNCTION

★

F

UEL/AIR MIXTURE RATIO NO GOOD

★

A

IR CLEANER DIRTY

★

I

NSULATOR LEAKS

★

F

UEL TAN K CAP BREATHING HOLE

CLOGGED

★

FUEL JET

★

F

UEL TAN K CAP BREATHING HOLE

CLOGGED

★

F

UEL FILTER CLOGGED

★

F

UEL FLOWS IN THE

UNSMOOTHLY

★

F

LOAT LEVEL IN CARBURETOR TOO

LOW

★

F

LOAT NEEDLE VALVE IN

CARBURETOR FAULTY

★

F

LOAT LEVEL TOO HIGH

★

A

IR DUCT IN CARBURETOR

CLOGGED

★

A

IR CLEANER DIRTY

ADJUSTMENT

SCREW

OF

CARBURETOR CLOGGED

TUBE

TO THE

IS

4. ENGINE FUEL SYSTEM

4.1

FUEL TANK

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.

Wipe up spilled gasoline at once.

4.2

CARBURETOR

4.2 CARBURETOR

REMOVAL
Remove the air cleaner.
Disconnect the fuel line and auto-choke electric wire.
Unscrew the intake pipe mounting bolts at the
carburetor then removes the carburetor.
Note: Turn fuel cup on (off) position

Remove the carburetor cap.
Remove the throttle cable from the throttle valve while
depressing the throttle valve spring.

Remove the needle clip retainer, the jet needle and
needle clip. Inspect the throttle valve and
jet needle surface for wearness, scratches or dirt.

DISASSEMBLY

n

r

r

r

Unscrew the float chamber screws and remove
the 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
screw and air flow adjusts screw.

Inspect all the jets and screws for wear or damage. Clea
the passages and jets with compressed air.

carbureto

throttle adjusting screw

chambe

ai

flow adjusts screw

main jet

slowjet

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.
Align the throttle valve groove with the idle speed adjust
screw and install the carburetor cap to the carburetor.

5.

ENGINE LUBRICATION

AND COOLING SYSTEM

5.1 ENGINE LUBRICATION SYSTEM

5.2 CAUTION

5.3 OIL PUMP

5.4 COOLING SYSTEM

5.5 TROUBLESHOOTING

5.1 ENGINE LUBRICATION SYSTEM

The engine drives the pump gears of oil pump
crankshaft. Pump gears rotate the plunger shaft in oil
pump. This shaft sent the lubricating oil into the crankcase
to mix with the mixture of air-fuel flow evenly.
The oil drops and foam cover the cylinder inner wall,
piston surface and piston rings.

5.2 CAUTION

Having enough oil supply to engine is very important.
If the oil quantity is not enough, this engine will be serious scratched, and then this engine will stop, even
cannot work again.
When this engine is serious scratched, you need to change the piston, piston rings and cylinder together.
Also you need to check the combustion system and lubrication system carefully.

5.3 OIL PUMP

The quantity of oil that deliver out from oil pump increased by the engine speed and the carburetor throttle
open width. Oil pump is under the right side of the engine and connected by a control cable of throttle.

5.4 COOLING SYSTEM

The engine-cooling fan sucks the air.
The cooling fan is on the right side of engine.
The air is forced to flow through cylinder fin and
cylinder head. So, the cylinder and piston will not
over heat.

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.
★ OIL PUMP CANNOT WORK.

ALWAYS INSUFFICIENT OIL LEVEL ★ EXTERNAL OIL LEAKS
IN LUBRICATE OIL TANK ★ WORN CYLINDE HEAD GASKET

★ WORN PISTON RINGS