Page 1
By KWANG YANG Motor Co., Ltd.
First Edition, Dec 2006
All rights reserved. Any reproduction or
unauthorized use without the written permission of
KWANG YANG Motor Co., Ltd.
is expressly prohibited.
T100LA0975
Page 2
PREFACE
This Service Manual describes the
technical features and servicing
procedures for the KYMCO Mongoose
90/70/50-4T/50-2T & MXER
90R/70R/50R-4T/50R-2T.
Section 1 contains the precautions for
all operations stated in this manual.
Read them carefully before starting any
operation.
Section 2 is the removal/installation
procedures for the frame covers which
are subject to higher removal/installation
frequency during maintenance and
servicing operations.
Section 3 describes the inspection/
adjustment procedures, safety rules and
service information for each part,
starting from periodic maintenance.
Sections 4 through 17 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.
KWANG YANG MOTOR CO., LTD.
OVERSEAS SALES DEPARTMENT
OVERSEAS SERVICE SECTION
TABLE OF CONTENTS
GENERAL INFORMATION 1
FRAME COVERS/EXHAUST MUFFLER 2
INSPECTION/ADJUSTMENT 3
LUBRICATION SYSTEM 4
FUEL SYSTEM 5
ENGINE REMOVAL 6
CYLINDER HEAD/VALVES 7
CYLINDER/PISTON 8
DRIVE AND DRIVEN PULLEYS
9
FINAL REDUCTION/TRANSMISSION
SYSTEM
10
CRANKCASE/CRANKSHAFT
11
FRONT WHEEL/FRONT BRAKE/
FRONT SUSPENSION/STEERING
SYSTEM
12
REAR WHEEL /SWING
ARM/HYDRAULIC BRAKE
13
BATTERY/CHARGING SYSTEM/A.C.
GENERATOR
14
IGNITION SYSTEM 15
STARTING SYSTEM 16
BULBS REMOVAL/INSTRUMENT/HORN 17
CHASSIS
ELECTRICAL
EQUIPMENT
ENGINE
The information and contents included in
this manual may be different from the
vehicle in case specifications are changed.
KYMCO reserves the right to make
changes at any time without notice and
without incurring any obligation.
Page 3
1. GENERAL INFORMATION
1-0
1
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
GENERAL INFORMATION
__________________________________________________________________________________
SERIAL NUMBER---------------------------------------------------------- 1- 1
SPECIFICATIONS ---------------------------------------------------------- 1- 2
SERVICE PRECAUTIONS ------------------------------------------------ 1- 6
TORQUE VALUES --------------------------------------------------------- 1-14
SPECIAL TOOLS ----------------------------------------------------------- 1-16
LUBRICATION POINTS -------------------------------------------------- 1-17
CABLE & HARNESS ROUTING ---------------------------------------- 1-20
WIRING DIAGRAMS ------------------------------------------------------ 1-23
TROUBLESHOOTING----------------------------------------------------- 1-28
1
Page 4
1. GENERAL INFORMATION
1-1
SERIAL NUMBER
Location of Engine Serial Numbe
r
(90cc/70cc/50cc-4T)
Location of Frame Serial Numbe
r
Location of Engine Serial Number (50cc-2T)
Page 5
1. GENERAL INFORMATION
1-2
SPECIFICATIONS
Mongoose 90/MXER 90R
Model No. LA20
Overall length 1430 mm (57.2 in)
Overall width 905 mm (36.2 in)
Overall height 910 mm (36.4 in)
Wheel base 965 mm (38.6 in)
Engine type O.H.C.
Displacement 89.9 cc (5.5 cu-in)
Fuel Used
92# nonleaded gasoline
Front wheel 58 kg (127.6 lbs)
Rear wheel 56.5 kg (124.3 lbs)
Net weight
Total 114.5 kg (251.9 lbs)
Front wheel 61.5 kg (135.3 lbs)
Rear wheel 58.5 kg (128.7 lbs)
Gross
weight
Total 120 kg (264 lbs)
Front wheel 18*7-8
Tires
Rear wheel 18*9-8
Ground clearance 104 mm (4.16 in)
Starting system Motor & Kick starter
Type Gasoline, 4-stroke
Cylinder arrangement Single cylinder
Combustion chamber
type
Semi-sphere
Valve arrangement O.H.C., chain drive
Bore x stroke
47X51.8 mm
(1.85X2.04 in)
Compression ratio 10:1
Compression pressure
1600 kPa (16
kgf/cm², 227.2 psi)
Intake Open 2° (ATDC)
(1mm) Close 26° (ABDC)
Exhaust Open 44° (BBDC)
Port
timin
g
(1mm) Close -17° (BTDC)
Intake 0.1 mm (0.004 in)
Valve
clearance
(cold)
Exhaust 0.1 mm (0.004 in)
Idle speed 1800 rpm
Lubrication type
Forced pressure &
Wet sump
Oil pump type
Inner/outer rotor type
Oil filter type Full-flow filtration
Oil capacity
0.8 L (0.7 lmp qt,
0.85 US qt)
Lubrication System
Oil exchanging
capacity
0.7 L (0.62 lmp qt,
0.74 US qt)
Engine
Cooling Type Air cooling
Air cleaner type Sponge
Fuel capacity
5.5 L (12.1 lmp gal,
1.45 US gal)
Type PTE
Main jet No. #80
Venturi
dia.(mm)
φ16
Fuel System
Carburetor
Throttle type PISTON
Type CDI
Ignition timing 13°BTDC/1800rpm
Contact breaker Non-contact point type
Spark plug NGK CR7HSA
Ignition System
Spark plug gap
0.6～0.7 mm (0.024～
0.028 in)
Electrical Equipment
Battery Capacity 12V4AH
Clutch Type CVT
Type Helical gear
Transm
is-sion
Gear
Operation
Automatic centrifugal
Type
Type V-Belt
Primary
reduction
0.8~2.5
Power Drive System
Reduction
Gear
Final
reduction
9.255
FR/RR tire rolling
circumference
1436 mm (57.44 in)
Front
25 kPa (0.25 kg/cm²,
3.6 psi)
Tire pressure
Rear
25 kPa (0.25 kg/cm²,
3.6 psi)
Left 35°
Moving Device
Turning angle
Right 35°
RearDisk brake
Brake system type
Front Drum brake
Front
Swing axle
Damping
Device
Suspension
type
Rear
Swing arm
Frame type Steel tube frame
Page 6
1. GENERAL INFORMATION
1-3
Mongoose 70/MXER 70R
Model No. LA15
Overall length 1415 mm (56.6 in)
Overall width 880 mm (35.2 in)
Overall height 910 mm (36.4 in)
Wheel base 965 mm (38.6 in)
Engine type O.H.C.
Displacement 69.4 cc (4.25 cu-in)
Fuel Used 92# nonleaded gasoline
Front wheel 53 kg (116.6 lbs)
Rear wheel 52 kg (114.4 lbs)
Net weight
Total 105 (231 lbs)
Front wheel 57 kg (125.4 lbs)
Rear wheel 54 kg (118.8 lbs)
Gross weight
Total 111 kg (244.2 lbs)
Front wheel 16*8-7
Tires
Rear wheel 16*8-7
Ground clearance 85 mm (3.4 in)
Starting system Motor & Kick starter
Type Gasoline, 4-stroke
Cylinder arrangement Single cylinder
Combustion chamber type Semi-sphere
Valve arrangement O.H.C., chain drive
Bore x stroke
47X40 mm
(1.88X1.6 in)
Compression ratio 7.9:1
Compression pressure
1400 kPa (14 kgf/c
m
²,
200 psi)
Open 6° (ATDC)
Intake
(1mm)
Close 28° (ABDC)
Open 38° (BBDC)
Port
timin
g
Exhaust
(1mm)
Close -6° (BTDC)
Intake 0.04 mm (0.0016 in)
Valve
clearance
(cold)
Exhaust 0.04 mm (0.0016 in)
Idle speed 2000rpm
Lubrication
type
Forced pressure &
Wet sump
Oil pump type Inner/outer rotor type
Oil filter type Full-flow filtration
Oil capacity
0.8 L (0.7 lmp qt,
0.85 US qt)
Lubrication System
Oil exchanging
capacity
0.7 L (0.62 lmp qt,
0.74 US qt)
Engine
Cooling Type Air cooling
Air cleaner type Sponge
Fuel capacity
5.5 L (12.1 lmp gal,
1.45 US gal)
Type PTE
Main jet No. #85
Venturi dia.(mm) φ16
Fuel S
y
stem
Carbureto
Throttle type PISTON
Type CDI
Ignition timing 13°BTDC/1800rpm
Contact breaker Non-contact point type
Spark plug NGK CR7HSA
Ignition System
Spark plug gap
0.6～0.7 mm
(0.024～0.028 in)
Electrical E
q
ui
p
ment
Battery Capacity 12V4AH
Clutch Type CVT
Type Helical gear
Transmission Gea
r
Operation
Automatic centrifugal
Type
Type V-Belt
Primary
reduction
0.8~3.1
Power Drive S
y
stem
Reduction
Gear
Final
reduction
27.257
FR/RR tire rolling
circumference
1266 mm (50.64 in)
Front
Tire pressure
Rear
25 kPa (0.25 kg/c
m
²,
3.6 psi)
Left 35°
Moving Device
Turning angle
Right 35°
Rear Disk brake
Brake system type
Front Drum brake
Front Swing axle
Damping Device
Suspension type
Rear Swing arm
Frame type Steel tube frame
Page 7
1. GENERAL INFORMATION
1-4
Mongoose 50-4T /MXER 50R-4T
Model No. LB10
Overall length 1430 mm (58 in)
Overall width 870 mm (34.8 in)
Overall height 900 mm (37.8 in)
Wheel base 965 (38.6 in)
Engine type O.H.C.
Displacement 49.5 cc (3.01 cu-in)
Fuel Used 92# nonleaded gasoline
Front wheel
51 kg (132lbs)
Rear wheel
50 kg (132 lbs)
Net weight
Total
101 kg (264 lbs)
Front wheel
55 kg (138.6 lbs)
Rear wheel
53 kg (134.2 lbs)
Gross weight
Total
108 kg (272.8 lbs)
Front wheel 16*8-7
Tires
Rear wheel 16*8-7
Ground clearance 130 mm (7.6 in)
Starting system Motor & Kick starter
Type Gasoline, 4-stroke
Cylinder arrangement Single cylinder
Combustion chamber type Semi-sphere
Valve arrangement O.H.C., chain drive
Bore x stroke
39X41.4 mm
(1.54X1.63 in)
Compression ratio 10:1
Compression pressure
1400 kPa (14 kgf/c
m
2
,
200 psi)
Open 2° (BTDC)
Intake
(1mm)
Close 26° (ABDC)
Open 44° (BBDC)
Port
timin
g
Exhaust
(1mm)
Close -17° (ATDC)
Intake
Valve
clearance
(cold)
Exhaust
0.04 mm (0.0016 in)
Idle speed (rpm) 2000rpm
Lubrication
type
Forced pressure &
Wet sump
Oil pump type Inner/outer rotor type
Oil filter type Full-flow filtration
Oil capacity
0.8 L (0.7 lmp qt,
0.84US qt)
Lubrication System
Oil exchanging
capacity
0.7 L (0.62 lmp
qt,0.74US qt)
Engine
Cooling Type Air cooling
Air cleaner type Sponge
Fuel capacity
5.5 L (12.1 lmp gal,
1.45 US gal)
Type PTE
Main jet No. #80
Venturi dia.(mm) φ16
Fuel S
y
stem
Carbureto
Throttle type PISTON
Type CDI
Ignition timing 13°BTDC/2000rpm
Contact breaker Non-contact point type
Spark plug NGK CR7HSA
Ignition System
Spark plug gap
0.6～0.7 mm (0.024
～0.028 in)
Electrical E
q
ui
p
ment
Battery Capacity 12V4AH
Clutch Type CVT
Type Helical gear
Transmission Gea
r
Operation
Automatic centrifugal
Type
Type V-Belt
Primary
reduction
0.8~2.5
Power Drive S
y
stem
Reduction
Gear
Final
reduction
27.136
FR/RR tire rolling
circumference
1546/1514 mm
(61.84/60.56 in)
Front
Tire pressure
Rear
25 kPa (0.25 kgf/cm
2
,
3.6 psi)
Left 35°
Moving Device
Turning angle
Right 35°
Rear Disk brake
Brake system type
Front Drum brake
Front Swing axle
Damping Device
Suspension
type
Rear Swing arm
Frame type Steel tube frame
Page 8
1. GENERAL INFORMATION
1-5
Mongoose 50-2T /MXER 50R-2T
Name & Model No. LA10
Overall length 1385 mm (55.4 in)
Overall width 875 mm (35 in)
Overall height 890 mm (35.6 in)
Wheel base 900 mm (36 in)
Engine type 2-stroke.
Displacement 49.4 cc (3.02 cu-in)
Fuel Used 92# nonleaded gasoline
Front wheel 49.6 kg (109.12 lbs)
Net weight Rear wheel 50.7 kg (111.54 lbs)
Total 100.3 kg (220.66 lbs)
Front wheel 54.6 kg (120.12 lbs)
Gross weight Rear wheel 55.7 kg (122.54 lbs)
Total 110.3 kg (242.66 lbs)
Front wheel 16*8-7
Tires
Rear wheel 16*8-7
Ground clearance 72 mm (2.88 in)
Starting system
Motor & Kick starte
r
Type Gasoline, 2-stroke
Cylinder arrangement Single cylinder
Combustion chamber type Semi-sphere
Valve arrangement Reed valve & piston
Bore x stroke
39X41.4 mm
(1.56X1.656 in)
Compression ratio 7.2:1
Compression pressure
1200 kPa (12 kgf/c
m
2
,
170.4 psi)
Intake
Open Automatic controlled
Port
(1mm)
Close Automatic controlled
timin
g
Exhaust
Open ─
(1mm)
Close ─
Valve clearance
Intake ─
(cold)
Exhaust ─
Idle speed 2000 rpm
Lubrication type Separate type
Oil pump type Plunger type
Oil filter type Full-flow filtration
Engine
Cooling Type Air cooling
Air cleaner type & No Sponge
Fuel capacity
5.5 L (12.1 lmp gal, 1.45
US gal)
Type PB
Main jet No. 82
Venturi dia.(mm) φ14
Fuel System
Carburetor
Throttle type PISTON
Type CDI
Ignition timin
g
15°BTDC/1700r
pm
Contact breaker Non-contact point type
Spark plug NGK BR8HAS
Ignition System
Spark plug gap
0.6～0.7 mm
(0.024～0.028 in)
Electrical Equipment
Battery Capacity 12V4AH
Clutch Type CVT
Type Helical gear
Transmission Gear
Operation
Automatic centrifugal
Type
Type V-Belt
Primary
reduction
0.895~3.113
Power Drive System
Reduction
Gear
Final
reduction
11.05
FR/RR tire rolling
circumference
1247 mm (49.88 in)
Fron
t
Tire pressure
Rear
25 kPa (0.25 kgf/cm
2
,
3.6 psi)
Turning Left 35°
Moving Device
angle
Right 35°
Brake system
Rea
r
Drum brake
type Front Drum brake
Front
Swing axle
Damping
Suspension
type
Rear
Swing arm
Frame type Steel tube frame
Page 9
1. GENERAL INFORMATION
1-6
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.
Use genuine parts and lubricants.
When servicing the motorcycle, be sure
to use special tools for removal and
installation.
After disassembly, clean removed parts.
Lubricate sliding surfaces with engine oil
before reassembly.
Page 10
1. GENERAL INFORMATION
1-7
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.
When using a spanner or other tools,
make sure not to damage the motorcycle
surface.
After operation, check all connecting
points, fasteners, and lines for proper
connection and installation.
When connecting the battery, the positive
(+) terminal must be connected first.
After connection, apply grease to the
battery terminals.
Terminal caps shall be installed securely.
Page 11
1. GENERAL INFORMATION
1-8
If the fuse is burned out, find the cause
and repair it. Replace it with a new one
according to the specified capacity.
After operation, terminal caps shall be
installed securely.
When taking out the connector, the lock
on the connector shall be released before
operation.
Hold the connector body when
connecting or disconnecting it.
Do not pull the connector wire.
Check if any connector terminal is
bending, protruding or loose.
Confir
m
Capacity
Page 12
1. GENERAL INFORMATION
1-9
The connector shall be inserted
completely.
If the double connector has a lock,
lock it at the correct position.
Check if there is any loose wire.
Before connecting a terminal, check
for damaged terminal cover or loose
negative terminal.
Check the double connector cover for
proper coverage and installation.
Insert the terminal completely.
Check the terminal cover for proper
coverage.
Do not make the terminal cover opening
face up.
Secure wire harnesses to the frame with
their respective wire bands at the
designated locations.
Tighten the bands so that only the
insulated surfaces contact the wire
harnesses.
Snapping!
Page 13
1. GENERAL INFORMATION
1-10
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.
When fixing the wire harnesses, do not
make it contact the parts which will
generate high heat.
Route wire harnesses to avoid sharp
edges or corners. Avoid the projected
ends of bolts and screws.
Route wire harnesses passing through the
side of bolts and screws. Avoid the
projected ends of bolts and screws.
N
o Contact !
Page 14
1. GENERAL INFORMATION
1-11
Route harnesses so they are neither
pulled tight nor have excessive slack.
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.
Do not break the sheath of wire.
If a wire or harness is with a broken
sheath, repair by wrapping it with
protective tape or replace it.
When installing other parts, do not press
or squeeze the wires.
Do not pull
too tight!
Do not press or
squeeze the wire.
Page 15
1. GENERAL INFORMATION
1-12
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.
When a testing device is used, make sure
to understand the operating methods
thoroughly and operate according to the
operating instructions.
Be careful not to drop any parts.
When rust is found on a terminal, remove
the rust with sand paper or equivalent
before connecting.
Do you understand
the instrument? Is
the instrument set
correctly?
Remove Rust !
Page 16
1. GENERAL INFORMATION
1-13
Symbols:
The following symbols represent the
servicing methods and cautions included
in this service manual.
: Apply engine oil to the
specified points. (Use
designated engine oil for
lubrication.)
: Apply grease for
lubrication.
: Transmission Gear Oil
(90#)
: Use special tool.
: Caution
: Warning
Engine Oil
Grease
Gear Oil
Special
Page 17
1. GENERAL INFORMATION
1-14
TORQUE VALUES
STANDARD TORQUE VALUES
Item
Torque
N•m (kgf•m, lbf•ft)
Item
Torque
N•m (kgf•m, lbf•ft)
5mm bolt and nut
6mm bolt and nut
8mm bolt and nut
10mm bolt and nut
12mm bolt and nut
14mm bolt and nut
5(0.5, 4)
10 (1, 7)
22 (2.2, 16)
35 (3.5, 25)
55 (5.5, 40)
70 (7, 50)
4mm screw
5mm screw
6mm screw, SH bolt
6mm flange bolt and nut
8mm flange bolt and nut
10mm flange bolt and nut
3 (0.3, 2)
4 (0.4, 3)
9 (0.9, 6.5)
12 (1.2, 9)
27 (2.7, 20)
40 (4, 29)
Torque specifications listed below are for important fasteners.
ENGINE (90cc/70cc/50cc-4T)
Item Q‘ty
Thread dia.
(mm)
Torque
N•m (kgf•m, lbf•ft)
Remarks
Stud bolt
Oil filter screen cap
L cover
Cam shaft holder nut (90cc)
Cam shaft holder nut
Tappet ADJ nut
Pivot tensioner bolt
Lifter tensioner bolt
Lifter tensioner cap
Mission case bolt
Mission fill bolt
Driver face nut
Clutch outer nut
Drive plate nut
Oneway clutch nut (90&70 cc)
ACG flywheel nut
Spark plug
Drain plug
Oil pump screw
Head CYL stud bolt (IN pipe)
Head CYL stud bolt (EX pipe)
A.C.G Startor
Fan
4
1
8
4
4
2
1
2
1
7
1
1
1
1
1
1
1
1
1
2
2
3
4
8
30
6
8
7
5
6
6
6
8
8
12
10
28
24
10
10
10
3
6
8
5
6
9 (0.9, 6.5)
15 (1.5, 11)
12 (1.2, 9)
20 (2, 14)
14 (1.4, 10)
9 (0.9, 6.5)
10 (1, 7)
12 (1.2, 9)
4.5 (0.45, 3)
27 (2.7, 19)
18 (1.8, 13)
60 (6, 43)
40 (4, 29)
55 (5.5, 40)
55 (5.5, 40)
40 (4, 29)
12 (1.2, 9)
25 (2.5, 18)
2 (0.2 1.4)
9 (0.9, 6.5)
9 (0.9, 6.5)
10 (1, 7)
8 (0.8, 5.8)
Apply oil
Apply oil
Apply oil
Apply oil
Page 18
1. GENERAL INFORMATION
1-15
ENGINE (50cc-2T)
Item Q‘ty
Thread dia.
(mm)
Torque
N•m (kgf•m,
lbf•ft)
Remarks
Cylinder head bolt
Clutch drive plate nut
Drive face nut
Clutch outer nut
ACG flywheel nut
Mission fill bolt
Drive plate nut
Spark plug
4
1
1
1
1
1
1
1
6
28
10
10
10
8
28
14
10 (1, 7)
55 (5.5, 40)
40 (4, 29)
40 (4, 29)
40 (4, 29)
15 (1.5, 11)
55 (5.5, 40)
15 (1.5, 11)
FRAME
Item Q‘ty
Thread dia.
(mm)
Torque
N•m (kgf•m,
lbf•ft)
Remarks
Steering stem nut
Front Swing arm nut
Front wheel nut
Rear wheel nut
Front wheel hub nut
Rear wheel hub nut
Front shock absorber upper mount bolt
Front shock absorber lower mount bolt
Rear shock absorber upper mount bolt
Rear shock absorber lower mount bolt
Rear swing arm axle hub bolt
Rear axle hub bolt
Front engine mounting bolt
Rear engine mounting bolt
Rear caliper bolt
Brake oil bolt
M/C holder
Exhaust muffler lock bolt
Exhaust muffler lock nut (90&70 cc)
Exhaust muffler lock nut (50 cc)
Rod-end nut
1
4
8
8
2
2
2
2
1
1
1
4
2
2
2
2
2
4
2
2
4
14
10
10
10
12
14
10
10
10
10
14
12
10
8
8
10
6
8
8
6
8
70 (7, 50)
45 (4.5, 32)
45 (4.5, 32)
45 (4.5, 32)
60 (6, 43)
80 (8, 58)
40 (4, 29)
40 (4, 29)
40 (4, 29)
40 (4, 29)
70 (7, 50)
70 (7, 50)
45 (4.5, 32)
32 (3.2, 23)
32 (3.2, 23)
35 (3.5, 25)
12 (1.2, 9)
35 (3.5, 25)
22 (2.2, 16)
10 (1, 7)
35 (3.5, 25)
Page 19
1. GENERAL INFORMATION
1-16
SPECIAL TOOLS
90cc/70cc/50cc-4T
Tool Name Tool No.
Remarks Ref. Page
Clutch spring compressor A120E00034
Bearing puller A120E00037
Valve spring compressor A120E00040
Oil seal & bearing installer A120E00014
Tappet adjuster A120E00012
Long socket wrench A120E00015
Start clutch puller A120E00006
Flywheel puller A120E00001
Universal holder A120E00017
50cc-2T
Tool Name Tool No. Remarks Ref. Page
Flywheel puller A120E00001
Oil seal and bearing install A120E00014
Universal holder A120E00017
Clutch spring compressor A120E00034
Bearing puller A120E00037
Crankshaft install A120E00016
Crankshaft & crankcase install A120E00024
Crankcase puller A120E00026
Crankshaft Bearing puller A120E00030
Page 20
1. GENERAL INFORMATION
1-17
LUBRICATION POINTS
ENGINE (90cc/70/50-4T)
Lubrication Points Lubricant
Valve guide/valve stem movable part
Cam lobes
Valve rocker arm friction surface
Cam chain
Cylinder lock bolt and nut
Piston surroundings and piston ring grooves
Piston pin surroundings
Cylinder inside wall
Connecting rod/piston pin hole
Connecting rod big end
Crankshaft right side oil seal
Crankshaft one-way clutch movable part
Oil pump drive chain
Balance gear
A.C. generator
Starter one-way clutch
Bearing movable part
O-ring face
Oil seal lip
•Genuine KYMCO Engine Oil (SAE15W-40)
•API SG Engine Oil
Transmission gear and movable parts Gear oil: SAE90#
ENGINE (50cc-2T)
NO. Lubrication Points Lubricant
1 Crankcase sliding & movable KYMCO 2-STROKE OIL or QUIVALENT
2 Cylinder movable parts KYMCO 2-STROKE OIL or QUIVALENT
3 Transmission gear (final gear) SAE-90#
4 Kick starter spindle bushing Grease
5 Drive pulley movable parts Grease
6 Starter pinion movable parts Grease
Page 21
1. GENERAL INFORMATION
1-18
FRAME
The following is the lubrication points for the frame.
Use general purpose grease for parts not listed.
Apply clean engine oil or grease to cables and movable parts not specified. This will avoid
abnormal noise and rise the durability of the ATV.
Throttle Cable
Steering Column Lowe
r
Front Swing Arm Bush
Front Swing Ar
m
Steering knuckle
Steering knuckle
Page 22
1. GENERAL INFORMATION
1-19
Rear Axle Hub
Collar/Oil
Seal/Bearing
Driven Sprocket
Rear Swing Arm Axle
Page 23
1. GENERAL INFORMATION
1-20
CABLE & HARNESS ROUTING
Headlight Wire Couple
r
Rear Brake Cable/Fluid Hose
Handlebar Switch Couple
r
Ignition Switch Couple
r
Harness Wire
Ignition Coil
Kill Switch (Safety)
Front Brake Cable
Front Stop Switch Wire
Throttle Cable
REG.REC Wire
Pilot Leads
(50cc-2T)
Rear Stop Switch Wire
Handlebar Switch Wire
Rear Stop Switch Wire
Kill Switch (Safety)
Front Stop Switch Wire
Front Brake Cable
Rear Brake Cable/Fluid Hose
REG.REC
Page 24
1. GENERAL INFORMATION
1-21
Oil Outlet Tube
(50cc-2T)
Oil Level Switch Wire
(50cc-2T)
A.C.G. Wire
Ignition Coil
Ignition Coil Wire
Starter Motor Wire
Page 25
1. GENERAL INFORMATION
1-22
Taillight Couple
r
Battery Positive (+)
Battery Negative (-)
Oil Pump Control Cable
(50cc-2T)
Ignition Coil Wire
Rear Brake Cable/Fluid Hose
Air Inlet Hose
Throttle Cable
Fuel Tube
Autobystarter Wire
Harness Wire
Resisto
r
Page 26
1. GENERAL INFORMATION
1-23
WIRING DIAGRAMS
Mongoose 90/MXER 90R/Mongoose 50-4T OFF ROAD
G
Page 27
1. GENERAL INFORMATION
1-24
MXER 90R ON ROAD
Page 28
1. GENERAL INFORMATION
1-25
Mongoose 70
Page 29
1. GENERAL INFORMATION
1-26
Mongoose 50-2T/MXER 50R-2T OFF ROAD
Page 30
1. GENERAL INFORMATION
1-27
MXER 50R-2T ON ROAD
Page 31
1. GENERAL INFORMATION
1-28
TROUBLESHOOTING
ENGINE WILL NOT START OR IS HARD TO START
Empty fuel tank
Clogged fuel line between fuel
tank and carburetor
Clogged float oil passage
Clogged fuel tank cap breather
hole
Clogged fuel filter
Clogged fuel valve passage
Faulty spark plug
Fouled spark plug
Faulty ignition unit
Faulty pulser coil
Broken or shorted ignition coil
Broken or shorted exciter coil
Faulty ignition switch
Weak or dead battery
Faulty starter clutch
Valve clearance too small
Valve stuck open
Worn cylinder, piston and piston
rings
Leaking cylinder head gasket
Air leaking through intake pipe
Leaking intake manifold
Incorrect ignition timing
Incorrectly adjusted air screw
Flooded carburetor
Clogged air cleaner
Throttle valve excessively open
Check if fuel reaches
carburetor by loosening
drain screw
Remove spark plug and
install it into spark plug
cap to test spark by
connecting it to engine
ground
Inspection/Adjustment
Probable Cause
Spark jumps
Normal
compression
Engine does no
t
fire
Weak or no spark
Low or no
compression
Engine fires bu
t
does not start
Test cylinde
r
compression
Start engine by following normal starting
p
rocedure
Remove spark plug and
inspect again
Symptom
Fuel reaches
carburetor
Fuel does no
t
reach carburetor
Wet spark plug
Dry spark plug
Page 32
1. GENERAL INFORMATION
1-29
ENGINE LACKS POWER
Clogged air cleaner
Restricted fuel flow
Clogged fuel tank cap breather hole
Clogged exhaust muffler
Carburetor fuel level too low
Faulty ignition unit
Faulty pulser coil
Improper valve clearance
adjustment
Excessively worn valve seat
(protruded valve stem)
Improper valve and seat contact
Worn cylinder and piston rings
Leaking cylinder head gasket
Improper valve timing
Clean and unclog
Fouled spark plug
Incorrect heat range plug
Oil level too high
Oil level too low
Oil not changed
Clogged oil line
Faulty oil pump
Worn cylinder and piston rings
Mixture too lean
Poor quality fuel
Excessive carbon build-up in
combustion chamber
Ignition timing too early
Excessive carbon build-up in
combustion chamber
Poor quality fuel
Clutch slipping
Mixture too lean
Ignition timing too early
Start engine and
accelerate lightly for
observation
Inspection/Adjustment
Symptom
Probable Cause
Engine speed
Correct timin
g
Engine speed does no
t
increase sufficientl
y
Incorrect timin
g
Check ignition timing
(using a timing light)
Test cylinder compression
Check carburetor fo
r
clogging
Rapidly accelerate or run
at high speed
Remove spark plug and
inspect
Check if engine overheats
Check valve clearance
Correc
t
Incorrec
t
N
ormal
com
p
ression
Abnormal
compression
Remove oil dipstick and
check oil level and condition
Remove cylinder head oil
pip
e bolt and inspec
t
Engine overheats
Engine does no
t
overheats
Plug not fouled o
r
discolored
Plug fouled o
r
discolored
Correct and no
t
contaminated
Incorrect o
r
contaminated
Valve train lubricated
prop
erl
y
Valve train no
t
lubricated properl
y
Engine does not knock
Engine knocks
Not clogged
Clogged
Page 33
1. GENERAL INFORMATION
1-30
POOR PERFORMANCE (ESPECIALLY AT IDLE AND LOW SPEEDS)
Faulty ignition unit
Faulty pulser coil
Mixture too rich (turn screw
out)
Mixture too lean (turn screw in)
Deteriorated O-ring
Carburetor not securely
tightened
Damaged insulator rubber
Faulty or fouled spark plug
Faulty CDI unit
Faulty A.C. generator
Faulty ignition coil
Broken or shorted spark plug
wire
Faulty ignition switch
Remove spark plug and
install it into spark plug
cap to test spark by
connecting it to engine
g
round
Inspection/Adjustment Symptom Probable Cause
Check ignition timing
Check carburetor gaske
t
for air leaks
Check carburetor ai
r
screw adjustment
Correct timing
Incorrect timing
Correctly adjusted
No air leak
Air leaks
Good spark
Weak or inter-
mittent spark
Incorrectly adjusted
Page 34
1. GENERAL INFORMATION
1-31
POOR PERFORMANCE (AT HIGH SPEED)
Faulty CDI unit
Faulty pulser coil
Improperly adjusted valve
clearance
Worn valve seat
Empty fuel tank
Clogged fuel tube or filter
Clogged Fuel tank cap breather
hole
Clean and unclog
Cam timing gear aligning marks
not aligned
Faulty spring
Inspection/Adjustment Symptom Probable Cause
Check ignition timing
Check carburetor jets
for clogging
Check fuel pump fo
r
fuel supply
Correct timing
Incorrect timing
Check valve spring
tension
Check valve clearance
Fuel flows freely
Fuel flow restricted
Correc
t
Incorrec
t
Not clogged
Clogged
Correctly adjusted
Incorrectly adjusted
Not weakened
Weak spring
Check valve timing
Page 35
1. GENERAL INFORMATION
1-32
POOR CHARGING (BATTERY OVER DISCHARGING OR OVERCHARGING)
Undercharging
Dead battery
Faulty battery
Faulty A.C. generator coil
Broken yellow wire
Shorted white and yellow
wires
Broken red wire
Faulty regulator/rectifier
Poorly connected coupler
Faulty A.C. generator
Overcharging
Broken green wire
Poorly connected coupler
Faulty regulator/rectifier
Start engine and tes
t
limit voltage of battery
terminals
Connect battery (+) wire
to regulator/rectifier
coupler red wire and
battery (-) wire to engine
ground and test voltage
Inspection/Adjustment
Inspection/Adjustment
Symptom
Symptom
Probable Cause
Probable Cause
Normal voltage
B
attery has voltage
with ignition
switch “ON”
Normal
Voltage does no
t
B
attery has no
voltage with ignition
switc
h
“ON”
Resistance too high
Normal voltage No voltage
Measure resistance
between AC generator
coil terminals
Normal
Abnormal
Check regulator/rectifier
coupler for loose
connection
Normal
Abnormal
Connect battery (+) wire
to regulator/rectifier
coupler green wire and
battery (-) wire to engine
ground and test voltage
Check regulator/rectifier
coupler for loose
connection
Page 36
1. GENERAL INFORMATION
1-33
NO SPARK AT SPARK PLUG
Faulty spark plug
Loose spark plug cap
Poorly connected coupler
Faulty ignition switch
Weak battery
Faulty pulser coil
Faulty ignition coil
Faulty charging system
Broken wire harness
Poorly connected coupler
Faulty CDI unit
Faulty ignition coil
Replace with a new
spark plug and inspect
a
g
ain
Check CDI unit coupler
for looseness
Inspection/Adjustment Symptom
Probable Cause
Normal
Abnormal
Normal
Abnormal
Normal
Abnormal
Abnormal
Measure resistance
between terminals of
CDI unit cou
pler
Check related parts
Check ignition coil with
a CDI unit tester
Weak or no spark
Not loose
Good spark
Loose
Good
Good
Check spark plug cap
and high-tension wire
for looseness
Check CDI unit with a
CDI unit tester
Page 37
2. FRAME COVERS/EXHAUST MUFFLER
2-0
2
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
FRAME COVERS/EXHAUST MUFFLER
__________________________________________________________________________________
SERVICE INFORMATION------------------------------------------------ 2- 2
FRAME COVERS----------------------------------------------------------- 2- 3
EXHAUST MUFFLER REMOVAL-------------------------------------- 2- 7
TAILLIGHT BULB --------------------------------------------------------- 2- 8
2
Page 38
2. FRAME COVERS/EXHAUST MUFFLER
2-1
Page 39
2. FRAME COVERS/EXHAUST MUFFLER
2-2
SERVICE INFORMATION
GENERAL INSTRUCTIONS
• When removing frame covers, use special care not to pull them by force because the cover joint
claws may be damaged.
• Make sure to route cables and harnesses according to the Cable & Harness Routing.
TORQUE VALUES
Exhaust muffler lock bolt 35 N-m (3.5 kgf-m, 25 lbf-ft)
Exhaust muffler lock nut (90cc/70cc/50cc-2T) 20 N-m (2 kgf-m, 15 lbf-ft)
Exhaust muffler lock nut (50cc-4T) 10 N-m (1 kgf-m, 7 lbf-ft)
TROUBLESHOOTING
Noisy exhaust muffler
• Damaged exhaust muffler
• Exhaust muffler joint air leaks
Lack of power
• Caved exhaust muffler
• Exhaust muffler air leaks
• Clogged exhaust muffler
Page 40
2. FRAME COVERS/EXHAUST MUFFLER
2-3
FRAME COVERS
HANDLEBAR COVER REMOVAL
Remove the two screws attaching the
handlebar cover.
Disconnect the oil level indicator leads.
Remove the handlebar cover.
INSTALLATION
Reverse the “HANDLEBAR COVER
REMOVAL” procedures.
SEAT REMOVAL
To remove the seat, pull upward the seat
lock lever and pull up the seat at the rear.
To install the seat, align the tabs on the seat
with the grommets on the frame and press
the seat down until it locks.
HANDLEBAR REMOVAL
Remove handlebar cover. (See page 2-3)
Remove the rear brake master cylinder
attaching bolts (disk brake).
Disconnect the rear brake cable (drum
brake).
Disconnect the handlebar switch coupler
and lead (under front fender).
Bolts
Handlebar Cove
r
Seat Lock Leve
r
Sea
t
Make sure that the seat is securely fitted.
＊
Bolts
Handlebar Switch Coupler and Lead
Page 41
2. FRAME COVERS/EXHAUST MUFFLER
2-4
Disconnect the front brake cables.
Disconnect the remote stop switch and front
brake stop switch leads.
Remove the two screws and speed limiter
cover.
Disconnect the throttle cable.
Remove the two bolts and handlebar cover
holder.
Remove the four bolts and upper handlebar
holders.
Remove the handlebar.
INSTALLATION
Reverse the “HANDLEBAR REMOVAL”
procedures (refer to the “STEERING
SYSTEM” section in the chapter 12).
Refer to the “BRAKE LEVER FREE
PLAY” section in the chapter 3 to adjust
brake lever free play.
＊
Front Brake Cables
Remote Engine Stop
Switch Leads
Front Brake Stop
Switch Leads
Screws
Throttle Cable
Bolts
Bolts
Page 42
2. FRAME COVERS/EXHAUST MUFFLER
2-5
FRONT FENDER REMOVAL
Remove the seat. (See page 2-3)
Remove the handlebar. (See page 2-3)
Remove the six screws and nuts attaching
the front fender and right/left foot boards.
Remove the four screws and two nuts
attaching the front fender and rear fender at
the right/left side.
Remove the two bolts attaching front fender
at the right/left side.
Remover the fuel filler cap.
Remove the front fender and disconnect the
ignition switch coupler.
During removal, do not pull the joint
claws forcedly to avoid damage.
＊
After remove, be sure to tighten the fuel
filler cap.
＊
Screws
Screws
Screws
Screws
Bolts
Fuel Filler Cap
Ignition Switch Couple
r
Page 43
2. FRAME COVERS/EXHAUST MUFFLER
2-6
INSTALLATION
Reverse the “FRONT FENDER
REMOVAL” procedures.
REAR FENDER REMOVAL
Remove the front fender. (See page 2-5)
Remove the battery. (See chapter 14)
Remove the starter relay and CDI unit.
Remove the ten screws attaching the rear
fender and foot boards at the right/left side.
Remove the two screws attaching the rear
fender at the rear.
Remove the three bolts attaching the rear
fender at the center and then remove the
rear fender.
After remove, be sure to tighten the fuel
filler cap.
＊
Starter Relay Ignition Uni
t
Screws
Screws
Screws
Bolts
Page 44
2. FRAME COVERS/EXHAUST MUFFLER
2-7
FOOT BOARD REMOVAL
Remove front fender. (See page 2-5)
Remover rear fender. (See page 2-6)
Remove the four bolts attaching the
right/left foot board.
FRONT CARRIER REMOVAL
Remove the four bolts attaching front
carrier at the right/left side.
EXHAUST MUFFLER
REMOVAL
Remove the two nuts attaching the exhaust
pipe and cylinder head.
Remove the three bolts attaching the
exhaust muffler, then remove the exhaust
muffler.
Bolts
Bolts
N
uts
Bolts
Page 45
2. FRAME COVERS/EXHAUST MUFFLER
2-8
Inspect the gasket.
If the exhaust gas leaks, the gasket should
be replaced.
Install by reversing the removal sequence.
Torque:
Exhaust muffler lock bolt
35 N-m (3.5 kgf-m, 25 lbf-ft)
Exhaust muffler lock nut (90cc/70cc/50cc-
2T)
20 N-m (2 kgf-m, 15 lbf-ft)
Exhaust muffler lock nut (50cc-4T)
10 N-m (1 kgf-m, 7 lbf-ft)
TAILLIGHT BULB
REMOVAL
Remove the two screws and taillight lens.
Turn bulb and remove it.
Be sure to install a new exhaust gasket.
＊
Gaske
t
Screws
Bulb
Page 46
3. INSPECTION/ADJUSTMENT
3-0
3
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
INSPECTION/ADJUSTMENT
__________________________________________________________________________________
SERVICE INFORMATION------------------------------------------------ 3- 1
MAINTENANCE SCHEDULE-------------------------------------------- 3- 3
FUEL LINE/THROTTLE OPERATION--------------------------------- 3- 4
AIR CLEANER -------------------------------------------------------------- 3- 5
SPARK PLUG/CYLINDER COMPRESSION-------------------------- 3- 7
VALVE CLEARANCE (90cc/70cc/50cc-4T) --------------------------- 3- 8
CARBURETOR IDLE SPEED -------------------------------------------- 3- 8
ENGINE OIL (90cc/70cc/50cc-4T) --------------------------------------- 3- 9
TRANSMISSION OIL------------------------------------------------------ 3-11
DRIVE BELT/BRAKE SHOES/BRAKE PADS/BRAKE FLUID --- 3-12
BRAKE LEVER FREE PLAY (DRUM BRAKE) ---------------------- 3-13
STEERING SYSTEM INSPECTION------------------------------------- 3-14
TOE-IN ADJUSTMENT --------------------------------------------------- 3-15
WHEELS/TIRES ------------------------------------------------------------ 3-16
DRIVE CHAIN SLACK ADJUSTMENT-------------------------------- 3-17
CABLE INSPECTION AND LUBRICATION-------------------------- 3-19
SUSPENSION LUBRICATION------------------------------------------- 3-19
HEADLIGHT BEAM ADJUSTMENT (ON ROAD ONLY)---------- 3-20
BRAKE PEDAL ADJUSTMENT (ON ROAD ONLY)---------------- 3-20
BRAKE FULID -------------------------------------------------------------- 3-21
3
Page 47
3. INSPECTION/ADJUSTMENT
3-1
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.
•Gasoline is extremely flammable and is explosive under some conditions. The working area
must be well-ventilated and do not smoke or allow flames or sparks near the working area or
fuel storage area.
SPECIFICATIONS
ENGINE
Throttle grip free play : 1～4 mm (0.04～0.16 in)
Spark plug gap : 0.6～0.7 mm (0.024～0.028 in)
Spark plug: Standard : 90 cc: NGK: CR7HSA
: 70 cc: NGK: CR7HAS
: 50 cc-4T: NGK: CR7HAS
: 50 cc-2T: NGK: R8HAS
Valve clearance : 90 cc: IN: 0.1mm (0.004 in)
EX: 0.1mm (0.004 in)
: 70 cc IN: 0.04mm (0.0016 in)
EX: 0.04mm (0.0016 in)
: 50 cc-4T IN: 0.04mm (0.0016 in)
EX: 0.04mm (0.0016 in)
Idle speed : 90 cc 1800±100rpm
: 70 cc 2000±100rpm
: 50 cc-2T 2000±100rpm
: 50 cc-4T 2000±100rpm
Engine oil capacity (90cc/70cc/50cc-4T):
At disassembly : 0.8 L (0.7 lmp qt , 0.85 US qt)
At change : 0.7 L (0.62 lmp qt , 0.74 US qt)
Gear oil capacity :
At disassembly : 0.12 L (0.11 lmp qt , 0.13 US qt)
At change : 0.11 L (0.1 lmp qt , 0.12 US qt)
Cylinder compression : 90 cc 16kg/cm²(1600kpa, 227.2psi)
: 70 cc 14kg/cm²(1400kpa, 198.8psi)
: 50 cc-4T 14kg/cm²(1400kpa, 198.8psi)
: 50 cc-2T 12kg/cm²(1200kpa, 170.4psi)
Page 48
3. INSPECTION/ADJUSTMENT
3-2
Ignition timing : 90 cc BTDC 13°/1800rpm
: 70 cc BTDC 13°/1800rpm
: 50 cc-4T BTDC 13°/2000rpm
: 50 cc-2T BTDC 15°/1700rpm
CHASSIS
Front brake free play: 10～20 mm (0.4～0.8 in)
Drive chain slack: 10～20 mm (0.4～0.8 in)
TIRE PRESSURE
1 Rider
Front 25 kPa (0.25 kgf/cm², 3.6 psi)
Rear 25 kPa (0.25 kgf/cm², 3.6 psi)
TIRE SIZE: 90 cc:
Front: 18*7-8
Rear: 18*9-8
: 70cc/50cc-4T/50cc-2T:
Front: 16*8-7
Rear: 16*8-7
TORQUE VALUES
Front wheel nut 45 N-m (4.5 kgf-m, 32 lbf-ft)
Rear wheel nut 45 N-m (4.5 kgf-m, 32 lbf-ft)
Page 49
3. INSPECTION/ADJUSTMENT
3-3
MAINTENANCE SCHEDULE
This chapter includes all information necessary to perform recommended inspections and
adjustments. These preventive maintenance procedures, if followed, will ensure more reliable
vehicle operation and a longer service life. The need for costly overhaul work will be greatly
reduced. This information applies to vehicles already in service ad well as new vehicles that are
being prepared for sale. All service technicians should be familiar with this entire chapter.
Initial Every
Item Remarks
1
month3month6month6month
1
year
Valves (except 50cc-2T)
Check valve clearance. Adjust if
necessary.
○○○○
Spark plug
Check condition. Clean or
replace if necessary.
○○○○○
Air clearance Clean. Replace if necessary. ○○○○
Carburetor
Check idle speed/starter
operation. Adjust if necessary.
○○○○
Fuel line
Check fuel hose for cracks or
damage. Replace if necessary.
○○○
Engine oil (except 50cc2T)
Replace (Warm engine before
draining).
○○○○
Engine oil filter
screen(except 50cc-2T)
Clean. Replace if necessary.
○○
Transmission oil
Check oil leakage. Replace
every 12 months.
○○
Brake system
Check operation. Adjust if
necessary.
○○○○○
Drive belt
Check operation/replace if
damage or excessive wear.
○○
Wheels
Check balance/damage/runout.
Replace if necessary.
○○○○
Wheel bearings
Check bearings assembly for
looseness/damage. Replace if
damaged.
○○○○
Steering system
Check operation/replace if
damage. Check toe-in/adjust if
necessary.
○○○○○
Knuckle shafts Lubricate every 6 months. ○○○
Fitting/Fasteners
Check all chassis fittings and
fasteners. Correct if necessary.
○○○○○
Spark arresterl
Clean
○○○
• In the interest of safety, we recommend these items should be serviced only by an authorized
KYMCO motorcycle dealer.
Page 50
3. INSPECTION/ADJUSTMENT
3-4
FUEL LINE
Check the fuel tubes and replace any parts,
which show signs of deterioration, damage
or leakage.
THROTTLE OPERATION
Check the throttle to swing for smooth
movement.
Measure the throttle to swing free play.
Free Play: 1～4 mm (0.04～0.16 in)
To adjust throttle free play:
1. Slide the rubber sleeves back to expose
the throttle cable adjuster.
2. Loosen the lock nut, then turn the
adjuster to obtain the correct free play.
(1~4 mm or 0.04~0.16 in)
3. Tighten the lock nut and reinstall the
sleeve.
OIL PUMP ADJUSTMENT (50cc-4T
only)
Open the throttle valve fully and check that
the index mark on the pump body aligns
with the aligning mark on the oil pump
control lever.
Reference tip alignment within 1mm of
index mark on open side is acceptable.
Start and idle the engine, then slowly open
the throttle to increase engine rpm and
check the operation of the oil pump control
lever.
If adjustment is necessary, adjust the oil
pump control cable by loosening the control
cable lock nut and turning the adjusting nut.
After adjustment, tighten the lock nut.
Fuel Filte
r
Fuel Tubes
Rubber Sleeves
Lock Nu
t
Cable Adjuste
r
Throttle Leve
r
Adjust oil pump control cable after the
throttle grip free play is adjusted.
＊
Control Lever Aligning Mark
Lock NutAdjusting Nu
t
Do not smoke or allow flames or sparks
in your working area.
＊
Page 51
3. INSPECTION/ADJUSTMENT
3-5
If the oil pump is not synchronized properly,
the following will occur:
• Excessive white smoke or hard starting
due to pump control lever excessively
open
• Seized piston due to pump control lever
insufficiently open
AIR CLEANER
AIR CLEANER
REPLACEMENT/CLEANING
(90cc/70cc/50cc-4T)
To replace the air cleaner
1. Remove the seat. (See page 2-3.)
2. Remove the five screws and then remove
air filter case cover.
3. Remove the air filter element, and
separate it from the box.
Screws
Air Filter Case Cove
r
Air Filter Elemen
t
Reference tip alignment within 1mm of
index mark on open side is acceptable.
However, the aligning mark on the
control lever must never be on the
closed side of the index mark, otherwise
engine damage will occur because of
insufficient lubrication.
＊
Page 52
3. INSPECTION/ADJUSTMENT
3-6
To replace the air cleaner (50cc-2T)
1. Remove the five screws and air filter case
cover.
2. Remove the air filter element, and
separate it from the box.
To clean the air filter element:
1. Wash the element gently but thoroughly
in solvent.
2. Squeeze the excess solvent out of the
filter and let it dry.
3. Inspect the element. If damaged, replace
it.
4. Apply quality foam air filter oil to the
element. If foam air filter oil is not
available, motor oil may be used.
5. Reinstall the element to the air filter case.
6. Reinstall the element assembly and parts
removed for access.
Apply the engine oil.
Squeeze out the excess oil.
CHANGE INTERVAL
More frequent replacement is required when
riding in unusually dusty or rainy areas.
Use parts cleaning solvent only. Neve
r
use gasoline or low flash point solvents
which may lead to a fire or explosion.
＊
Do not twist or wring out the foa
m
element. This could damage the foam
material.
＊
The element should be wet but not
dripping.
＊
Air Filter Elemen
t
Screws
Air Filter Case Cove
r
Page 53
3. INSPECTION/ADJUSTMENT
3-7
Gap, Wear, and Fouling Deposits
SPARK PLUG
Remove the ignition coil cap and spark
plug.
Check the spark plug for wear and fouling
deposits.
Clean any fouling deposits with a spark
plug cleaner or a wire brush.
Specified Spark Plug:
90cc/70cc/50cc-4T: NGK: CR7HSA
50cc-2T: NGK: BR8HAS
Measure the spark plug gap.
Spark Plug Gap:
0.6～0.7 mm (0.024～0.028 in)
CYLINDER COMPRESSION
Warm up the engine before compression
test.
Remove the spark plug.
Insert a compression gauge.
Open the throttle valve fully and push the
starter button to test the compression.
Compression:
90 cc: 16 kgf/cm²(1600 kPa, 227.2 psi)
70 cc: 14 kgf/cm²(1400kPa, 198.8 psi)
50 cc-4T: 14 kgf/cm²(1400kPa, 198.8 psi)
50 cc-2T: 12 kgf/cm²(1200kPa, 170.4 psi)
If the compression is low, check for the
following:
- Leaky valves
- Valve clearance too small
- Leaking cylinder head gasket
- Worn piston rings
- Worn piston/cylinder
If the compression is high, it indicates that
carbon deposits have accumulated on the
combustion chamber and the piston head.
Cracks, Damage
Washer Deformation
Ignition Coil Cap/Spark Plug
When installing, first screw in the spar
k
plug by hand and then tighten it with a
spark plug wrench.
＊
Compression Gauge
Page 54
3. INSPECTION/ADJUSTMENT
3-8
VALVE CLEARANCE
(90cc/70cc/50cc-4T)
Disconnect the oil recycle tube at the
cylinder head cover.
Remove the four bolts and cylinder head
cover.
Remove the two screws and two bolts, then
remove the fan cover.
Turn the cooling fan clockwise so that the
“T” mark on the flywheel aligns with the
index mark on the crankcase to bring the
round hole on the camshaft gear facing up
to the top dead center on the compression
stroke.
Inspect and adjust the valve clearance.
Valve Clearance:
90cc: IN: 0.1mm (0.004 in)
EX: 0.1mm (0.004 in)
70cc/50cc-4T: IN: 0.04mm (0.0016 in)
EX: 0.04mm (0.0016 in)
Loosen the lock nut and adjust by turning
the adjusting nut
Special tool:
Tappet adjuster A120E00012
CARBURETOR IDLE SPEED
Warm up the engine before this operation.
Start the engine and connect a tachometer.
Turn the throttle stop screw to obtain the
specified idle speed.
Idle Speed:
90 cc: 1800±100rpm
70 cc/50 cc-4T/50 cc-2T: 2000±100rpm
When the engine misses or run erratic,
adjust the air screw.
Inspect and adjust valve clearance while
the engine is cold (below 35°C).
＊
• Check the valve clearance again afte
r
the lock nut is tightened.
＊
Cylinder Head Cove
r
Bolts
Cooling Fan Cove
r
Screws
Bolts
Round Hole
Punch Marks
Tappet Adjuste
r
Throttle Stop Screw
Air Screw
• The engine must be warm for accurate
idle speed inspection and adjustment.
＊
Page 55
3. INSPECTION/ADJUSTMENT
3-9
ENGINE OIL (90cc/70cc/50cc-4T)
OIL LEVEL
Remove the two bolts and right side cover.
Place the machine on a level place.
Warm up the engine for several minutes and
stop it.
Remove the dipstick and wipe it off with a
clean rag. Insert the dipstick in the filler
hole without screwing it in.
Remove the dipstick and inspect the oil
level.
The oil level should be between the
maximum and minimum marks. If the level
is low, add oil to raise it to the proper level.
ENGINE OIL REPLACEMENT
Place the machine on a level place.
Warm up the engine for several minutes and
stop it.
Place a container under the engine.
Remove right side cover.
Remove the oil filler cap and drain plug to
drain the oil.
Reinstall the drain plug and tighten the
drain plug to specification.
Torque: 25 N-m (2.5 kgf-m, 18 lbf-ft)
Fill the engine with oil and install the oil
filler cap.
Warm up the engine for several minutes at
idle speed. Check for oil leakage while
warming up.
Oil Capacity:
At disassembly:
0.8 L (0.7 lmp qt , 0.85 US qt)
At change:
0.7 L (0.62 lmp qt , 0.74 US qt)
Maximum Level Mark
Dipstick/Oil Filler Cap
Minimum Level Mark
Dipstick/Oil Filler Cap
Drain Plug
Be sure no foreign material enters the
crankcase.
＊
Run the engine for 2～3 minutes and
check the oil level after the engine is
stopped for 2～3 minutes.
＊
Right Side Cove
r
Bolts
Page 56
3. INSPECTION/ADJUSTMENT
3-10
ENGINE OIL REPLACEMENT AND
OIL FILTER CLEANING
A. Place the machine on a level place.
B. Warm up the engine for several minutes
and stop it.
C. Place a container under the engine.
D. Remove the oil filler cap and oil filter
cap to drain the oil.
E. Clean the oil strainer with solvent.
F. Inspect the O-ring and replace if
damaged.
G. Reinstall the O-ring, oil strainer,
compression spring and drain plug.
Tighten the drain plug to specification.
Torque: 15 N-m (1.5 kgf-m, 11 lbf-ft)
Oil Capacity:
At disassembly:
0.8 L (0.7 lmp qt , 0.85 US qt)
At change:
0.7 L (0.62 lmp qt , 0.74 US qt)
Oil Filter Cap
．Be sure no foreign material enters the
crankcase.
．When removing the drain plug, the
compression spring, oil strainer and
O-ring will fall out. Take care not to
lose these parts.
＊
Before reinstalling the drain plug, be sure
to install the O-ring, compression spring
and oil strainer.
＊
Oil Filter Cap
Compression Spring
Oil Straine
r
O-ring
Page 57
3. INSPECTION/ADJUSTMENT
3-11
TRANSMISSION OIL
TRANSMISSION OIL
MEASUREMENT
Place the machine on a level place.
Remove the oil filler bolt and check the oil
level. It should be up to the brim of the hole.
If the level is low, add oil to raise it to the
proper level.
Reinstall the oil filler bolt and tighten to
specification.
Torque: 18 N-m (1.8 kgf-m, 13 lbf-ft)
TRANSMISSION OIL REPLACEMENT
Place the machine on a level place.
Place a container under the engine.
Remove the oil filler bolt and drain plug to
drain the oil.
Reinstall the drain plug and tighten to
specification.
Torque: 18 N-m (1.8 kgf-m, 13 lbf-ft)
Fill the engine with oil and install the oil
filler bolt.
Torque: 18 N-m (1.8 kgf-m, 13 lbf-ft)
Oil Capacity:
At disassembly:
0.12 L (0.11 lmp qt , 0.13 US qt)
At change:
0.11 L (0.1 lmp qt , 0.12 US qt)
Start the engine and warm up for a few
minutes. While warming up, check for oil
leakage. If oil leakage is found, stop the
engine immediately and check for the cause.
Oil Filter Bolt/Measurement Hole
Drain Plug
Be sure no foreign material enters the
crankcase.
＊
Page 58
3. INSPECTION/ADJUSTMENT
3-12
DRIVE BELT
Remove the left crankcase cover.
Inspect the drive belt for cracks, scaling,
chipping or excessive wear.
Measure the V-belt width
Service limit:
90cc: 16.5 mm (0.66 in)
70cc: 16.5 mm (0.66 in)
50cc-4T: 17 mm (0.68 in)
50cc-2T: 17.5 mm (0.7 in)
Replace the drive belt if out of specification.
BRAK SHOES
The checking of brake shoes wear will
disassemble the brake. If the lining
thickness below to the wear limit (A) 2 mm
(0.08 in), to replace the shoes as a set.
BRAKE PADS
A wear indicator is provided on each brake.
The indicators allows checking of brake
pads wear. Check the position of the
indicator. If the indicator reaches the wear
limit line, to replace the pads.
BRAKE FLUID
Check if the fluid level is below the lower
level mark through the inspection window.
Drive Bel
t
Inspection Window
Page 59
3. INSPECTION/ADJUSTMENT
3-13
BRAKE LEVER FREE PLAY
(DRUM BRAKE)
The brake lever free play (A) should be
adjusted to 10~20 mm (0.4~0.8 in) at the tip
of the brake lever.
FRONT BRAKE FREE PLAY
ADJUSTMENT
Loosen the upper lock nut and fully turn in
the adjusting bolt.
Loosen the lower lock nut.
Turn the lower adjusting bolt until specified
free play is obtained.
Tighten the lower lock nut.
While applying the front brake, turn out the
upper adjusting bolt until the upper and
lower cable lengths (A) are equal. The cable
joint will become vertical.
Tighten the upper lock nut.
REAR BRAKE FREE PLAY
ADJUSTMENT
Turn the adjusting nut on the brake hub in
direction A to decrease play, and in
direction B to increase play.
Lock Nuts
Adjusting Bolts
Page 60
3. INSPECTION/ADJUSTMENT
3-14
STEERING SYSTEM
INSPECTION
Place the machine on a level place.
Check the steering column bushings and
bearings:
Move the handlebar up and down, and/or
back and forth.
Replace the steering column bushings and
or bearings if excessive play
Check the tie-rod ends
Turn the handlebar to the left and/or right
until it stops completely, then slightly move
the handlebar from left to right.
Replace the tie-rod ends if tie-rod end has
any vertical play.
Raise the front end of the machine so that
there is no weight on the front wheels.
Check ball joints and/or wheel bearings.
Move the wheels lately back and froth.
Replace the front arms and/or wheel
bearings if excessive free play.
Tie-rod Ends
Make sure the cut-out on the adjusting
nut Is seated on the brake arm pin after
making final free play adjustment.
＊
Arm Pin
Adjusting Nu
t
Page 61
3. INSPECTION/ADJUSTMENT
3-15
TOE-IN ADJUSTMENT
Place the machine on a level place.
Measure the toe-in
Adjust if out of specification.
Toe-in measurement steps:
Mark both front tire tread centers.
Raise the front end of the machine so that
there is no weight on the front tires.
Fix the handlebar straight ahead.
Measure the width A between the marks.
Rotate the front tires 180 degrees until the
marks come exactly opposite.
Measure the width B between the marks.
Calculate the toe-in using the formula given
below.
Toe-in = B－A
Toe-in: 0～15mm
If the toe-in is incorrect, adjust the toe-in
Adjust the toe-in step:
Mark both tie-rods ends.
This reference point will be needed during
adjustment.
Loosen the lock nuts (tie-rod end) of both
tie-rods
The same number of turns should be given
to both tie-rods right and left until the
specified toe-in is obtained, so that the
lengths of the rods will be kept the same.
Torque: 30 N-m (3 kgf-m, 22 lbf-ft)
• Be sure that both tie-rod are turned the
same amount. If not, the machine will
drift tight or left even though the
handlebar is positioned straight which
may lead to mishandling and accident.
• After setting the toe-in to specification,
run the machine slowly for some
distance with hands placed lightly on
the handlebar and check that the
handlebar responds correctly. If not,
turn either the right or left tie-rod
within the toe-in specification.
＊
A
B
Tie-rod
Tie-rod End Nuts
Tie-rod
Tie-rod End Nuts
Page 62
3. INSPECTION/ADJUSTMENT
3-16
WHEELS/TIRES
Check the tires for cuts, imbedded nails or
other damages.
Check the tire pressure.
TIRE PRESSURE
1 Rider
Front 25kPa(0.22kgf/cm²,3.6psi)
Rear 25kPa(0.22kgf/cm²,3.6psi)
90 cc:
Front: 18*7-8
Rear: 18*9-8
70cc/50cc:
Front: 16*8-7
Rear: 16*8-7
Check the front wheel hub nut for
looseness.
Check the rear wheel hub nut for looseness.
If the axle nuts are loose, tighten them to the
specified torque.
Torque:
Front: 60 N-m(6 kgf-m, 43 lbf-ft)
Rear : 70 N-m(7 kgf-m, 50 lbf-ft)
WHEEL INSPECTION
Inspect the tire surfaces.
Replace if wear or damage.
Tire wear limit: 3 mm (0.12 in)
Front Axle Nu
t
Tire pressure should be checked when
tires are cold.
＊
RearAxle Nu
t
It is dangerous to ride with a worn out
tire. When a tire wear is out of
specification, replace the tire
immediately.
＊
Page 63
3. INSPECTION/ADJUSTMENT
3-17
Inspect the wheel.
Replace if damage or bends
Always balance the wheel when a tire or
wheel has been changed or replaced.
DRIVE CHAIN SLACK
ADJUSTMENT
Before checking and/or adjusting, rotate the
rear wheels several revolutions and check
slack at several points to find the tightest
point. Check and/or adjust the chain slack
with the rear wheels in this “tightest”
position.
Place the machine on a level place.
Check drive chain slack (A).
Adjust if out of specification.
Drive chain slack:
Approximately 10~20 mm (0.4~0.8 in)
Adjust drive chain slack:
Elevate the rear wheels by placing a suitable
stand under the rear of frame.
Loosen the upper and lower axle holding
bolts.
Bolts
• Never attempt even small repairs to the
wheel.
• Ride conservatively after installing a
tire to allow it to seat itself properly on
the rim.
＊
Too little of chain slack will overload the
engine and other vital parts; keep the
＊
Wheels should be on the ground without
＊
Support the machine securely so there is
＊
Hub Stopper Nu
t
Page 64
3. INSPECTION/ADJUSTMENT
3-18
Turn the adjusting nut, to decrease or
increase chain slack.
Retighten the upper and lower axle holding
bolts.
Torque: 70 N-m (7 kgf-m, 50 lbf-fi)
Drive chain cleaning and lubrication
The drive chain is equipped with rubber O-
rings between the chain plates. Steam
cleaning, high-pressure washes, and certain
solvents can damage these O-rings. Use
only kerosene to clean the drive chain. Wipe
it dry, and thoroughly lubricate it with SAE
30~50 motor oil. Do not use any other
lubricants on the drive chain. They may
contain solvents that could damage the Orings.
Adjusting Nu
t
O-ring
Page 65
3. INSPECTION/ADJUSTMENT
3-19
CABLE INSPECTION AND
LUBRICATION
Inspect the cable sheath.
Replace if damage.
Check the cable operation.
Lubricate or replace if unsmooth operation.
LEVER LUBRICATION
Lubricate the pivoting parts of each lever.
SUSPENSION LUBRICATION
Inject grease into the nipples using a grease
gun until slight over flow is observed from
the thrust covers.
Front Swing
Arm Nipple
Damaged cable sheath may cause
corrosion and interfere with the cable
movement. An unsafe condition may
result so replace such cable as soon as
possible.
＊
Wipe off the excess grease.
＊
Hold cable end high and apply several
drops of lubricant to cable.
＊
Rear Swing
Arm Nipple
Page 66
3. INSPECTION/ADJUSTMENT
3-20
HEADLIGHT BEAM
ADJUSTMENT (ON ROAD
ONLY)
Vertical adjustment:
Turn the ignition switch ON and start the
engine.
Turn on the headlight switch.
Adjust the headlight aim by turning the
headlight aim adjusting screw.
BRAKE PEDAL ADJUSTMENT
( ON ROAD ONLY)
The brake pedal free play should be
adjusted to 5~10 mm (0.2~0.4 in) at the
brake pedal pivot. If the free play is
incorrect, adjust as follows:
Adjust:
1. Keep front brake lever free play at 10~20
mm (0.4~0.8 in).
2. Loosen the locknuts. (R/L front lower
brake cables)
3. Turn the adjusting bolts until the front
lower brake cables is tensed.
4. Apply the front brake lever and check
front brake cam lever to make sure that
the brake does not drag after adjusting.
5. While remove the cable joint case cover
and applying the brake pedal, make sure
the left and right front lower cable
lengths (A and B) are equal. The cable
joint will become vertical.
6. Tighten the locknuts. (R/L front lower
brake cables)
Headligh
t
Adjusting screw
Adjusting Bolts
Locknuts Brake Cam Leve
r
R/L Front Lower Cable
Cable Joint Case Cove
r
Bolts
Cable Join
t
Page 67
3. INSPECTION/ADJUSTMENT
3-21
7. Loosen the locknut. (Brake pedal cable)
8. Turn the adjusting bolt until the specified
free play is obtained.
9. Tighten the locknut. (Brake pedal cable)
BRAKE FLUID
Check if the fluid level is below the lower
level mark through the inspection window.
Locknu
t
Adjusting Blo
t
Brake Pedal Cable
Page 68
4. LUBRICATION SYSTEM
4-0
4
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
LUBRICATION SYSTEM
__________________________________________________________________________________
SERVICE INFORMATION (90cc/70cc/50cc-4T)---------------------- 4- 3
SERVICE INFORMATION (50cc-2T)----------------------------------- 4- 4
ENGINE OIL/OIL FILTER (90cc/70cc/50cc-4T)----------------------- 4- 5
OIL PUMP (90cc) ----------------------------------------------------------- 4- 5
OIL PUMP (70cc/50cc-4T)------------------------------------------------- 4- 9
OIL PUMP BLEEDING (50cc-2T)---------------------------------------- 4-15
OIL TANK (50cc-2T)------------------------------------------------------- 4-16
OIL PUMP (50cc-2T) ------------------------------------------------------- 4-17
OIL FILTER CLEANING (50cc-2T) ------------------------------------- 4-18
4
Page 69
4. LUBRICATION SYSTEM
4-1
LUBRICATION SYSTEM (90cc/70cc/50cc-4T)
Oil Pump
Oil Filter Screen
Crankshaft
Rocker Arm Shaft
Page 70
4. LUBRICATION SYSTEM
4-2
LUBRICATION SYSTEM (50cc-2T)
Page 71
4. LUBRICATION SYSTEM
4-3
SERVICE INFORMATION (90cc/70cc/50cc-4T)
GENERAL INSTRUCTIONS
• The maintenance of lubrication system can be performed with the engine installed in the frame.
• Use care when removing and installing the oil pump not to allow dust and foreign matters to
enter the engine and oil line.
• Do not attempt to disassemble the oil pump. The oil pump must be replaced as a set when it
reaches its service limit.
• After the oil pump is installed, check each part for oil leaks.
SPECIFICATIONS mm (in)
Item Standard Service Limit
Inner rotor-to-outer rotor clearance 0.15 (0.006) 0.2 (0.008)
Outer rotor-to-pump body clearance 0.15～0.2 (0.006～0.008) 0.25 (0.01)
Oil
pump
Rotor end-to-pump body clearance 0.04～0.09 (0.0016～0.0036) 0.12 (0.0048)
TROUBLESHOOTING
Oil level too low Poor lubrication pressure
• Natural oil consumption • Oil level too low
• Oil leaks • Clogged oil filter or oil passages
• Worn or poorly installed piston rings • Not use the specified oil
• Worn valve guide or seal
Page 72
4. LUBRICATION SYSTEM
4-4
SERVICE INFORMATION (50cc-2T)
GENERAL INSTRUCTIONS
• Use care when removing and installing the oil pump not to allow dust and dirt to enter the engine
and oil line.
• Do not attempt to disassemble the oil pump.
• Bleed air from the oil pump if there is air between the oil pump and oil line.
• If the oil is disconnected, refill the oil line with motor oil before connecting it.
SPECIFICATIONS
• Recommended Motor Oil: SAE20W20# 2-stroke Motor Oil
• Oil Capacity : 1 liter (0.88 lmp qt, 1.06 US qt)
Light comes on : 0.25 liter (0.22 lmp qt, 0.265 US qt)
TROUBLESHOOTING
Excessive white smoke or carbon deposits on spark plug
• Oil pump not properly synchronized (excessive oil)
• Poor quality oil
Engine overheating
• Oil pump not properly adjusted (insufficient oiling)
• Poor quality oil
Seized piston
• No oil in tank or clogged oil line
• Oil pump not properly adjusted (insufficient oiling)
• Air in oil line
• Faulty oil pump
Oil not flowing out of tank to engine
• Clogged oil tank cap breather hole
• Clogged oil filter
Page 73
4. LUBRICATION SYSTEM
4-5
Bolts
Right Crankcase Cove
r
Nut
Bolts
Oil Separator Cove
r
ENGINE OIL/OIL FILTER
(90cc/70cc/50cc-4T)
OIL LEVEL AND OIL CHANGE
Refer to the “ENGINE OIL” section in the
chapter 3 to check the oil level and
replacement and oil filter cleaning.
OIL PUMP (90cc)
REMOVAL
Place a container under the engine.
Remove the drain plug to drain the oil. (Ö3-
9)
Remove the A.C. generator flywheel. (Ö14-
8)
Remove the A.C. generator stator and pulsar
coil. (Ö14-8)
Remove the eight right crankcase cover
bolts and the right crankcase cover.
Remove the two bolts and oil separator
cover.
Remove the oil pump driven gear nut.
Remove the oil pump driven gear and drive
chain.
Oil Pump Driven Gea
r
Drive Chain
Page 74
4. LUBRICATION SYSTEM
4-6
Oil Pump
Bolts
Outer Roto
r
Oil Pump Body
Screws
Remove the two oil pump mounting bolts
and the oil pump.
DISASSEMBLY
Remove the screw and disassemble the oil
pump.
INSPECTION
Measure the pump body-to-outer rotor
clearance.
Service Limit: 0.25 mm (0.01 in)
Oil Pump Body
Page 75
4. LUBRICATION SYSTEM
4-7
Outer Roto
r
Inner Roto
r
Inner Roto
r
Pump Cove
r
Outer Roto
r
Measure the inner rotor-to-outer rotor
clearance.
Service Limit: 0.2 mm (0.008 in)
Measure the rotor end-to-pump body
clearance.
Service Limit: 0.12 mm (0.0048 in)
ASSEMBLY
Install the outer rotor, inner rotor and pump
shaft into the pump body.
Install the dowel pin.
Install the pump cover by aligning the hole
in the cover with the dowel pin.
Insert the pump shaft by aligning the flat
on the shaft with the flat in the inner
rotor.
＊
Page 76
4. LUBRICATION SYSTEM
4-8
Screws
Oil Pump
Arrow Mark
Pump Shaf
t
Tighten the screw to secure the pump cover.
Make sure that the pump shaft rotates freely
without binding.
INSTALLATION
Reverse the “OIL PUMP REMOVAL”
procedures.
Make sure that the pump shaft rotates freely
without binding.
Install the oil pump with the arrow on
the pump body facing up and fill the oil
pump with engine oil before installation.
＊
Page 77
4. LUBRICATION SYSTEM
4-9
Bolts
Nut
Bolts
OIL PUMP (70cc/50cc-4T)
REMOVAL
Place a container under the engine.
Remove the drain plug to drain the oil (
page
3-9
).
Remove the A.C. generator flywheel (page
14-8).
Remove the A.C. generator stator and pulsar
coil (page 14-8).
Remove the eight right crankcase cover
bolts and the right crankcase cover.
Remove the oil pump gear nut and oil pump
gear.
Oil Pump Gea
r
Nut
Bolts
Right Crankcase Cove
r
Page 78
4. LUBRICATION SYSTEM
4-10
Remove three oil pump mounting bolts and
the oil pump.
Remove O-rings and dowel pin.
Bolts
Oil Pump
O-rings
Dowel Pin
Page 79
4. LUBRICATION SYSTEM
4-11
Bolts
Screws
Oute
r
Roto
r
Pump Body
Oute
r
Roto
r
Inner Roto
r
DISASSEMBLY
Remove the screws and disassemble the oil
pump.
INSPECTION
Measure the pump body-to-outer rotor
clearance.
Service Limit: 0.25 mm (0.01 in)
Measure the inner rotor-to-outer rotor
clearance.
Service Limit: 0.2 mm (0.008 in)
Page 80
4. LUBRICATION SYSTEM
4-12
Inner Roto
r
Screws
Dowel Pin
Measure the rotor end-to-pump body
clearance.
Service Limit: 0.12 mm (0.0048 in)
ASSEMBLY
Install the outer rotor, inner rotor and pump
shaft into the pump body.
Install the dowel pin.
Install the pump cover by aligning the hole
in the cover with the dowel pin.
Tighten the screw to secure the pump cover.
Make sure that the pump shaft rotates freely
without binding.
Insert the pump shaft by aligning the flat
on the shaft with the flat in the inner
rotor.
＊
Page 81
4. LUBRICATION SYSTEM
4-13
INSTALLATION
Install the O-rings and dowel pin.
Install the oil pump and tighten the bolts.
Make sure that the pump shaft rotates freely
without binding.
Install the oil pump gear and tighten the nut.
Inspect the O-rings and replace if
damaged.
＊
Bolts
Oil Pump
O-rings
Dowel Pin
Oil Pump Gea
r
Nut
Page 82
4. LUBRICATION SYSTEM
4-14
Install the right crankcase cover and tighten
the bolts.
Bolts
Right Crankcase Cove
r
Page 83
4. LUBRICATION SYSTEM
4-15
OIL PUMP BLEEDING (50cc-2T)
OIL INLET LINE/OIL PUMP BLEEDING
Fill the oil tank with recommended oil.
Place a shop towel around the oil pump.
Disconnect the oil inlet tube from the oil
pump and clip it.
Fill the oil pump with oil by squirting clean
oil through the joint. (About 3cc)
Fill the oil line with oil and connect it to the
oil pump.
OIL OUTLET LINE BLEEDING
1. Disconnect the oil outlet tube and bend it
into U shape. Force air out of the tube by
filling it with oil.
2. Start the engine and allow it to idle with
the oil control lever in the fully open
position. Visually check the oil flow.
3. If there is no oil flowing out within 1
minute, bleed air from the oil inlet tube
and oil pump.
• Air in the oil tubes will block oil flow
and result in severe engine damage.
• Bleed air from the oil tubes and oil
pump whenever the oil tubes or pump
have been removed or there is air in
the oil tubes.
＊
Bleed air from the oil inlet tube first,
then bleed air from the oil outlet line.
＊
• Never run the engine in a closed area.
• Do not increase the engine speed at
will.
＊
Oil Outlet Line
Oil Pump
Oil Outlet Line
Page 84
4. LUBRICATION SYSTEM
4-16
OIL TANK (50cc-2T)
OIL TANK REMOVAL
Remove the oil level switch connector.
Remove the two bolts attaching the oil tank.
Disconnect the oil inlet tube.
Drain the oil inside the oil tank into a clean
container.
Remove the oil tank.
The installation sequence is the reverse of
removal.
• Connect the oil tube properly.
• Bleed air from the oil pump after
installation. (See page 4-15)
• The oil tube clip (at the oil tank side)
must be locked from inside of the oil
tube joint.
＊
Oil Level Switch Connecto
r
Bolts
Oil Inlet Tube
Page 85
4. LUBRICATION SYSTEM
4-17
OIL PUMP (50cc-2T)
REMOVAL
Disconnect the oil outlet tube from the oil
pump.
Disconnect the oil pump control cable from
the pump body.
Disconnect the oil inlet tube.
Remove the oil pump control cable plate
bolts.
Remove the oil pump from the crankcase.
OIL PUMP INSPECTION
Remove the oil pump and inspect the
following items:
• Weakened O-ring
• Damage to crankcase mating surface
• Damage to pump body
• Control lever operation
• Oil leaks through oil seals
• Worn or damaged pump pinion
Do not allow foreign matters to enter the
crankcase. Before removing the oil
pump, clean the oil pump and crankcase
surfaces.
＊
Do not disassemble the oil pump which
cannot be used after disassembly.
＊
O-ring
Gea
r
Control Leve
r
Oil Inlet Tube
Oil Pump Control Cable
Oil Pump Control Cable
Oil Outlet Tube
Before disconnecting the oil line, clip
the oil line to avoid oil flowing out and
then plug the oil line after it is
disconnected.
＊
Bolts
Oil Pump
Oil Pump Control
Cable Plate
Page 86
4. LUBRICATION SYSTEM
4-18
OIL PUMP INSTALLATION
Install the oil pump into the crankcase.
Install the oil pump control cable plate.
Connect the oil inlet line and oil outlet tube
properly.
Connect the oil pump control cable.
Bleed air from the oil pump. (See page 4-
15)
OIL FILTER CLEANING (50cc2T)
Disconnect the oil tube at the oil pump side
and allow oil to drain into a clean container.
Remove the tube clip at the oil tank side and
disconnect the oil tube.
Remove the oil filter.
Clean the oil filter screen with compressed
air.
Install the oil filter in the reverse order of
removal and fill the oil tank with specified
oil up to the proper level.
Bleed air from the oil pump and oil lines.
• Lubricate the O-ring with grease or
engine oil before installation.
• Make sure that the oil pump is inserted
into the crankcase.
• Apply molybdenum disulfide or
grease to the pump pinion.
＊
Grease or Engine Oil
• Connect the oil tube properly.
• Bleed air from the oil pump after
installation.
• The oil tube clip (at the oil tank side)
must be locked from inside of the oil
tube joint.
＊
Filter Screen
Oil Filte
r
Clip
• Connect the oil tubes securely.
• Install the tube clip at the oil tank side
and also install the clip to the lower oil
tube that goes to the oil pump.
• Check for oil leaks.
＊
Page 87
5. FUEL SYSTEM
5-0
5
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
FUEL SYSTEM
__________________________________________________________________________________
SERVICE INFORMATION------------------------------------------------ 5- 2
FUEL TANK ----------------------------------------------------------------- 5- 4
FUEL VALVE REMOVAL------------------------------------------------ 5- 4
THROTTLE VALVE---------------------------------------------------------- 5- 7
AIR CLEANER (90cc/70cc/50cc-4T) ------------------------------------ 5- 9
AIR CLEANER (50cc-2T) ------------------------------------------------- 5-10
CARBURETOR-------------------------------------------------------------- 5-11
REED VAVLE (50cc-2T) -------------------------------------------------- 5-16
5
Page 88
5. FUEL SYSTEM
5-1
Page 89
5. FUEL SYSTEM
5-2
SERVICE INFORMATION
GENERAL INSTRUCTIONS
• Do not bend or twist control cables. Damaged control cables will not operate smoothly.
• When disassembling fuel system parts, note the locations of O-rings. Replace them with new
ones during reassembly.
• Before float chamber disassembly, loosen the drain screw to drain the residual gasoline into a
clean container.
• After the carburetor is removed, plug the intake manifold side with a clean shop towel to prevent
foreign matters from entering.
• When cleaning the carburetor air and fuel jets, the O-rings and diaphragm must be removed first
to avoid damage. Then, clean with compressed air.
• When the machine is not used for over one month, drain the residual gasoline from the float
chamber to avoid erratic idling and clogged slow jet due to deteriorated fuel.
SPECIFICATIONS
Standard
Item
90cc 70cc 50cc-4T 50cc-2T
Type PTE PB
Venturi dia. φ16 φ14
Slow jet No. #40 #38
Main jet No. #80 #85 #80
Adjust method Piston
Idle speed 1800±100 rpm 2000±100rpm
Throttle grip free play 1～4 mm (0.04～0.16 in)
Float level 10.2 mm (0.408 in) 8 mm (0.32 in)
Air screw opening 2 2 2 1±1/4
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 90
5. FUEL SYSTEM
5-3
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
• No spark at plug
• Clogged air cleaner Lean mixture
• Intake air leak • Clogged carburetor fuel jets
• Improper throttle operation • Float level too low
• Intake air leak
Engine idles roughly, stalls or runs poorly • Clogged fuel tank cap breather hole
• Faulty auto bystarter • Bent, kinked or restricted fuel line
• Ignition malfunction
• Faulty carburetor Rich mixture
• Poor quality fuel • Float level too high
• Lean or rich mixture • Clogged air jets
• Incorrect idle speed • Clogged air cleaner
Misfiring during acceleration
• Faulty ignition system
• Faulty carburetor
Backfiring at deceleration
• Float level too low
• Incorrectly adjusted carburetor
• Faulty exhaust muffler
Page 91
5. FUEL SYSTEM
5-4
FUEL TANK
REMOVAL
Remove front fender (See page 2-5).
Switch the fuel valve “OFF”.
Disconnect the fuel outlet tube from fuel
valve.
Remove two screws attaching the fuel valve
and holder.
Remove the two bolts and then remove the
fuel tank.
INSTALLATION
Reverse the “FUEL TANK REMOVAL”
procedures.
FUEL VALVE
REMOVAL
Remove the screw and then remove control
switch.
Disconnect all fuel tubes and then remove
fuel valve.
Warnin
g
Fuel Tank
Screw
Fuel Valve
Bolts
Fuel Outlet Tube
• Keep sparks and flames away from the
work area.
• Wipe off any spilled gasoline.
Control Switch
Fuel Tubes
Screws
• Keep sparks and flames away from the
work area.
• Drain gasoline into a clean container.
＊
Page 92
5. FUEL SYSTEM
5-5
DISASSEMBLY
Remove the two screws on the retaining ring
and then remove retaining ring.
Remove the washer and control shaft.
Remove the rubber gasket from the fuel
valve body.
INSPECTION
Inspect the fuel valve body for dirt and clog.
Clean if necessary.
Replace the rubber gasket with new ones if
they are damaged or deteriorated.
Replace the O-rings with new ones if they
are damaged or deteriorated.
ASSEMBLY
Reverse the “DISASSEMBLY” procedures.
Install rubber gasket, control shaft, washer
and retaining ring.
Fuel Valve Body
Control Shaf
t
Rubber Gaske
t
Retaining Ring
Washe
r
Screws
Control Shaf
t
O-ring
• Aligning the tab on the control shaft
with the outlet duct in the fuel valve
body.
• Aligning the tab on the retaining ring
with the outlet duct in the fuel valve
body.
＊
Tab
Outlet Duc
t
Outlet Duc
t
Tab
Page 93
5. FUEL SYSTEM
5-6
INSTALLATION
Reverse the “FUEL VALVE REMOVEAL”
procedures.
Connect all fuel tube.
Reserve Fuel Tube
Main Fuel Tube
Outlet Fuel Tube
Page 94
5. FUEL SYSTEM
5-7
THROTTLE VALVE
DISASSEMBLY
Remove the fuel tank. (Refer to “FUEL
TANK” section in the chapter 5)
Remove the carburetor cap.
Pull out the throttle valve.
Compress the spring to disconnect the
throttle cable by hand.
Remove the spring from the throttle valve
Carburetor Cap
Spring
Throttle Valve
Throttle Cable
Page 95
5. FUEL SYSTEM
5-8
Pry off the needle retainer and remove the jet
needle.
Check the throttle valve and jet needle for
wear or damage.
ASSEMBLY
Reverse the “DISASSEMBLY” procedures.
Install the throttle valve into the carburetor
body.
Throttle Valve
N
eedle Retaine
r
Jet Needle
Align the groove in the throttle valve
with the throttle stop screw on the
carburetor body.
＊
Throttle Stop Screw
Groove
Page 96
5. FUEL SYSTEM
5-9
AIR CLEANER (90cc/70cc/50cc-4T)
CLEANING
Refer to “AIR CLEANER” section in the
chapter 3.
REMOVAL
Remove front fender. (See page 2-5)
Disconnect the oil recycle tube from cylinder
head and frame.
Remove the bolt at the air cleaner left side.
Loosen the screw at the band and remove bolt at
the air cleaner right side, then remove air cleaner.
INSTALLATION
Reverse the “REMOVAL” procedures.
Oil Recycle Tube
Bol
t
Bol
t
Screw
Band
Page 97
5. FUEL SYSTEM
5-10
AIR CLEANER (50cc-2T)
CLEANING
Refer to “AIR CLEANER” section in the
chapter 3.
REMOVAL
Remove front fender. (See page 2-5)
Disconnect the air inlet hose from the frame.
Remove the bolt at the air cleaner left side.
Loosen the screw at the band and remove bolt at
the air cleaner right side, then remove air cleaner.
INSTALLATION
Reverse the “REMOVAL” procedures.
Air Inlet Hose
Bol
t
Bol
t
Screw
Page 98
5. FUEL SYSTEM
5-11
CARBURETOR
REMOVAL
Remove the fuel tank, carburetor cap and air
filter. (Refer to chapter 5)
Loosen the drain plug to drain the gasoline
from the float chamber.
Disconnect the fuel tube from carburetor and
auto bystarter leads.
Remove the two bolts (nuts) attaching
carburetor, then remove carburetor and
insulator.
INSTALLATION
Reverse the “REMOVAL” procedures.
Check the carburetor insulator and O-rings
for wear or damage.
Fuel Drain Plug
• Keep sparks and flames away from the
work area.
• Drain gasoline into a clean container.
＊
Bolts
Fuel Tube
Auto Bystarte
r
Insulato
r
When installation, do not allow foreign
particles to enter the carburetor.
＊
When installation, be sure the insulato
r
O-ring face the intake manifold.
＊
Insulato
r
Insulator O-ring
O-ring
Page 99
5. FUEL SYSTEM
5-12
DISASSEMBLY
Remove auto bystarter cap.
Remove the two screws and then remove
auto bystarter and plate.
Remove the three float chamber screws and
remove the float chamber.
Pull out the float pin, then remove float and
float valve.
Remove the main jet, needle jet holder, and
needle jet.
Remove the slow jet.
Remove the air screw and throttle stop
screw.
Auto Bystarter Cap
Screws
Float Valve
Floa
t
Main Jet/Needle Je
t
Holder/Needle Jet
Auto Bystarte
Screws
Float Chambe
r
Float Pin
Throttle Stop Screw
Slow Je
t
Air Screw
Page 100
5. FUEL SYSTEM
5-13
CAUTIONS!
ASSEMBLY
Reverse the “DISASSEMBLY” procedures.
• Be careful not to damage the jets an
d
jet holder when removing them.
• Before removal, turn the throttle stop
screw and air screw in and count the
number of turns until they seat lightly
and then make a note of this.
• Do not force the screw against its seat
to avoid seat damage.
• Be sure to install the O-ring in the
reverse order of removal.
＊
N
eedle Je
t
Throttle Stop Screw
SpringAir Screw
Spring
Washe
r
O-ring
Main Je
t
N
eedle Jet Holde
r
Slow Je
t
• When installing the air screw, return it
to the original position as noted during
removal
• Refer to the “CARBURETOR IDLE
SPEED” section in chapters to perform
the idle speed adjustment.
• After the carburetor is installed, be
sure to perform the Exhaust Emission
＊
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