KYMCO MXU 50 REVERSE, MXU 50, MX'ER 50 Service Manual
By KWANG YANG Motor Co., Ltd.
First Edition, Jan 2006
All rights reserved. Any reproduction or
unauthorized use without the written permission of
KWANG YANG Motor Co., Ltd.
is expressly prohibited.
T100LB10DE
PREFACE
This Service Manual describes the
technical features and servicing
procedures for the KYMCO MXU 50
REVERSE/MXU 50/MX’ER 50.
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 19 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/INSTALLATION 6
CYLINDER HEAD/CYLINDER/PISTON 7
A.C. GENERATOR 8
KICK STARTER/DRIVE
PULLEY/CLUTCH/DRIVEN PULLEY
9
FINAL REDUCTION
(MXU 50/MX’ER 50)
10
FINAL REDUCTION/TRANSMISSION
SYSTEM (MXU 50 REVERSE)
11
CRANKCASE/CRANKSHAFT 12
FRONT WHEEL/FRONT BRAKE/
FRONT SUSPENSION/STEERING
SYSTEM
13
REAR WHEEL /SWING
ARM/HYDRAULIC BRAKE
14
BATTERY/CHARGING SYSTEM/A.C.
GENERATOR
15
IGNITION SYSTEM 16
STARTING SYSTEM 17
LIGHTS/SWITCHES 18
ONLY ATV ON ROAD AVAILABLE 19
The information and contents included in
this manual may be different from the
ATV in case specifications are changed.
KYMCO reserves the right to make
changes at any time without notice and
without incurring any obligation.
ENGINE
CHASSIS
ELECTRICAL
EQUIPMENT
1. GENERAL INFORMATION
1-0
ATV 50
1
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
GENERAL INFORMATION
__________________________________________________________________________________
SERIAL NUMBER---------------------------------------------------------- 1- 1
SPECIFICATIONS---------------------------------------------------------- 1- 2
SERVICE PRECAUTIONS------------------------------------------------ 1- 5
TORQUE VALUES --------------------------------------------------------- 1-13
SPECIAL TOOLS ----------------------------------------------------------- 1-14
LUBRICATION POINTS -------------------------------------------------- 1-14
CABLE & HARNESS ROUTING (MX’ER 50) ------------------------ 1-17
CABLE & HARNESS ROUTING (MXU 50 REVERSE/MXU 50) - 1-21
WIRING DIAGRAM (MX’ER 50 ON ROAD) ------------------------- 1-26
WIRING DIAGRAM (MX’ER 50 OFF ROAD) ------------------------ 1-27
WIRING DIAGRAM (MXU 50 ON ROAD)---------------------------- 1-28
WIRING DIAGRAM (MXU 50 REVERSE ON ROAD)-------------- 1-29
TROUBLESHOOTING----------------------------------------------------- 1-30
1
1. GENERAL INFORMATION
1-1
ATV 50
SERIAL NUMBER
Location of Frame Serial Numbe
r
Location of Engine Serial Numbe
r
1. GENERAL INFORMATION
1-2
ATV 50
SPECIFICATIONS
Model No. LA10
Name MX’ER 50
Overall length 1685 mm (67.4 in)
Overall width 980 mm (39.2 in)
Overall height 1030 mm (41.2 in)
Wheel base 1120 mm (44.8 in)
Engine type Air cooled 2-stroke
Displacement 49.4 cm3 (2.964 cu-in)
Fuel Used
92# nonleaded
gasoline
Front wheel 67 kg (147.4 lbs)
Dry weight Rear wheel 73 kg (160.6 lbs)
Total 140 kg (308 lbs)
Front wheel 73 kg (160.6 lbs)
Curb weight Rear wheel 77 kg (169.4 lbs)
Total 150 kg (330 lbs)
Front wheel 20*7-8
Tires
Rear wheel 22*10-8
Ground clearance 130 mm (5.2 in)
Min. turning radius 2500 mm (100 in)
Starting system
Starting motor &
kick starter
Type Air cooled 2-stroke
Cylinder arrangement Single cylinder
Combustion chamber typeSemi-sphere
Valve arrangement Reed valve & piston
Bore x stroke
39 x 41.4 mm
(1.56 x 1.656 in)
Compression ratio 7.2:1
Compression pressure
12 kgf/c
m
2
(1200 kPa,
170.4 psi)
Open
Port
Intake
Close
Automatic controlled
timin
g
Open
Exhaust
Close
Automatic controlled
Intake －
Valve clearance
Exhaus
t
－
Idle speed (rpm) 1800
Lubrication type Separate type
Oil pump type Plunger type
Oil filter type Full-flow filtration
Air cleaner type Sponge
Fuel capacity 8.1 liters
Type PB
Main jet No. 80
Venturi dia φ14 mm (φ0.56 in)
Throttle type Valve piston
Type CDI
Ignition timing 22°/2000 rpm
Spark plug NGK-BR8HAS
Spark plug gap 0.6～0.7mm
Battery Capacity 12V4AH
Clutch Type CVT
Operation Automatic centrifugal
Type
Type Chain drive
Reduction 1st －
ratio 2nd －
Final gear ratio 23.678
Front Caster angle －
Axle Trail length －
Front 0.35 kgf/cm2 (35 kPa,
4.97 psi)
Tire pressure
Rear 0.35 kgf/cm
2
(35 kPa,
4.97 psi)
Turning Left 44°
angle Right 44°
Brake system Rear Disk brake
type Front Drum brake
Suspension Front Swing
type Rear Swing arm
Shock
Front Swing
type Rear Swing arm
Frame type SP pipe
Engine
Fuel S
y
stem
Carbureto
r
Electrical Equipment
I
g
nition S
y
stem
Power Drive System
Reduction
Gear
Moving Device
Damping
Device
1. GENERAL INFORMATION
1-3
ATV 50
Model No. LB10
Name MXU 50
Overall length 1775 mm (71 in)
Overall width 950 mm (38 in)
Overall height 1040 mm (41.6 in)
Wheel base 1120 mm (44.8 in)
Engine type Air cooled 2-stroke
Displacement 49.4 cm3 (2.964 cu-in)
Fuel Used
92# nonleaded
gasoline
Front wheel 87 kg (191.4 lbs)
Dry weight Rear wheel 89 kg (195.8 lbs)
Total 176 kg (387.2 lbs)
Front wheel 92 kg (202.4 lbs)
Curb weight Rear wheel 94 kg (206.8 lbs)
Total 186 kg (409.2 lbs)
Front wheel 21*7-10
Tires
Rear wheel 22*10-10
Ground clearance 165 mm (6.6 in)
Min. turning radius 2900 mm (116 in)
Starting system
Starting motor &
kick starter
Type Air cooled 2-stroke
Cylinder arrangement Single cylinder
Combustion chamber typeSemi-sphere
Valve arrangement Reed valve & piston
Bore x stroke
39 x 41.4 mm
(1.56 x 1.656 in)
Compression ratio 7.2:1
Compression pressure
12 kgf/c
m
2
(1200 kPa,
170.4 psi)
Open
Port
Intake
Close
Automatic controlled
timin
g
Open
Exhaust
Close
Automatic controlled
Intake －
Valve clearance
Exhaus
t
－
Idle speed (rpm) 1800
Lubrication type Separate type
Oil pump type Plunger type
Oil filter type Full-flow filtration
Air cleaner type Sponge
Fuel capacity 8.1 liters
Type PB
Main jet No. 80
Venturi dia φ14 mm (φ0.56 in)
Throttle type Valve piston
Type CDI
Ignition timing 22°/2000 rpm
Spark plug NGK-BR8HAS
Spark plug gap 0.6～0.7mm
Battery Capacity 12V8AH
Clutch Type CVT
Operation Automatic centrifugal
Type
Type Chain drive
Reduction 1st －
ratio 2nd －
Final gear ratio 23.678
Front Caster angle －
Axle Trail length －
Front 0.28 kgf/cm2 (28 kPa, 4
psi)
Tire pressure
Rear 0.28 kgf/cm
2
(28 kPa, 4
psi)
Turning Left 40°
angle Right 40°
Brake system Rear Disk brake
type Front Drum brake
Suspension Front Swing
type Rear Swing arm
Shock
Front Swing
type Rear Swing arm
Frame type SP pipe
Engine
Fuel S
y
stem
Carbureto
r
Electrical Equipment
I
g
nition S
y
stem
Power Drive System
Reduction
Gear
Moving Device
Damping
Device
1. GENERAL INFORMATION
1-4
ATV 50
Model No. LB10
Name MXU 50 REVERSE
Overall length 1786 mm (71 in)
Overall width 958 mm (38 in)
Overall height 1010 mm (40 in)
Wheel base 1105 mm (44 in)
Engine type Air cooled 2-stroke
Displacement 49.4 cm3 (2.964 cu-in)
Fuel Used
92# nonleaded
gasoline
Front wheel 78 kg (171.6 lbs)
Dry weight Rear wheel 80 kg (176 lbs)
Total 158 kg (347.6 lbs)
Front wheel 83 kg (182.6 lbs)
Curb weight Rear wheel 84 kg (184.8 lbs)
Total 167 kg (36734 lbs)
Front wheel 21*7-10
Tires
Rear wheel 22*10-10
Ground clearance 162 mm (6.6 in)
Min. turning radius 2900 mm (116 in)
Starting system
Starting motor &
kick starter
Type Air cooled 2-stroke
Cylinder arrangement Single cylinder
Combustion chamber typeSemi-sphere
Valve arrangement Reed valve & piston
Bore x stroke
39 x 41.4 mm
(1.56 x 1.656 in)
Compression ratio 7.2:1
Compression pressure
12 kgf/c
m
2
(1200 kPa,
170.4 psi)
Open
Port
Intake
Close
Automatic controlled
timin
g
Open
Exhaust
Close
Automatic controlled
Intake －
Valve clearance
Exhaus
t
－
Idle speed (rpm) 1800
Lubrication type Separate type
Oil pump type Plunger type
Oil filter type Full-flow filtration
Air cleaner type Sponge
Fuel capacity 8.1 liters
Type PB
Main jet No. 80
Venturi dia φ14 mm (φ0.56 in)
Throttle type Valve piston
Type CDI
Ignition timing 13.5°/1500 rpm
Spark plug NGK-BR8HAS
Spark plug gap 0.6～0.7mm
Battery Capacity 12V8AH
Clutch Type CVT
Operation
Automatic centrifugal
Type
Primary reduction
system
Helical gear/spur gear
Secondary reduction
system
Chain drive
Primary reduction ratio 1.2 – 3.5
Secondary reduction
ratio
20.12
Reverse ratio 46.11
Front Caster angle －
Axle Trail length －
Front 0.28 kgf/cm2 (28 kPa, 4
psi)
Tire pressure
Rear 0.28 kgf/cm
2
(28 kPa, 4
psi)
Turning Left 40°
angle Right 40°
Brake system Rear Disk brake
type Front Drum brake
Suspension Front Swing
type Rear Swing arm
Shock
Front Swing
type Rear Swing arm
Frame type SP pipe
Engine
Fuel S
y
stem
Carbureto
r
Electrical Equipment
I
g
nition S
y
stem
Power Drive System
Moving Device
Damping
Device
1. GENERAL INFORMATION
1-5
ATV 50
SERVICE PRECAUTIONS
Make sure to install new gaskets, O-rings,
circlips, cotter pins, etc. when
reassembling.
When tightening bolts or nuts, begin with
larger-diameter to smaller ones at several
times, and tighten to the specified torque
diagonally.
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.
1. GENERAL INFORMATION
1-6
ATV 50
Apply or add designated greases and
lubricants to the specified lubrication
points.
After reassembly, check all parts for proper
tightening and operation.
When two persons work together, pay
attention to the mutual working safety.
Disconnect the battery negative (-) terminal
before operation.
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.
1. GENERAL INFORMATION
1-7
ATV 50
If the fuse is burned out, find the cause and
repair it. Replace it with a new one
according to the specified capacity.
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
1. GENERAL INFORMATION
1-8
ATV 50
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!
1. GENERAL INFORMATION
1-9
ATV 50
After clamping, check each wire to make
sure it is secure.
Do not squeeze wires against the weld or
its clamp.
After clamping, check each harness to
make sure that it is not interfering with any
moving or sliding parts.
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 !
1. GENERAL INFORMATION
1-10
ATV 50
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.
1. GENERAL INFORMATION
1-11
ATV 50
After routing, check that the wire harnesses
are not twisted or kinked.
Wire harnesses routed along with
handlebar should not be pulled tight, have
excessive slack or interfere with adjacent
or surrounding parts in all steering
positions.
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 !
1. GENERAL INFORMATION
1-12
ATV 50
Symbols:
The following symbols represent the
servicing methods and cautions included in
this service manual.
: Apply engine oil to the
specified points. (Use
designated engine oil for
lubrication.)
: Apply grease for lubrication.
: Caution
: Warning
Engine Oil
Grease
Special
＊
＊
1. GENERAL INFORMATION
1-13
ATV 50
TORQUE VALUES
STANDARD TORQUE VALUES
Item
Torque
kgf-m (N-m, lbf-ft)
Item
Torque
kgf-m (N-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
0.5 (5, 3.6)
1 (10, 7.2)
2.2 (22, 16)
3.5 (35, 25)
5.5 (55, 40)
7 (70, 50)
4mm screw
5mm screw
6mm screw, SH bolt
6mm flange bolt and nut
8mm flange bolt and nut
10mm flange bolt and nut
0.3 (3, 2.2)
0.4 (4, 2.9)
0.9 (9, 6.5)
1.2 (12, 9)
2.7 (27, 20)
4 (40, 29)
Torque specifications listed below are for important fasteners.
ENGINE
Item Q‘ty Thread dia.(mm)
Torque
kgf-m (N-m,
lbf-ft)
Remarks
Cylinder head bolt
Clutch drive plate nut
Drive face nut
Clutch outer nut
A.C.G flywheel nut
Oil check/filler bolt (MXU 50/MX’ER 50)
Oil drain plug
Oil filler bolt (MXU 50 REVERSE)
Exhaust muffler joint lock nut
Exhaust muffler lock bolt
Spark plug
4
1
1
1
1
1
1
1
2
2
BF7X115
39
12
NH10
10
8
8
12
NC6mm
BF8X35
1.6 (16, 11.5)
5.5 (55, 40)
3.8 (38, 27)
3.8 (38, 27)
3.8 (38, 27)
1.2 (12, 9)
2 (20, 15)
2 (20, 15)
1.2 (12, 9)
3.3 (33, 24)
1.5 (15, 11)
FRAME
Item Q‘ty
Thread dia.(mm)
Torque
kgf-m (N-m,
lbf-ft)
Remarks
Steering stem nut
Swing arm nut
Rear wheel nut
Front wheel nut
Rear shock absorber upper mount bolt
Front shock absorber upper mount bolt
1
4
4
4
1
2
14
10
14
14
10
10
7 (70, 50)
4.5 (45, 32)
7 (70, 50)
7 (70, 50)
4 (40, 29)
4 (40, 29)
(Cont’d)
1. GENERAL INFORMATION
1-14
ATV 50
Item Q‘ty
Thread dia.(mm)
Torque
kgf-m (N-m,
lbf-ft)
Remarks
Front shock absorber lower mount bolt
Rear fork axle
Rear hub nut
Rear wheel shaft nut
Rear engine bracket up bolt
Rear engine bracket bolt
Engine hanger bracket bolt
2
1
4
2
1
2
1
10
14
12
32
10
10
10
4 (40, 29)
7 (70, 50)
7 (70, 50)
12 (120, 86)
4 (40, 29)
4 (40, 29)
4.5 (45, 32)
SPECIAL TOOLS
Tool Name Tool No. Memo
Flywheel puller A120E00001
Oil seal and bearing install A120E00014
Crankshaft install A120E00016
Universal holder A120E00017
Crankshaft & crankcase install A120E00024
Crankcase puller A120E00026
Crankshaft Bearing puller A120E00030
Clutch spring compressor A120E00034
Bearing puller A120E00037
Nut wrench A120F00010
LUBRICATION POINTS
ENGINE
Lubrication Points Lubricant
Crankcase sliding & movable parts
Cylinder movable parts
Transmission gear (final gear)
Kick starter spindle bushing
Drive pulley movable parts
Starter pinion movable parts
JASO-FC or API-TC
JASO-FC or API-TC
Gear oil: SAE90#
Grease
Grease
Grease
1. GENERAL INFORMATION
1-15
ATV 50
FRAME
The following is the lubrication points for the frame.
Use general purpose grease for parts not listed.
Apply clean engine oil or grease to cables and movable parts not specified. This will avoid
abnormal noise and rise the durability of the motorcycle.
Steering knuckle/Thrust
Cover/Bush/Colla
r
Steering Column Uppe
r
Rear Brake Cable
Front Brake
camshaft/Oil
Seal/O-ring
Throttle Cable
Front Brake Cable
Steering Column Lowe
r
Front Wheel
Oil Seal
Front Arm Bush
Front Brake
camshaft/Oil
Seal/O-ring
Front Wheel
Oil Seal
Steering knuckle/Thrust
Cover/Bush/Colla
r
Front Arm Bush
1. GENERAL INFORMATION
1-16
ATV 50
Sprocket hub/Rea
r
Axle Hub Collar/Oil
Seal/Bearing
Rear Brake Cam
/
Axle Hub Collar/Oil
Seal/Bearing
Driven Sprocket
Swing arm Thrust
Cove
r
1. GENERAL INFORMATION
1-17
ATV 50
CABLE & HARNESS ROUTING (MX’ER 50)
Throttle Cable
Rear Brake Cable
Right Front Brake Cable
Handlebar Switch Lea
d
Front Brake Cable
Left Front Brake Cable
A.C.G Wire
Starter Motor Wire
Auto Bystarter
1. GENERAL INFORMATION
1-18
ATV 50
Throttle Cable
Rear Brake Cable
Ignition Coil Wire
Fuel Tube
Fuel Filte
r
Oil Meter Wire
Right Front Brake Cable
Left Front Brake Cable
1. GENERAL INFORMATION
1-19
ATV 50
Wire Harness
Rectifier/Regulator
Oil Tube
Resistor
Ignition Coil
Right Front Brake Cable
1. GENERAL INFORMATION
1-20
ATV 50
Battery
Starter Relay
CDI Unit
Fuse
Rear Brake Cable
Breather Hose
Oil Meter Wire
Positive Cable
N
egative Cable
Main Switch
1. GENERAL INFORMATION
1-21
ATV 50
CABLE & HARNESS ROUTING (MXU 50 REVERSE/MXU 50)
Throttle Cable
Rear Brake Light Switch Wire
Front Brake Cable
Handlebar Switch Connectors
Right Front Brake Cable
Left Front Brake Cable
Fuel Tank Breather Hose
Left Headlight
/
Turn Signal Light Connector
Instrument Connecto
r
Horn
Ignition Switch
Connectors
Resisto
r
Right Headlight
/
Turn Signal Light Connectors
Front Brake Light
Switch Wire
Rear Brake Fluid Hose
1. GENERAL INFORMATION
1-22
ATV 50
Ignition Coil
Air Cleane
r
Fuel Valve
Inlet Hose
Oil Inlet Hose
Auto Choke Connecto
r
Starter Motor Connecto
r
Spark Plug Cap
Throttle Cables
N
eutral Switch Wire
(MXU 50 REVERSE)
Rear Brake Hose
1. GENERAL INFORMATION
1-23
ATV 50
Harness Wire
Ignition Coil Cable
Ignition Coil
Fuel Drain Hose
Hazard Unit
Headlight Control Unit
Ignition Coil Wire
Throttle Cable
Starter Motor Cable
ACG Wire
Fuel Unit Connectors
Transmission Case Breathe
r
Hose (MXU 50 REVERSE)
N
eutral Switch Wire (MXU 50 REVERSE)
Oil Outlet Hose
1. GENERAL INFORMATION
1-24
ATV 50
Rectifier/Regulato
r
CDI
Starter Moto
r
Speedometer wire
Harness Wire
ACG Connecto
r
ACG Connecto
r
Oil Level Connectors
Fuel Unit Connectors
Rectifier/Regulator Connecto
r
Pulser Connecto
r
Carburetor Drain Hose
Transmission Case Breather Hose
(MXU 50 REVERSE)
1. GENERAL INFORMATION
1-25
ATV 50
Fuse Box
Start Relay
Tail Light/Brake light Wire
N
egative Cable
Rear Left Turn Signal Light
Rear Right Turn Signal Light Connectors
Positive Cable
Harness Wire
Speed Senso
r
Speedometer Wire
Rear Brake Hose
1. GENERAL INFORMATION
1-26
ATV 50
WIRING DIAGRAM (MX’ER 50) (ON ROAD)
1. GENERAL INFORMATION
1-27
ATV 50
WIRING DIAGRAM (MX’ER 50) (OFF ROAD)
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