KYMCO MX 125, MX150 Service Manual

PREFACE

This Service Manual describes the
technical features and servicing
procedures for the KYMCO MX’er
125/150.

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/INSTALLATION 6
CYLINDER HEAD/VALVES 7
CYLINDER/PISTON 8
DRIVE AND DRIVEN PULLEYS

9

FINAL REDUCTION/TRANSMISSION
SYSTEM

10

CRANKCASE/CRANKSHAFT/
BALANCE SHAFT

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
LIGHTS/SWITCHES 17

ONLY ATV ON ROAD AVAILABLE 18

ENGINE

CHASSIS

ELECTRICAL

EQUIPMENT

The information and contents included
in this manual may be different from
the motorcycle in case specifications
are changed.

1. GENERAL INFORMATION

1-0

MX’er SYSTEM

1

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1

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____________________________________________________________________

____________________________________________________________________

GENERAL INFORMATION

____________________________________________________________________

SERIAL NUMBER---------------------------------------------------------- 1- 1
SPECIFICATIONS---------------------------------------------------------- 1- 2
SERVICE PRECAUTIONS------------------------------------------------ 1- 4
TORQUE VALUES --------------------------------------------------------- 1-12
SPECIAL TOOLS ----------------------------------------------------------- 1-14
LUBRICATION POINTS -------------------------------------------------- 1-15
CABLE & HARNESS ROUTING ---------------------------------------- 1-18
WIRING DIAGRAM-------------------------------------------------------- 1-22
TROUBLESHOOTING----------------------------------------------------- 1-23

1. GENERAL INFORMATION

1-1

MX’er SYSTEM

SERIAL NUMBER

Location of Frame Serial Numbe

r

Location of Engine Serial Numbe

r

1. GENERAL INFORMATION

1-2

MX’er SYSTEM

SPECIFICATIONS

Name & Model No. LA30AA, AB
Motorcycle Name & Type MX’er
Overall length (mm) 1600
Overall width (mm) 980
Overall height (mm) 990
Wheel base (mm) 1120
Engine type O.H.C.
Displacement (cc) 149.4
Fuel Used 92# nonleaded gasoline
Front wheel 74
Net weight (kg) Rear wheel 78
Total 152
Front wheel 80
Gross weight(kg) Rear wheel 82
Total 162
Front wheel 20*7-8
Rear wheel 22*10-8
Ground clearance (mm) 130

Perform-

Breaking distance

(m)(ANSI)

20.6 below

ance

Min. turning radius (m) 3

Starting system

Starting motor

Type Gasoline, 4-stroke
Cylinder arrangement Single cylinder
Combustion chamber type Semi-sphere
Valve arrangement O.H.C., chain drive
Bore x stroke (mm) 62 x 49.5
Compression ratio 9.7:1

Compression pressure
(kg/cm²)

16.0

Max. output (ps/rpm) 11/7500
Max. torque (kg m/rpm) 1.1/5500
Intake

Open 5.5° BTDC

Port

(1mm)

Close 27.5° ABDC

timing

Exhaust

Open 36° BBDC

(1mm)

Close 4° ATDC

Valve clearance

Intake 0.06

(cold) (mm)

Exhaust 0.06

Idle speed (rpm) 1700rpm

Lubrication type

Forced pressure &

wet sump
Oil pump type Inner/outer rotor type
Oil filter type Full-flow filtration
Oil capacity 1.0 liter
Oil exchanging

capacity

0.9 liter

Cooling Type Forced air cooling

Air cleaner type & No Sponge
Fuel capacity 8.1 liters
Type PD
Float lever 14.8mm
Venturi dia.(mm)

φ25

Throttle type PISTON

Type CDI
Ignition timing 15°BTDC/1700rpm

Contact breaker Non-contact point type

Spark plug

NGK

CR8E

Spark plug gap 0.60.7mm
Battery Capacity 12V8AH

Clutch Type CVT

Type Helical gear
Operation

Automatic centrifugal

type

Type Chain drive

Reduction 1st

2.8-0.95

ratio

2nd

7.226

Counter gear ratio

26.902

Front Caster angle

Axle

Trail length

Tire pressure

Fron

t

0.2

(kg/cm²)

Rear 0.25

Turning Left 44°

angle

Right 44°

Brake syste

m

RearDisk brake Drum brake

type

Front Drum brake

Suspension

Fron

t

Swin

g

type

Rear Swing arm

Shock

Front Swing

type

Rear

Swing arm

Frame type SP pipe

Fuel S

y

stem

Carbureto

r

Electrical Equipment

I

g

nition S

y

stem

Tires

Power Drive System

Transmis-

sion Gear

Reduction

Gear

Moving Device

Engine

Damping

Device

Lubrication

S

y

stem

1. GENERAL INFORMATION

1-3

MX’er SYSTEM

SPECIFICATIONS

Name & Model No. LA25AB
Motorcycle Name & Type MX’er
Overall length (mm) 1685
Overall width (mm) 980
Overall height (mm) 990
Wheel base (mm) 1120
Engine type OHC
Displacement (cc) 124
Fuel Used 92# nonleaded gasoline
Front wheel 74
Net weight (kg) Rear wheel 78
Total 152
Front wheel 80
Gross weight(kg) Rear wheel 82
Total 162
Front wheel 20*7-8
Rear wheel 22*10-8
Ground clearance (mm) 130

Perform-

Breaking distance

(m)(ANSI)

20.6 below

ance

Min. turning radius (m) 2.5

Starting system Starting motor
Type Gasoline, 4-stroke
Cylinder arrangement Single cylinder
Combustion chamber type Semi-sphere
Valve arrangement O.H..C., chain drive
Bore x stroke (mm) 56.5 x 49.5
Compression ratio 9.2:1

Compression pressure
(kg/cm²)

14.0

Max. output (ps/rpm) 9.8/7500
Max. torque (kg m/rpm) 0.98/5500
Intake

Open 5.5° BTDC

Port

(1mm)

Close 27.5° ABDC

Timi

n

Exhaust

Open

36° BBDC

(1mm)

Close 4° ATDC

Valve clearance

Intake 0.06

(cold) (mm)

Exhaust 0.06

Idle speed (rpm) 1700rpm

Lubrication type

Forced pressure &

wet sump
Oil pump type Inner/outer rotor type
Oil filter type Full-flow filtration
Oil capacity 1.0 liter
Oil exchanging

capacity

0.9 liter

Cooling Type Forced air cooling

Air cleaner type & No Sponge
Fuel capacity 8.1 liters
Type PD
Piston dia. (mm) 14.8mm
Venturi dia.(mm)

φ25

Throttle type PISTON

Type CDI
Ignition timing 15°BTDC/1700rpm

Contact breaker Non-contact point type

Spark plug

NGK

CR8E
Spark plug gap 0.60.7mm
Battery Capacity 12V8AH

Clutch Type CVT

Type Helical gear
Operation

Automatic centrifugal

type

Type Chain drive

Reduction 1st

2.8-0.95

ratio

2nd

7.226

Counter gear ratio

26.902

Front Caster angle

Axle

Trail length

Tire pressure

Fron

t

0.2

(kg/cm²)

Rear 0.25

Turning Left 44°

angle

Right 44°

Brake syste

m

Rear Disk brake Drum brake

type

Front Drum brake

Suspension

Fron

t

Swin

g

type

Rear Swing arm

Shock

Front Swing

type

Rear

Swing arm

Frame type SP pipe

Fuel S

y

stem

Carbureto

r

I

g

nition S

y

stem

Electrical Equipment

Tires

Power Drive System

Transmis-

sion Gear

Reduction

Gear

Moving Device

Engine

Damping

Device

Lubrication

S

y

stem

1. GENERAL INFORMATION

1-4

MX’er SYSTEM

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

1-5

MX’er SYSTEM

 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

1-6

MX’er SYSTEM

 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.

Confirm
Capacity

1. GENERAL INFORMATION

1-7

MX’er SYSTEM

 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

1-8

MX’er SYSTEM

 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.

No Contact !

1. GENERAL INFORMATION

1-9

MX’er SYSTEM

 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 ti

g

ht!

Do not press
or squeeze
the wire.

1. GENERAL INFORMATION

1-10

MX’er SYSTEM

 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

1-11

MX’er SYSTEM

 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

1. GENERAL INFORMATION

1-12

MX’er SYSTEM

TORQUE VALUES

STANDARD TORQUE VALUES

Item Torque (kgf-m) Ite

m

Torque (kgf-m)

5mm bolt, nut
6mm bolt, nut

8mm bolt, nut
10mm bolt, nut
12mm bolt, nut

14mm bolt, nut

0.450.6

0.81.2

1.82.5

3.04.0

5.06.0

6.08.0

4mm screw
5mm screw

6mm screw, SH bolt
6mm flange bolt and nut
8mm flange bolt and nut
10mm flange bolt and nut

0.150.4

0.30.5

0.71.1

1.01.4

2.43.0

3.54.5

Torque specifications listed below are for important fasteners.

ENGINE

Item Q‘ty Thread dia.(mm) Torque (kgf-m) Remarks

Stud bolt
Oil filter screen cap
Seat ball stopper bolt
Bearing hold
L cover
Stud bolt
Cam holder
Tappet ADJ nut
Pivot tensioner
Lifter tensioner
Lifter tensioner
MISTON oil drive bolt
Driver face
Clutch outer
Oneway clutch
Balancer shaft
ACG flywheel
Spark plug
Drain bolt mission
Drain plug
Clamper wre harness
Motor srart
Oil pump
Oil pump sprocket
Head CYL bolt
Drive plate nut
Startor

4
1
1
1
8
4
4
2
1
2
1
9
1
1
3
1
1
1
1
1
1
2
2
2
2
1
4

8
30
14

6

6

6

8

6

8

6

6

6
12
12

8
16
14

8

8
12

6

6

6

6

6
22

5

0.71.1

1.02.0

4.55.0

1.01.2

1.01.4

0.71.1

1.82.2

1.41.8

0.81.2

1.01.4

0.350.5

0.81.2

5.56.5

5.06.0

2.43.0

4.05.0

5.06.0

1.12.3

0.81.2

2.03.0

0.81.2

0.81.2

0.81.2

0.81.2

0.81.2

5.06.0

0.81.2

1. GENERAL INFORMATION

1-13

MX’er SYSTEM

Item Q‘ty Thread dia.(mm) Torque (kgf-m) Remarks

R cover
Head cover
Cap R cover
Guide star change handle
Sprocket drive plate
Carburetor
Check bolt oil

9
4
1
3
2
2
1

6
6
6
6
6
6

10

0.81.2

0.81.2

0.81.2

0.81.2

1.01.6

0.81.2

1.01.5

FRAME

Item Q‘ty Thread dia.(mm) Torque (kgf-m) 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
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
Exhaust muffler lock bolt

1
4
2
2
1
2
2
1
4
2
1
1
1
2

14
10
14
14
10
10
10
14
12
32
10
10
10

8

6.08.0

4.05.0

6.08.0

6.08.0

3.54.5

3.54.5

3.54.5

6.08.0

6.08.0

11.013.0

3.54.5

3.54.5

3.54.5

3.23.8

1. GENERAL INFORMATION

1-14

MX’er SYSTEM

SPECIAL TOOLS

Tool Name Tool No. Remarks Ref. Page

Flywheel puller E003
Lock nut wrench E009
Valve adjuster E012
Valve spring compressor E040
Oil seal and bearing install E014
Universal holder E017
Flywheel holder E021
Clutch spring compressor E027
Bearing puller E008
Bearing puller E018
Bearing puller E020
Bearing puller E031
Nut wrench F010
Float level gauge

1. GENERAL INFORMATION

1-15

MX’er SYSTEM

LUBRICATION POINTS

ENGINE

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#

1. GENERAL INFORMATION

1-16

MX’er SYSTEM

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/Collar

Steering Column Upper

Front Brake
camshaft/Oil
Seal/O-ring

Steering knuckle/Thrust
Cover/Bush/Colla

r

Front Arm Bush

Front Brake
camshaft/Oil
Seal/O-ring

Steering Column Lower

Front Wheel
Oil Seal

Front Arm Bush

Rear Brake Cable

Throttle Cable

Front Brake Cable

Front Wheel
Oil Seal

1. GENERAL INFORMATION

1-17

MX’er SYSTEM

Swing arm Thrust
Cover

Rear Brake Cam/
Axle Hub Collar/Oil
Seal/Bearing

Sprocket hub/Rear
Axle Hub Collar/Oil
Seal/Bearing

Driven Sprocket

1. GENERAL INFORMATION

1-18

MX’er SYSTEM

CABLE & HARNESS ROUTING

Rear Brake Cable

Throttle Cable

Front Brake Cable

Handlebar Switch Lead

Right Front Brake Cable

Left Front Brake Cable

1. GENERAL INFORMATION

1-19

MX’er SYSTEM

Breather Hose (CYL
Head Cover)

Main Switch

Inlet Hose

Breather
Hose

1. GENERAL INFORMATION

1-20

MX’er SYSTEM

Wire Harness

Breather Hose

Rectifier/Regulato

Ignition Coil

Outlet Hose

Fuse

1. GENERAL INFORMATION

1-21

MX’er SYSTEM

Battery Negative
Cable

Battery

A.C.G Wire
Connector

Breather Hose (CYL
Head Cover)

Positive Cable

CDI Unit

Change Gear Control

Starter Relay

Fuse

1. GENERAL INFORMATION

1-22

MX’er SYSTEM

WIRING DIAGRAM

1. GENERAL INFORMATION

1-23

MX’er SYSTEM

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 CDI unit
Faulty change gear control 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

Spark jumps

Normal

compression

Engine does not

fire

Weak or no spark

Low or no

compression

Engine fires but

does not start

Test cylinder
compression

Start engine by
follow-ing normal
startin

g p

rocedure

Fuel reaches

carburetor

Fuel does not

reach carburetor

Wet spark plug

Dry spark plug

Symptom

Remove spark plug and
inspect again

Probable Cause

1. GENERAL INFORMATION

1-24

MX’er SYSTEM

ENGINE LACKS POWER

Clogged air cleaner
Restricted fuel flow
Clogged fuel tank cap breather hole
Clogged exhaust muffler
Carburetor fuel level too low

Faulty CDI 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

Inspection/Adjustment

Symptom

Engine speed

Correct timin

g

Engine speed does not
increase sufficientl

y

Incorrect timin

g

Check ignition timing
(using a timing light)

Test cylinder compression

Check carburetor for
clogging

Rapidly accelerate or run
at hi

g

h speed

Remove spark plug and
inspect

Check if engine overheats

Check valve clearance

Correct

Incorrec

t

N

ormal

compression

Abnormal

compression

Remove oil dipstick and
check oil level and condition

Engine overheats

Engine does no

t

overheats

Plug not fouled o

r

discolored

Plug fouled or
discolored

Correct and no

t

contaminated

Incorrect o

r

contaminated

Valve train lubricated

prop

erly

Valve train not
lubricated

prop

erl

y

Engine does not knock

Engine knocks

Not clogged

Clogged

Remove cylinder head oil

pip

e bolt and inspect

Probable Cause

1. GENERAL INFORMATION

1-25

MX’er SYSTEM

POOR PERFORMANCE (ESPECIALLY AT IDLE AND LOW SPEEDS)

Faulty CDI 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

Symptom

Correctly adjusted

No air leak

Air leaks

Good spark

Weak or inter-

mittent spark

Incorrectly adjusted

Incorrect timing

Correct timing

Probable Cause Inspection/Adjustment

Check ignition timing

Check carburetor air
screw adjustment

Check carburetor gasket
for air leaks

1. GENERAL INFORMATION

1-26

MX’er SYSTEM

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

Check carburetor jets
for clogging

Check fuel pump for
fuel supply

Correct timing

Incorrect timing

Fuel flows freely

Fuel flow restricted

Correc

t

Incorrec

t

Not clogged

Clogged

Not weakened

Weak spring

Incorrectly adjusted

Correctly adjusted

Check valve clearance

Check valve spring
tension

Probable Cause

Check ignition timing

Check valve timing

1. GENERAL INFORMATION

1-27

MX’er SYSTEM

POOR CHARGING (BATTERY OVER DISCHARGING OR OVERCHARGING)
Undercharging

Inspection/Adjustment Symptom

Probable Cause

Dead battery
Faulty battery

Faulty A.C. generator coil
Broken yellow wire
Shorted pink 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 test
limit voltage of battery
terminals

Connect battery (+) wire
to regulator/rectifier
coupler red wire and
battery (-) wire to engine

g

round and test voltage

Inspection/Adjustment Symptom

Normal voltage

B

attery has voltage
with ignition
switch “ON”

Normal

Voltage does no

t

Normal

Abnormal

B

attery has no
voltage with ignition
switc

h

“ON”

Resistance too high

Normal voltage No voltage

Normal

Abnormal

Measure resistance
between AC generator
coil terminals

Probable Cause

Check regulator/rectifier
coupler for loose
connection

Connect battery (+) wire
to regulator/rectifier
coupler green wire and
battery (-) wire to engine

g

round and test voltage

Check regulator/rectifier
coupler for loose
connection

1. GENERAL INFORMATION

1-28

MX’er SYSTEM

NO SPARK AT SPARK PLUG

Inspection/Adjustment Symptom

Probable Cause

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 change gear control
unit

Faulty ignition coil

Replace with a new
spark plug and inspect
a

g

ain

Check CDI unit coupler
for looseness

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

Good

Good

Check CDI unit with a
CDI unit tester

Loose

Check spark plug cap
and high-tension wire
for looseness