Sym GTS 250, LM25W Series Service Manual

GTS 250

JOYMAX 250

SERVICE MANUAL

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HOW TO USE THIS MANUAL

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SERIAL NUMBER

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This service manual contains the technical data of each component inspection and
repair for the SANYANG LM25W series scooter. The manual is shown with
illustrations and focused on “Service Procedures”, “Operation Key Points”, and
“Inspection Adjustment” so that provides technician with service guidelines.

If the style and construction of the scooter, LM25W series scooter, are different
from that of the photos, pictures shown in this manual, the actual vehicle shall
prevail. Specifications are subject to change without notice.

Service Department

SANYANG INDUSTRY CO., LTD.

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Contents

How To Use This Manual

This service manual describes basic information of different system parts and
system inspection & service for SANYANG LM25W series scooter. In addition,
please refer to the manual contents in detailed for the model you serviced in
inspection and adjustment.

The first chapter covers general information and trouble diagnosis.
The second chapter covers service maintenance information and special tools
manual.
The third to the 11th chapters cover engine and driving systems.
The 12th chapter is cooling system.
The 13th to the 16th chapter is contained the parts set of assembly frame body.
The 17th chapter is electrical equipment.
The 18th chapter is wiring diagram.
Please see index of content for quick having the special parts and system
information.

There are 4 buttons, “Forward”, “Contents”, “How to use this manual” and
“Mechanism Illustrations” on the CD-R version, and can be access to these items
by click the mouse.

If user wants to look for the content of each chapter, selecting the words of each
chapter on the contents can reach to each chapter. There are two buttons,
“Homepage and contents, onto the top line of first page of the each chapter. Thus,
if the user needs to check other chapters, he can click the top buttons to back the
homepage or contents. The content of each chapter can be selected too.
Therefore, when needs to checking the content inside of the chapter, click the
content words of the chapter so that can back to the initial section of the content.
In addition, there is a “To this chapter contents” button at the second page of each
contents so that clicking the button can back to the contents of this chapter.

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Page Content Index

1-1 ~ 1-16
2-1 ~ 2-18
3-1 ~ 3-8
4-1 ~ 4-14
5-1 ~ 5-10
6-1 ~ 6-16
7-1 ~ 7-8

General Information

Service Maintenance Information

Lubrication System

Fuel System

Engine Removal

Cylinder Head / Valve

Cylinder / Piston

Contents

1
2
3
4
5
6

7

8-1 ~ 8-14
9-1 ~ 9-8

10-1 ~ 10-10
11-1 ~ 11-8
12-1 ~ 12-14
13-1 ~ 13-14
14-1 ~ 14-12
15-1 ~ 15-10
16-1 ~ 16-6

“V” Type Belt Driving System / Kick-Starter

Final Driving Mechanism

Alternator

Crankshaft / Crankcase

Cooling System

Body Cover

Front Brake / Front Wheel

Steering / Front Cushion

Rear Brake / Rear Wheel / Rear Cushion

8

9

10
11
12
13
14
15
16

17-1 ~ 17-24

18-1 ~ 18-10

19-1 ~ 19-2

Electrical Equipment

Emission Control System

Electrical Diagram

17

18

19

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Contents

Serial Number

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Contents

Symbols and Marks····························1-1
General Safety····································1-2
Service Precautions···························1-3

Torque Values···································· 1-10
Troubles Diagnosis···························· 1-12
Lubrication Points ····························· 1-16

1. General Information

Specifications·····································1-9

Symbols and Marks

Symbols and marks are used in this manual to indicate what and where the special service are needed, in
case supplemental information is procedures needed for these symbols and marks, explanations will be
added to the text instead of using the symbols or marks.

Warning

Caution

Means that serious injury or even death may result if procedures are not

followed.

Means that equipment damages may result if procedures are not followed.

Limits to use SAE 10W-30 API SG class oil. Warranty will not cover the

1

Engine oil

Grease King Mate G-3 is recommended.

Gear oil

Locking sealant

Oil seal

Renew

Brake fluid

Special tools

Correct

Wrong

damage that caused by not apply with the limited engine oil.

(Recommended oil: KING MATE G-3 oil)

King Mate gear oil serials are recommended. (Bramax HYPOID GEAR OIL

# 140)

Apply sealant; medium strength sealant should be used unless otherwise

specified.

Apply with lubricant.。

Replace with a new part before installation.

Use recommended brake fluid DOT3 or WELLRUN brake fluid.

Special tools

Meaning correct installation.

Meaning wrong installation.

Indication Indication of components.

Directions

Indicates position and operation directions

Components assembly directions each other.

Indicates where the bolt installation direction, --- means that bolt cross
through the component (invisibility).

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To this chapter contents

1. General Information

General Safety

Carbon monoxide

If you must run your engine, ensure the place is
well ventilated. Never run your engine in a closed
area. Run your engine in an open area, if you
have to run your engine in a closed area, be sure
to use an extractor.

Caution

Exhaust contains toxic gas which may cause one
to lose consciousness and even result in death.

Gasoline

Gasoline is a low ignition point and explosive
material. Work in a well-ventilated place, no flame
or spark should be allowed in the work place or
where gasoline is being stored.

Caution

Gasoline is highly flammable, and may explode
under some conditions, keep it away from
children.

Used engine oil

Caution

Prolonged contact with used engine oil (or
transmission oil) may cause skin cancer although
it might not be verified.
We recommend that you wash your hands with
soap and water right after contacting. Keep the
used oil beyond reach of children.

Hot components

Caution

Components of the engine and exhaust system
can become extremely hot after engine running.
They remain very hot even after the engine has
been stopped for some time. When performing
service work on these parts, wear insulated
gloves and wait until cooling off.

Battery

Caution

• Battery emits explosive gases; flame is strictly

prohibited. Keeps the place well ventilated
when charging the battery.

• Battery contains sulfuric acid (electrolyte)

which can cause serious burns so be careful
do not be spray on your eyes or skin. If you
get battery acid on your skin, flush it off
immediately with water. If you get battery acid
in your eyes, flush it off immediately with
water and then go to hospital to see an

ophthalmologist.

• If you swallow it by mistake, drink a lot of

water or milk, and take some laxative such as
castor oil or vegetable oil and then go to see a
doctor.

• Keep electrolyte beyond reach of children.

Brake shoe

Do not use an air hose or a dry brush to clean
components of the brake system; use a vacuum
cleaner or the equivalent to avoid dust flying.

Caution

Inhaling brake shoe or pad ash may cause
disorders and cancer of the breathing system

Brake fluid

Caution

Spilling brake fluid on painted, plastic, or rubber
parts may cause damage to the parts. Place a
clean towel on the above-mentioned parts for
protection when servicing the brake system.
Keep the brake fluid beyond reach of children.

1-2

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Service Precautions

y Always use with SANYANG genuine parts and

recommended oils. Using non-designed parts
for SANYANG ATV may damage the ATV.

y Special tools are designed for remove and

install of components without damaging the
parts being worked on. Using wrong tools may
result in parts damaged.

y When servicing this ATV, use only metric tools.

Metric bolts, nuts, and screws are not
interchangeable with the English system, using
wrong tools and fasteners may damage this
vehicle.

1. General Information

y Never bend or twist a control cable to prevent

unsmooth control and premature worn out.

y Rubber parts may become deteriorated when

old, and prone to be damaged by solvent and oil.
Check these parts before installation to make
sure that they are in good condition, replace if
necessary.

y When loosening a component which has

different sized fasteners, operate with a
diagonal pattern and work from inside out.
Loosen the small fasteners first. If the bigger
ones are loosen first, small fasteners may
receive too much stress.

y Store complex components such as

transmission parts in the proper assemble order
and tie them together with a wire for ease of
installation later.

y Clean the outside of the parts or the cover

before removing it from the ATV. Otherwise, dirt
and deposit accumulated on the part's surface
may fall into the engine, chassis, or brake
system to cause damage.

y Wash and clean parts with high ignition point

solvent, and blow dry with compressed air. Pay
special attention to O-rings or oil seals because
most cleaning agents have an adverse effect on
them.

y Note the reassemble position of the important

components before disassembling them to
ensure they will be reassembled in correct
dimensions (depth, distance or position).

y Components not to be reused should be

replaced when disassembled including gaskets
metal seal rings, O-rings, oil seals, snap rings,
and split pins.

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1. General Information

y The length of bolts and screws for assemblies,

cover plates or boxes is different from one
another, be sure they are correctly installed. In
case of confusion, Insert the bolt into the hole to
compare its length with other bolts, if its length
out side the hole is the same with other bolts, it
is a correct bolt. Bolts for the same assembly
should have the same length.

y Tighten assemblies with different dimension

fasteners as follows: Tighten all the fasteners
with fingers, then tighten the big ones with
special tool first diagonally from inside toward
outside, important components should be
tightened 2 to 3 times with appropriate
increments to avoid warp unless otherwise
indicated. Bolts and fasteners should be kept
clean and dry. Do not apply oil to the threads.

y Remove residues of the old gasket or sealant

before reinstallation, grind with a grindstone if
the contact surface has any damage.

y The ends of rubber hoses (for fuel, vacuum, or

coolant) should be pushed as far as they can go
to their connections so that there is enough
room below the enlarged ends for tightening the
clamps.

Groove

Clamp

Connector

y Rubber and plastic boots should be properly

reinstalled to the original correct positions as
designed.

y When oil seal is installed, fill the groove with

grease, install the oil seal with the name of the
manufacturer facing outside, and check the
shaft on which the oil seal is to be installed for
smoothness and for burrs that may damage the
oil seal.

Manufacturer's name

1-4

Boots

y The tool should be pressed against two (inner

and outer) bearing races when removing a ball
bearing. Damage may result if the tool is
pressed against only one race (either inner race
or outer race). In this case, the bearing should
be replaced. To avoid damaging the bearing,
use equal force on both races.

Both of these examples can result in
bearing damage.

To this chapter contents

y Lubricate the rotation face with specified

lubricant on the lubrication points before
assembling.

y Check if positions and operation for installed

parts is in correct and properly.

y Make sure service safety each other when

conducting by two persons.

1. General Information

y After service completed, make sure all

connection points is secured.
Battery positive (+) cable should be connected
firstly.

y And the two posts of battery have to be greased

after connected the cables.

y Make sure that the battery post caps are

located in properly after the battery posts had
been serviced.

y Note that do not let parts fall down.

y Before battery removal operation, it has to

remove the battery negative (-) cable firstly.
Notre tools like open-end wrench do not contact
with body to prevent from circuit short and
create spark.

y If fuse burned, it has to find out the cause and

solved it. And then replace with specified
capacity fuse.

Capacity
verification

1-5

To this chapter contents

1. General Information

y When separating a connector, it locker has to

be unlocked firstly. Then, conduct the service
operation.

y Do not pull the wires as removing a connector

or wires. Hold the connector body.

y Make sure if the connector pins are bent,

extruded or loosen.

y Insert the terminal completely.

Check if the terminal is covered by the boot.
Do not let boot open facing up.

y Secure wires and wire harnesses to the frame

with respective wire bands at the designated
locations. Tighten the bands so that only the
insulated surfaces contact the wires or wire
harnesses.

y Insert the connector completely.

If there are two lockers on two connector sides,

make sure the lockers are locked in properly.

Check if any wire loose.

y Check if the connector is covered by the twin

connector boot completely and secured
properly.

y Wire band and wire harness have to be

clamped secured properly.

y Do not squeeze wires against the weld or its

clamp.

y Before terminal connection, check if the boot is

crack or the terminal is loose.

1-6

To this chapter contents

y Do not let the wire harness contact with rotating,

moving or vibrating components as routing the
harness.

y Keep wire harnesses far away from the hot

parts.

Never Touch

1. General Information

y Protect wires or wire harnesses with electrical

tape or tube if they contact a sharp edge or
corner. Thoroughly clean the surface where
tape is to be applied.

y Secure the rubber boot firmly as applying it on

wire harness.

y Route wire harnesses to avoid sharp edges or

corners and also avoid the projected ends of
bolts and screws.

y Route harnesses so that they neither pull too

tight nor have excessive slack.

y Never use wires or harnesses which insulation

has been broken. Wrap electrical tape around
the damaged parts or replace them.

y Never clamp or squeeze the wire harness as

installing other components.

Never clamp or
squeeze the wire
harness

Never too tight

1-7

To this chapter contents

1. General Information

y Do not let the wire harness been twisted as

installation.

y Wire harnesses routed along the handlebar

should not be pulled too tight or have excessive
slack, be rubbed against or interfere with
adjacent or surrounding parts in all steering
positions.

y With sand paper to clean rust on connector

pins/terminals if found. And then conduct
connection operation later.

Clean rust

y Before operating a test instrument, operator

should read the operation manual of the
instrument. And then, conduct test in
accordance with the instruction.

Do you know how to set the
instrument to its
measurement position and
the insert locations of its
two probes?

1-8

To this chapter contents

Specifications

MAKER SANYANG MODEL LM25W

Overall Length

Overall Width

Dimension

Weight

Overall Height

Wheel Base

Front

Curb

Weight

Passengers/Weight

Rear

Total

Front

2165 mm

870 mm
1380 mm
1495 mm

69 kg
104 kg
173 kg

Two / 110 kg

91 kg

Suspension

System

Tire

Specifications

Brake System

Performance

1. General Information

Front

Rear

Front

Rear

Front

Rear

Max. Speed

Climb Ability

TELESCOPE

UNlT SWING
110 / 90-13 56P
130 / 70-13 57P

DISK (ø 240 mm)

DISK (ø 220 mm)

Above 115 km/hr

Below 24°

Total

Weight

Type

Installation and

arrangement

Fuel Used

Cycle/Cooling

Bore

Stroke

Cylinder

Number/Arrange

Engine

Displacement

Compression Ratio

ment

Max. HP

Rear

Total

192 kg

283 kg

4-STROKE ENGINE

Vertical, below center,

incline 80°

Above 92 unleaded

4-stroke/ forced air

cooled
71 mm

63 mm

SINGLE CYLINDER

249.4 cc

10.5 : 1

15.4kw / 7500 rpm

Primary

Reduction

Secondary

Reduction

Speedometer

Exhaust Pipe Position and

Direction

Lubrication System

Solid Particulate

n

Exhaust

Concentratio

Reduction

Clutch

Transmission

Horn

Muffler

CO

HC+Nox

Belt

Gear

Centrifugal, dry type

C.V.T., auto speed

change

0 ~ 160 km/hr

80~112 dB/A

Expansion & Pulse

Type

Right side, and

Backward

Forced circulation &

splashing

­Below 7.0 g/km
Below 2.0 g/km

Max. Torque

Ignition

Starting System

21.6 Nm / 6500 rpm

Full transistor ignition

Electrical starter

Catalytic reaction control

E.E.C. √

P.C.V. √

system

√

1-9

To this chapter contents

1. General Information

Torque Values

The torque values listed in above table are for more important tighten torque values. Please see standard
values for not listed in the table.

Standard Torque Values for Reference

Type Tighten Torque Type Tighten Torque

5 mm bolt、nut
6 mm bolt、nut
8 mm bolt、nut
10 mm bolt、nut
12 mm bolt、nut

Engine Torque Values

Item Q’ty Thread Dia. (mm) Torque Value(kgf-m) Remarks

Cylinder stud bolt 4 10 1.0~1.4

Cylinder head nut 4 8 3.6~4.0

Cylinder head right bolt 2 8 2.0~2.4

Cylinder head side cover bolt 2 6 1.0~1.4

Cylinder head cover bolt 4 6 1.0~1.4

Cylinder head stud bolt (inlet pipe) 2 6 1.0~1.4

Cylinder head stud bolt (EX. pipe) 2 8 2.4~3.0

Air inject pipe bolt 4 6 1.0~1.4

Air inject reed valve bolt 2 3 0.07~0.09

Tappet adjustment screw nut 4 5 0.7~1.1 Apply oil to thread

Spark plug 1 10 1.0~1.2

Tensioner lifter bolt 2 6 1.0~1.4

Carburetor insulator bolt 2 6 0.7~1.1

Oil pump screw 2 3 0.1~0.3

Water pump impeller 1 7 1.0~1.4

Engine left cover bolt 9 6 1.1~1.5

Engine oil draining bolt 1 12 3.5~4.5

Engine oil strainer cap 1 30 1.3~1.7

Mission draining bolt 1 8 0.8~1.2

Mission filling bolt 1 10 1.0~1.4

Clutch driving plate nut 1 28 5.0~6.0

Clutch outer nut 1 14 5.0~6.0

Drive face nut 1 14 8.5~10.5

ACG. Flywheel nut 1 14 5.0~6.0

Crankcase bolt 7 6 0.8~1.2

Mission case bolt 7 8 2.6~3.0

Muffler mounting bolt 3 10 3.2 ~3.8

Muffler mounting nut 2 8 1.0 ~1.2

0.45~0.6kgf-m 5 mm screw 0.35~0.5kgf-m

0.8~1.2kgf-m

1.8~2.5kgf-m

3.0~4.0kgf-m

5.0~6.0kgf-m

6 mm screw、SH nut
6 mm bolt、nut
8 mm bolt、nut
10 mm bolt、nut

0.7~ 1.1kgf-m

1.0 ~1.4kgf-m

2.4 ~3.0kgf-m

3.5~4.5kgf-m

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1. General Information

Frame Torque Values

Item Q’ty Thread Dia. (mm) Torque Value (Kg-m) Remarks

Mounting bolt for steering handle
post

Lock nut for steering stem 1 BC1 1.0~2.0

Steering top cone race 1 BC1 2.0~3.0

Front wheel axle nut 1 12 5.0~7.0

Rear wheel axle nut 1 16 11.0~13.0

Front cushion mounting bolt 4 10 3.5~4.5

Rear cushion upper connection bolt 1 10 3.5~4.5

Rear cushion under connection bolt 1 8 2.4~3.0

Rear fork mounting bolt 2 10 4.0~5.0

Brake hose bolt 2 10 3.0~4.0

Brake air-bleeding valve 1 6 0.8~1.0

Front brake disc mounting bolt 5 8 4.0~4.5

Rear brake disc mounting bolt 5 8 4.0~4.5

Brake clipper mounting bolt 2 8 2.9~3.5

Engine hanger link bolt 2 12 7.5~9.5 On frame side

Engine hanger link nut 1 12 7.5~9.5 On engine side

Main standard nut 1 10 4.0~5.0

Air cleaner bolts 2 6 1.0~1.4

1 10 4.0~5.0

1-11

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r

1. General Information

Troubles Diagnosis

A. Engine hard to start or can not be started

Check and adjustment Fault condition Probable causes

Loosen carburetor drain bolt

to check if there is gasoline

inside the carbureto

Fuel supplied tom

carburetor sufficient

Remove spark plug, install it

into spark plug cap, and

perform a spark test against

engine ground.

Check if sparks Weak sparks, no spark

Perform cylinder

compression pressure test.

No fuel is supplied to

carburetor

at all

1. No fuel in fuel tank

2. Check if the pipes, fuel tank to carburetor
and intake vacuum, are clogged.

3. Float valve clogged

4. Lines in fuel tank evaporation system
clogged

5. Malfunction of fuel pump

6. Loosen or damaged fuel pump vacuum
hose

7. Fuel filter clogged

1. Malfunction of spark plug

2. Spark plug foul

3. Malfunction of CDI set

4. Malfunction of AC generator

5. Ignition coil is in open or short circuit

6. Ignition coil leads open or short circuit

7. Malfunction of main switch

Cylinder compression

pressure normal

Re-start by following the

starting procedures

No ignition There are some signs of

Remove the spark plug again

and check it.

Dry spark plug Wet spark plug

Remove carburetor after 30

minutes and connect a hose

onto fuel rich circuit. Then

blow the hose with air

Low compression

pressure or no pressure

ignition, nut engine can

not be started

1. Piston ring seized

2. Malfunction of cylinder valves

3. Worn cylinder and piston ring

4. Cylinder gasket leak

5. Sand hole in compression parts

1. Malfunction of throttle valve operation

2. Air sucked into intake manifold

3. Incorrect ignition timing

1. Fuel level in carburetor too high

2. Malfunction of throttle valve operation

3. Throttle valve opening too wide

1-12

Blowing in normal Blowing clogged

1. Malfunction of automatic by- starter

To this chapter contents

1. General Information

B. Engine run sluggish (Speed does not pick up, lack of power)

Check and adjustment Fault condition Probable causes

Try gradual acceleration and

check engine speed

Check ignition timing
(Using ignition lamp)

Engine speed can be

increased.

Ignition timing correct Incorrect ignition timing

Check cylinder compression

pressure (using compression

pressure gauge)

Compression pressure

correct

Engine speed can not be

increased.

No compression pressure

1. Air cleaner clogged

1. Poor fuel supply

2. Lines in fuel tank evaporation system
clogged

3. Exhaust pipe clogged

4. Fuel level too low in carburetor

5. Fuel nozzle clogged in carburetor.

1. Malfunction of CDI

2. Malfunction of AC alternator

1. Cylinder & piston ring worn out

2. Cylinder gasket leaked

3. Sand hole in compression parts

4. Valve deterioration

5. Seized piston ring

Check if carburetor jet is

clogged

No clogged Clogged

Remove spark plug

No foul or discoloration Fouled and discoloration

Check if engine over heat

Normal Engine overheat

Continually drive in

acceleration or high speed

No knock Knock

1. Remove foreign

1. Remove dirt

2. Incorrect spark plug heat range

1. Piston and cylinder worn out

2. Lean mixture

3. Poor fuel quality

4. Too much carbon deposited in
combustion chamber

5. Ignition timing too advanced

6. Poor circuit on the cooling system

1. Too much carbon deposited in
combustion chamber

2. Lean mixture

3. Poor fuel quality

4. Ignition timing too advanced

1-13

To this chapter contents

1. General Information

C. Engine runs sluggish (especially in low speed and idling)

Check and adjustment Fault condition Probable causes

Check ignition timing
(Using ignition lamp)

Adjust the air screw of

carburetor

Normal Abnormal

Good Poor

Air sucked through

carburetor gasket

No air sucked Air sucked

Remove spark plug, install

spark plug into spark plug

cap and perform spark test

against engine ground

1. Incorrect ignition timing (malfunction

of CDI or AC alternator)

1. Rich mixture (loosen the screw)

2. Lean mixture (tighten the screw)

1. Poor heat insulation gasket

2. Carburetor lock loose

3. Poor intake gasket

4. Poor carburetor O-ring

5. Vacuum hose crack

Good spark Poor

D. Engine runs sluggish (High speed)

Check and adjustment

Check ignition timing

Normal Abnormal

Check for fuel supplying

system in automatic fuel cup

Good Poor

Check if carburetor clogged

Fault condition Probable causes

1. Spark plug fouled

2. Malfunction of CDI

3. Malfunction of AC generator

4. Malfunction of ignition coil

5. Open or short circuit in spark plug

leads

6. Malfunction of main switch

1. Malfunction of CDI

2. Malfunction of AC alternator

1. Insufficient fuel in fuel tank

2. Fuel filter clogged

3. Restricted fuel tank vent

1-14

No clogged Clogged

1. Cleaning

To this chapter contents

E. Clutch, Driving And Driving Pulley

FAULT CONDITIONS

Engine can be started but

motorcycle can not be moved.

Engine running and misfire as

motorcycle initial forward moving or

jumping suddenly (rear wheel
rotating as engine in running)

1. General Information

PROBABLE CAUSES

1. Driving belt worn out or deformation

2. Driving disk damaged

3. Driving pulley spring broken

4. Clutch ling broken

5. Driving slide-shaft gear groove broken

6. Transmission gear damaged

1. Clutch ling spring broken

2. Clutch outer cover stickled with clutch balance
weights

3. Connection parts in clutch and shaft worn out or
burned

1. Driving belt worn out or deformation

Poor initial driving

(Poor climbing performance)

2. Balance weight roller worn out

3. Driving sliding gear shaft worn out

4. Driving disk spring deformation

5. Driving sliding gear shaft worn out

6. Greased in driving belt and sliding gear.

1-15

To this chapter contents

1. General Information

Lubrication Points

Steering shaft bearing

Acceleration cable/
Front & rear brake lever pivot

Seat locker

1-16

Speedometer gear/
front wheel bearing

Side stand shaft

Main stand shaft

Clutch bearing

Home page

Contents

Precautions in Operation······················ 2-1
Periodical Maintenance Schedule ······· 2-2
Engine Oil ·············································· 2-3
Engine Oil Strainer Clean ····················· 2-3
Gear Oil ·················································· 2-4
Fuel Lines / Cable·································· 2-4
Air Cleaner ············································· 2-5
P.C.V. system ········································ 2-6
Valve Clearance····································· 2-6
Carburetor Idle Speed Adjustment ······ 2-7
Ignition System ····································· 2-8

Spark Plug ············································· 2-8

Cylinder Compression Pressure·······2-9
Drive Belt·············································2-9
Steering Handle Top Bearing ············2-10
Cushion ···············································2-10
Disk Brake System ·····························2-11

Brake Light Switch/Starting Inhibitor

Switch··················································2-13
Headlight Beam Distance ··················2-13
Wheel / Tire ·········································2-13
Battery ·················································2-14
Nuts, Bolts Tightness·························2-14

Special Tools List·······························2-15

2. Maintenance Information

Precautions in Operation

Model LM25W

Fuel Tank Capacity 12,000 c.c.

Engine Oil

Transmission
Gear oil

capacity 1,400 c.c.

change 1,200 c.c.

capacity 180 c.c.

change 170 c.c.

2

Capacity of

coolant

Clearance of throttle valve 2~6 mm
Spark plug CR7HSA (gap:0.6~0.7 mm)
〝F〞Mark in idling speed
Full timing advanced BTDC 30º at 6,000 rpm
Idling speed 1,500±100 rpm

Cylinder compression pressure 12 ± 2 Kg/cm²

Valve clearance

Tire dimension Front 110/90-13 56P

Tire dimension Rear 130/70-13 57P

Tire pressure
(cold)

Battery 12V10Ah (MF battery)

Engine + radiator 850 c.c.

Reservoir upper 420 c.c.

BTDC 10º / 2,500 rpm

IN 0.1±0.02 mm

EX 0.15±0.02 mm

single Front: 1.5 Kg/cm² Rear: 2.25 Kg/cm²
Load 90 Kg (full load) Front: 1.5 Kg/cm² Rear: 2.5 Kg/cm²

2-1

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2. Maintenance Information

Periodical Maintenance Schedule

No item

1

☆Air cleaner I C C R

2

☆2nd air jet leaner I C C R

3

☆Fuel filter I I R

4

☆Oil filter C C C

5

☆Engine oil change

Every

300KM

6 Tire pressure
7 Battery inspection
8 Brake & free ply check

9 Steering handle check
10 Cushion operation check
11 Every screw tightening check
12 Gear oil check for leaking
13

☆Spark plug check or change I I R R

14

☆Gear oil change

15 Frame lubrication
16 Exhaust pipe
17

☆Ignition timing I I I I I

18

☆emission check in Idling A I I I I

19

☆Throttle operation I I I I

20

☆Engine bolt tightening I I I I

21

☆CVT driving device(belt﹞ I R

22

☆CVT driving device(roller) C C

23 Lights/electrical equipment/multi-meters
24 Main/side stands & springs
25 Fuel lines
26 Shock absorbers
27 Cam chain
28

☆Valve clearance I A A A

29

☆Crankcase evaporative control system I C C C

30

☆Crankcase blow-by over-flow pipe

31

☆2nd air jet system I I C C

32

☆Evaporative control system I I I

33 Lines & connections in cooling system
34 Coolant reservoir
35 Coolant

Code: I ~ Inspection, cleaning, and adjustment R ~ Replacement C ~ Cleaning (replaced if necessary) L ~ Lubrication

Have your motorcycle checked, adjusted, and recorded maintenance data periodically by your SYM Authorized Dealer to
maintain the motorcycle at the optimum condition

The above maintenance schedule is established by taking the monthly 1,000 kilometers as a reference which ever comes first.

Remarks: 1. These marks “☆” in the schedule are emission control items. According to EPA regulations, these items must be

performed normally periodical maintenance following the use r manual instructions. They are prohibited to be
adjusted or repaired by unauthorized people. Otherwise, SYM is no responsible for the charge.

2. Clean or replace the air cleaner element more often when the motorcycle is operated on dusty roads or in the

Heavily- polluted environment.

3. Maintenance should be performed more often if the motorcycle is frequently operated in high speed and after the
motorcycle has accumulated a higher mileage.

4. Preventive maintenance

a. Ignition system－Perform maintenance and check when continuous abnormal ignition, misfire, after-burn, overheating occur.
b. Carbon deposit removal－Remove carbon deposits in cylinder head, piston heads, exhaust system when power is obvious

lower. Than ever

c. Replace worn out pistons, cylinder head.

1 Month

every

1,000KM

R Replacement for every 1,000 km

I I I I I
I I I I I
I I I I I
I I I
I I I
I I I I I
I I I I I

R Replacement for every 5,000 km

L L

I I I I I

I I I I I
I I I
I I I I

I I I

I I

I I I I I
I I I I I
I

3 month

every

3,000KM

6 month

every

6,000KM

1 year

every

12,000KM

I

Replacement for every 2,000 km

Replacement for every 1 year

I

2-2

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Engine Oil

Turn off engine, and park the motorcycle in flat
surface with main stand.
Check oil level with oil dipstick
So not screw the dipstick into engine as checking.
If oil level is nearly low level, fill out recommended
oil to upper level.

Oil Change

Caution

● Drain oil as engine warmed up so that make
sure oil can be drained smoothly and
completely.

Place an oil pan under the motorcycle, and
remove oil drain bolt.
After drained, make sure washer can be re-used.
Install oil drain bolt.
Torque value: 3.5~4.5kgf-m
Add oil to crankcase (oil viscosity SAE 10W-30)
Recommended using King serial oil.

Engine oil capacity:

Disassembly 1400c.c.
Replacement 1200c.c.

Install dipstick, start the engine for running several
minutes.
Turn off engine, and check oil level again.

Check if engine oil leaks.

Engine Oil Strainer Clean

Drain engine oil out.
Remove oil strainer and spring.
Clean oil strainer.
Check if O-ring can be re-used.
Install oil strainer and spring.
Install oil strainer cap.

Torque value：1.3~1.7kgf-m

2. Maintenance Information

2-3

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2. Maintenance Information

Gear Oil

Oil level inspection
Park the motorcycle on flat surface with main
stand.
Turn off the engine.

Gear Oil Change

Remove oil inspection bolt.
Remove drain plug and drain oil out.
Install the drain plug after drained.

Torque value: 0.8~1.2kgf-m

Add gear oil to specified quantity from the
inspection hole.
Install the inspection bolt.

Torque value: 1.0~1.4kgf-m
Gear Oil Quantity: 170 c.c. when replacing

Make sure that the bolt washer can be re-used,
and install the bolt.
Start engine and run engine for 2-3 minutes.
Turn off engine and make sure that oil level is in
correct level.
Make sure that no oil leaking.

Fuel Lines / Cable

Remove luggage box.
Remove rear carrier.
Remove body covers.
Check all lines, and replace it when they are
deterioration, damage or leaking.

Warning

Drain plug

Oil inspection bolt

2~6 mm

y Gasoline is a low ignition material so any kind

of fire is strictly prohibited as dealing it.

Acceleration Operation

Have a wide open of throttle valve as handle bar in
any position and release it to let back original (full
closed) position.
Check handle bar if its operation is smooth.
Check acceleration cable and replace it if
deteriorated, twisted or damaged.
Lubricate the cable if operation is not smooth
Measure handle bar free play in its flange part.
Free play: 2~6 mm.

Adjustment can be done in either end.
Secondary adjustment is conducted from top side.
Remove rubber boot, loosen fixing nut, and then
adjust it by turning the adjustment nut.

Rubber

Adjustment nut

2-4

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Primary adjustment is conducted from bottom
side.
Loosen fixing nut, and adjust by turning the
adjustment nut.
Tighten the fixing nut, and check acceleration
operation condition.

Air Cleaner

Air Cleaner Element

Remove 8 screws from the air cleaner cover and
then remove the cover.

Remove the body cover.
Loosen bolt from the air cleaner air hose.

Remove 6 screws, and then remove the air
cleaner element.

2. Maintenance Information

Adjustment nut

8 screws

Bolt

6 screws

Caution

y The air cleaner element is made of paper so

do not soap it into water or wash it with
water.

2-5

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2. Maintenance Information

P.C.V. system

Draws out the plug from lower of the breather
chamber hose.
Releases the dry internal deposit.
Every 2,000 kilometers release oil

Caution

A In releases the anal fistula in the transparent
section as worthy of looking at as any deposit
y In the multi- rain or the accelerator in the

situation rides, must reduce the maintenance
traveling schedule

y In releases the anal fistula in the transparent

section as worthy of looking at as any deposit

Valve Clearance

Caution

● Checks and adjustment must be performed

when the engine temperature is below 35℃.

Remove luggage box.
Remove cylinder head cover & side cover.
Remove ignition timing hole cap located in front
upper side of engine right cover
Turn camshaft bolt in C.W. direction and let the “T”
mark on the camshaft sprocket aligns with cylinder
head mark so that piston is placed at TDC position
in compression stroke.

Breather chamber hose

Timing mark

2 bolts

Caution

z Do not turn the bolt in C.C.W. direction to

prevent from camshaft bolt looseness.

Valve clearance inspection and adjustment:

Check & adjust valve clearance with feeler gauge.

Valve clearance (IN)：0.1±0.02 mm.

Valve clearance (EX)：0.15±0.02 mm.

Loosen fixing nut and turn the adjustment nut for
adjustment.

Caution

z Re-check the valve clearance after tightened

the fixing nut.

Special tool: Tappet adjuster

SYM-9001200-08
SYM-9001200-09
SYM-9001200-10

Special tool: Tappet adjuster wrench

SYM-9001200

2-6

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Carburetor Idle Speed Adjustment

Caution

● Inspection & adjustment for idle speed have

to be performed after all parts in engine that
needed adjustment have been adjusted.

● Idle speed check and adjustment have to be

done after engine is being warm up. (It is
enough that operates engine from stop to
running for 10 minutes.)

Park the motorcycle with main stand and warm up
engine.
Connect tachometer (the wire clamp of tachometer
is connected to the high tension cable).
Open carburetor cover from the luggage box.
Turn the throttle valve stopper screw to specified
idle speed

Specified idle speed:1500±100 rpm。

Emission adjustment in idle speed
Warm up the engine for around 10 minutes and
then conduct this adjustment.
Connect the tachometer onto engine.
Adjust the throttle valve stopper screw and let
engine runs in 1500±100 rpm.
Insert the exhaust sampling pipe of exhaust
analyzer into the front section of exhaust pipe.
Adjust the air adjustment screw so that emission
value in idle speed is within standard.
Slightly accelerate the throttle valve and release it
immediately. Repeat this for 2~3 times.
Read engine RPM and value on the exhaust
analyzer. Repeat step 2 to step 4 procedures
until measured value within standard.

Emission standardCO: 3. 0 %↓
HC: 2,000 P.P.M.↓

2. Maintenance Information

Ignition coil cable

Throttle valve stopper screw

Mixture air adjusting screw

2-7

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2. Maintenance Information

Ignition System

Caution

● C.D.I ignition system is set by manufacturer

so it can not be adjusted.

● Ignition timing check procedure is for

checking whether CDI function is in normal or
not.

Remove right side cover.
Remove ignition timing hole cap located in front
upper side of engine right cover.
Connect tachometer and ignition lamp.
Start engine.
As engine in idle speed: 2,500 rpm, aim at the “F”
mark with the ignition lamp. Then, it is means
that ignition timing is correct.
Increase engine speed to 6,000 rpm to check
ignition advance degree. If indent is located within
the ignition advance degrees, it is means that the
ignition advance degree is in normal.
If ignition timing is incorrect, check CDI set, pulse
rotor and pulse generator. Replace it if
malfunction of these parts is found.

Spark Plug

Recommended spark plug: CR8E
Remove luggage box
Remove central cover.
Remove spark plug cap.
Clean dirt around the spark plug hole.
Remove spark plug.
Measure spark plug gap.

Spark plug gap: 0.6~0.7 mm

Carefully bend ground electrode of the plug to
adjust the gap if necessary.
Hold spark plug washer and install the spark plug
by screwing it.
Tighten the plug by turning 1/2 turn more with plug
socket after installed.

Tighten torque: 1.0~1.2kgf-m

Connect spark plug cap

Ground electrode

Central electrode

Spark plug

2-8

0.6~0.7mm

To this chapter contents

Cylinder Compression Pressure

Warm up engine.
Turn off the engine.
Remove luggage box and central cover
Remove spark plug cap and spark plug.
Install compression gauge.
Full open the throttle valve, and rotate the engine
by means of starter motor.

Caution

Rotate the engine until the reading in the gauge
no more increasing.

y Usually, the highest pressure reading will be

obtained in 4~7 seconds.

Compression pressure：12±2 Kg/cm²

Check following items if the pressure is too low:

y Incorrect valve clearance.
y Valve leaking.
y Cylinder head leaking, piston, piston ring and

cylinder worn out.

If the pressure is too high, it means carbon
deposits in combustion chamber or piston head.

Drive Belt

Remove mounting bolt located under air cleaner.
Remove the engine left side cover and the cover.
Check if the belt is crack or worn out.
Replace the belt if necessary or in accord with the
periodical maintenance schedule to replace it.

Width limit: 22.5 mm or above

Clutch Disc Wear

Run the motorcycle and increase throttle valve
opening gradually to check clutch operation.
If the motorcycle is in forward moving and shaking,
check clutch disc condition. Replace it

2. Maintenance Information

Spark plug cap

Teeth

Clutch lining

Compression gauge

Width

Clutch weight

2-9

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2. Maintenance Information

Steering Handle Top Bearing

Caution

● Check all wires and cables if they are

interfered with the rotation of steering handle
bar.

Lift the front wheel out of ground.
Turn handle from right to left alternative and check
if turning is smoothly.
If handle turning is uneven and bending, or the
handle can be operated in vertical direction, then
adjust the handle top bearing.

Cushion

Caution

y Do not ride the motorcycle with poor cushion.
y Looseness, wear or damage cushion will

make poor stability and drive-ability.

Front cushion

Press down the front cushion for several times to
check it operation.
Check if it is damage
Replace relative parts if damage found.
Tighten all nuts and bolts.

Rear Cushion

Press down the front cushion for several times to
check it operation.
Check if it is damage
Replace relative parts if damage found.
Park motorcycle with main stand.
Turn the rear wheel forcefully and check if engine
bracket bushing worn out
Replace the bushing if looseness found.
Tighten all nuts and bolts.

2-10

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Disk Brake System

Brake System Hose

Make sure the brake hoses for corrosion or
leaking oil.

Brake Fluid

Check brake fluid level in the brake fluid reservoir.
If the level is lower than the LOWER limit, add
brake fluid to UPPER limit. Also check brake
system for leaking if low brake level found

Caution

y In order to maintain brake fluid in the reservoir

in horizontal position, do not remove the cap
until handle stop.

y Do not operate the brake lever after the cap

had been removed. Otherwise, the brake
fluid will spread out if operated the lever.

y Do not mix non-compatible brake fluid

together.

2. Maintenance Information

Filling Out Brake Fluid

Tighten the drain valve, and add brake fluid.
Operate the brake lever so that brake fluid
contents inside the brake system hoses.

Added Brake Fluid

Add brake fluid to UPPER limit lever.
Recommended brake fluid: DOT3 or DOT4 WELL
RUN brake fluid.

Caution

Never mix or use dirty brake fluid to prevent from
damage brake system or reducing brake
performance.

Air Bleed Operation

Connect a transparent hose to draining valve.
Hold the brake lever and open air bleeding valve.
Perform this operation alternative until there is no
air inside the brake system hoses.

Caution

Before closing the air bleed valve, do not release
the brake lever.

Air bubble

Master cylinder cap

Diaphragm

LOWER

Brake
Fluid

Drain valve

Transparent hose

2-11

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2. Maintenance Information

Brake Lining Wear

The indent mark on brake lining is the wear
limitation.
Replace the brake lining if the wear limit mark
closed to the edge of brake disc.

Caution

It is not necessary to remove brake hose when
replacing the brake lining.

Remove the brake clipper bolt, and take out the
clipper.

Caution

Do not operate the brake lever after the clipper
removed to avoid clipping the brake lining.

Pry out the brake lining with a flat driver if lining is
clipped.
Remove 2 cotter pins

2 bolts

Brake disk

Brake caliper

Lining

Cotter pins

Caution

● In order to maintain brake power balance, the

brake lining must be replaced with one set.

Remove the brake pad shafts and pads.

2-12

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Brake Light Switch/Starting Inhibitor
Switch

The brake lamp switch is to light up brake lamp as

brake applied.

Make sure that electrical starter can be operated

only under brake applying.

Headlight Beam Distance

Turn on main switch
Headlight beam adjustment. Turn the headlight
adjustment screw to adjust headlight beam high.

Caution

y To adjust the headlight beam follows related

regulations.

y Improper headlight beam adjustment will make

in coming driver dazzled or insufficient
lighting.

Wheel / Tire

2. Maintenance Information

Stop switch

Headlight beam adjustment screws

Caution

● Tire pressure check should be done as cold

engine.。

Appointed tire pressure

Tire size Front tire Rear tire

Tire pressure as

cold engine

(Kg/cm²)

Check if tire surface is ticked with nails, stones or
other materials.
Check if front and rear tires’ pressure is in normal.
Measure tire thread depth from tire central

surface.

Replace the tire if the depth is not come with

following specification

Front tire：1.5 mm
Rear tire：2.0 mm

Load for

under 90 Kg

Full loaded 1.75 2.50

1.75 2.25

2-13

To this chapter contents

2. Maintenance Information

Battery

Open the inner box lid.

Loosen screw & remove the battery cover

Battery cable remove：

1. Disconnect the cable negative terminal (-),

2. then the cable positive terminal (+)

3. Remove the battery from the motorcycle.。

If there is some rust on battery posts, clean it with
steel brush

Install the battery in the reverse procedures of
removal

Caution

y If there is rust on the posts very serious,

spray some hot water on the posts. Then,
clean it with steel brush so that can remove
rust for more easily.

y Apply some grease on the posts after rust

removed to prevent from rust again.

Nuts, Bolts Tightness

Perform periodical maintenance in accord with the
Periodical Maintenance Schedule.
Check if all bolts and nuts on the frame are
tightened securely.
Check all fixing pins, snap rings, hose (pipe)
clamps, and wire holders for security.

2-14

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Special Tools List

NAME

Left crank bearing puller

NO

SYM-9100100

R/L. crank case disassemble

NAME

tool

NO

SYM-1120000-HMA H9A

2. Maintenance Information

Valve cotter remove &

NAME

assembly tool

NO

SYM-1471110/20

NAME

L. Crank shaft puller

NO

SYM-1130000-HMA H9A

R. crank case bearing 6201

NAME

assembles tool

NO

SYM-9614000-HMA 6201

NAME

NAME

Tappet adjusting wrench

NO

SYM-9001200

Left crankshaft & oil seal
assembly socket.

NO

SYM-2341110- HMA RB1

NAME

Tappet adjusting

NO

SYM-9001200-08 09 10

NAME

Rocker arm shaft disassemble

NO

SYM-1445100

NAME

NO

(6204)

Bearing driver 6204

SYM-9110400

NAME

Assembly directs puller

NO

SYM-2341110

NAME

Drive shaft puller

NO

SYM-2341110- HMA RB1

2-15

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2. Maintenance Information

NAME

Inner bearing puller

NO

SYM-6204022

NAME

Clutch nut wrench

NO

SYM-9020200

NAME

NAME

Outer bearing puller

NO

SYM-6204001

Universal holder

NO

SYM-2210100

NAME

Handle stand nut wrench

NO

SYM-5321100

NAME

AC.G. Flywheel puller

NO

SYM-3110000-HMA

NAME

NO

NAME

NO

2-16

Steering head top thread
wrench

SYM-5320010

Air operated bearing puller

SYM-9100410-400 A6205

NAME

Bearing driver HK1516

SYM-9100200-HMA RB1

NO

HK1516

NAME

Oil seal driver 34*52*5

NO

SYM-9125500-HMA

NAME

Bearing puller 6205

NO

SYM-9100400 HMA RAI 6205

Right crankcase cover bearing

NAME

6201 puller
SYM-9614000-HMA RB1 6201

NO

.

To this chapter contents

NAME

NO

Bearing driver 6205
SYM-9615000-6205

NAME

Drive shaft & oil seal (25*40*8)
socket

NO

SYM-9120200-HMA

2. Maintenance Information

NAME

Bearing puller 6303

NO

SYM-6303000-HMA H9A 6303

NAME

NAME

Bearing driver 6201

NO

SYM-9614000-6201

Water pump mechanical seal
driver

NO

SYM-1721700-H9A

(Ø30mm)

NAME

Crankcase bush puller

NO

SYM-1120310

NAME

Water pump bearing driver
6901

NO

SYM-9100100

NAME

NO

(Ø22mm)

Crankcase bush puller
SYM-1120320

NAME

Water pump oil seal driver
(inner)

NO

SYM-9120500-H9A

2-17

To this chapter contents

2. Maintenance Information

Note:

2-18

Home page Contents

Mechanism Diagram······························ 3-1
Precautions in Operation······················ 3-2
Troubleshooting ····································3-2
Engine Oil··············································· 3-3

Mechanism Diagram

Press-In Lubrication

Oil Route

3. Lubrication System

Engine Oil Strainer Clean······················3-3
Oil Pump·················································3-4
Gear Oil···················································3-7

Valve Rocker Arm

Cam Shaft

Spray Lubrication

3

Con-Rod

Spray Lubrication

Press-In Lubrication

Oil Route

Rotate Direction

Oil Pump

Oil Strainer

3-1

To this chapter contents

3. Lubrication System

Precautions in Operation

General Information:

z This chapter contains maintenance operation

for the engine oil pump and gear oil
replacement.

Specifications

Engine oil quantity Disassembly: 1400 c.c.

Change: 1200c.c.

Oil viscosity SAE 10W-30 (Recommended

King serial oils)

Gear oil Disassembly: 180c.c.

Change: 170c.c.

Gear oil viscosity SAE 140
(Recommended SYM Hypoid gear oils)

Unit: mm

Items Standard (mm) Limit (mm)

Inner rotor clearance 0.15 0.20

Oil pump

Clearance between outer rotor and body 0.15~0.20 0.25
Clearance between rotor side and body 0.04~0.09 0.12

Torque value

Torque value oil strainer cap 1.3~1.7kgf-m
Engine oil drain bolt 3.5~4.5kgf-m
Gear oil drain bolt 1.1~1.5kgf-m

Gear oil join bolt 1.0~1.4kgf-m
Oil pump connection screw 0.1~0.3kgf-m

Troubleshooting

Low engine oil level

y Oil leaking
y Valve guide or seat worn out
y Piston ring worn out

Low oil pressure

y Low engine oil level
y Clogged in oil strainer, circuits or pipes
y Oil pump damage

Dirty oil

y No oil change in periodical
y Cylinder head gasket damage
y Piston ring worn out

3-2

To this chapter contents

Engine Oil

Turn off engine, and park the scooter in flat
surface with main stand.
Check oil level with oil dipstick.
So not screw the dipstick into engine as
checking.
If oil level is nearly low level, fill out
recommended oil to upper level.

Oil Change

Caution

Drain oil as engine warmed up so that makes
sure oil can be drained smoothly and completely.

Place an oil pan under the scooter, and remove
oil drain bolt.
After drained, make sure washer can be re-used.
Install oil drain bolt.

Torque value：3.5~4.5kgf-m

Engine Oil Strainer Clean

3. Lubrication System

Drain bolt

Drain engine oil out.
Remove oil strainer and spring.
Clean oil strainer.
Check if O-ring can be re-used.
Install oil strainer and spring.
Install oil strainer cap.

Torque value：1.3~1.7kgf-m

Add oil to crankcase (oil viscosity SAE 10W-30)
Recommended using King serial oil.

Engine oil capacity: 1200c.c. when replacing

Install dipstick, start the engine for running
several minutes.
Turn off engine, and check oil level again.
Check if engine oil leaks.

Oil strainer cap

O-ring

Oil strainer

3-3

To this chapter contents

3. Lubrication System

Oil Pump

Oil Pump Removal

Remove generator and starting gear. (Refer to
chapter 10) 。

Remove cir clip and take out oil pump driving
chain and sprocket.

Make sure that pump shaft can be rotated freely.
Remove 2 screws on the oil pump, and then
remove oil pump.

Clip

Oil Pump Disassembly

Remove the screws on oil pump cover and
remove the cover.
Remove oil pump shaft roller and shaft.

3-4

2 screws

1 screw

Roller

To this chapter contents

Oil Pump Inspection

Check the clearance between oil pump body and
outer rotor.

Limit: 0.25 mm

Check clearance between inner and outer rotors.
Limit: 0.20 mm

Check clearance between rotor side face and
pump body

Limit: 0.12 mm

Oil Pump Re-assembly

Install inner and outer rotors into the pump body.
Align the indent on driving shaft with that of inner
rotor.
Install the oil pump shaft and roller.
Install the oil pump cover and fixing pins properly.

3. Lubrication System

Pins

3-5

To this chapter contents

3. Lubrication System

Tighten the oil pump screw.

Oil Pump Installation

Install the oil pump, and then tighten screws.

Torque value：0.1~0.3kgf-m

Make sure that oil pump shaft can be rotated
freely.

Install oil pump drive chain and sprocket, and
then install cir clip onto oil pump shaft.

Install starting gear and generator.
(Refer to chapter 10)

1 screw

Roller

2 screws

Clip

3-6

To this chapter contents

Gear Oil

Gear Oil Change

Remove oil join bolt.
Remove drain bolt and drain gear oil out.
Install the drain bolt after drained.

Torque value: 1.1~1.5kgf-m

Make sure that the drain bolt washer can be
re-used.
Add oil to specified quantity from the join hole.

Gear Oil Quantity: 170c.c. when replacing

Make sure that the join bolt washer can be
re-used, and install the bolt.

Torque value: 1.0~1.4kgf-m

Start engine and run engine for 2-3 minutes.
Turn off engine and make sure that oil level is in
correct level.
Make sure that no oil leaking.

3. Lubrication System

Gear oil join bolt

Gear oil drain bolt

3-7

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3. Lubrication System

Notes:

3-8

Home page

Contents

Mechanism Diagram ...........................4-1

Precautions in Operation....................4-2

Trouble Diagnosis...............................4-3

Carburetor Remove / Install ...............4-4

Vacuum Chamber................................4-4

Air Cut-off Valve..................................4-6

Mechanism Diagram

Fuel pump

4. Fuel System

Automatic by-starter............................4-7

Float Chamber......................................4-8

Adjustment of Idle Speed....................4-10

Fuel Tank..............................................4-11

Fuel Pump ............................................ 4-13

Air Cleaner............................................4-14

Carburetor

Inlet pipe

4

Fuel tank cap

Fuel strainer

Fuel vapor separator

Fuel unit

Fuel tank

4-1

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4. Fuel System

Precautions in Operation

General Information

Warning

Gasoline is a low ignition point and explosive materials, so always work in a well-ventilated place and

strictly prohibit flame when working with gasoline.

Cautions

y Do not bend off throttle cable. Damaged throttle cable will make unstable drive-ability.
y When disassembling fuel system parts, pay attention to O-ring position, replace with new one as

re-assembly

y There is a drain screw in the float chamber for draining residual gasoline.

y Do not disassemble air cut valve arbitrarily.

Specification

ITEM LM25W

Carburetor diameter Ø28.8 mm

I.D. number CVK122B

Fuel level 18.5 mm

Main injector # 122

Idle injector # 38

Idle speed 1500±100 rpm

Throttle handle clearance 2~6 mm

Pilot screw 2±1/2 turns

Tool
Special service tools

Vacuum/air pressure pump
Fuel level gauge

4-2

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Trouble Diagnosis

Poor engine start

y No fuel in fuel tank
y Clogged fuel tube
y Too much fuel in cylinder
y No spark from spark plug(malfunction of ignition

system )

y Clogged air cleaner
y Malfunction of carburetor chock
y Malfunction of throttle operation

Stall after started

y Malfunction of carburetor chock
y Incorrect ignition timing
y Malfunction of carburetor
y Dirty engine oil
y Air existing in intake system
y Incorrect idle speed

4. Fuel System

Mixture too lean

y Clogged fuel injector
y Vacuum piston stick and closed
y Malfunction of float valve
y Fuel level too low in float chamber
y Clogged fuel tank cap vent
y Clogged fuel filter
y Obstructed fuel pipe
y Clogged air vent hose
y Air existing in intake system

Mixture too rich

y Clogged air injector
y Malfunction of float valve
y Fuel level too high in float chamber
y Malfunction of carburetor chock
y Dirty air cleaner

Rough idle

y Malfunction of ignition system
y Incorrect idle speed
y Malfunction of carburetor
y Dirty fuel

Intermittently misfire as acceleration

y Malfunction of ignition system

Late ignition timing

y Malfunction of ignition system
y Malfunction of carburetor

Power insufficiency and fuel consuming

y Fuel system clogged
y Malfunction of ignition system

4-3

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4. Fuel System

Carburetor Remove / Install

Removal

Remove luggage box.
Drain out fuel in the float chamber.

Disconnect the fuel hose, vacuum hose.
Disconnect the auto by-start and heater couplers.
Loosen the adjustment nut and fixing nut of throttle
valve cable, and release the cable from
carburetor.
Release the clamp strip of carburetor, and then
remove the carburetor.

Throttle cable

Fuel pipe

Installation

Install in reverse order of removal procedures.

Vacuum Chamber

Removal

Loosen drain screw, and drain out residual fuel in
float chamber.
Remove screws (2 screws) of vacuum chamber
cover and the cover.

Remove compress spring and vacuum piston.

Spring

Clamp

2 screws

Vacuum diaphragm

4-4

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Remove fuel needle seat, spring, and injector
needle.

Inspection

Check if the vacuum piston and needle for wear
out, crack or other damage.
Check if the diaphragm for damage or crack.

Caution

● Do not damage vacuum diaphragm.

Installation

Install in reverse order of removal procedures.

4. Fuel System

Piston

Needle seat

Spring

Needle

2 screws

4-5

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4. Fuel System

Air Cut-off Valve

Removal

Removal the throttle cable seat (2 screws)

Remove the screws (2 screws) of the air cut-off
valve and its cover.

2 screws

2 screws

Remove the spring and vacuum diaphragm.

Check if the diaphragm for deterioration or crack.

Installation

Install the valve as reverse order of removal.

Caution

z Do not damage the vacuum diaphragm or in

opposite installation direction.

4-6

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Automatic by-starter

Inspection

Turn off engine and waiting for over 10 minutes for
cooling.
Check resistance across the two terminals of the
automatic by-starter.

Resistance value: Max. 10Ω (Measured after
engine stopped for more than 10 minutes)

Replace the automatic by-starter with a new one if
resistance value exceeds standard.

Remove the carburetor, allow it to cool off for 30
minutes.
Connect a pressure tester form air pump.
Connect fuel rich circuit.
Pump compressed air to the circuit.
Replace the automatic by-starter if the circuit
clogged.

Connect battery posts (12V) to starter’s
connectors. After 5 minutes, test the rich circuit
with compressed air.
If air flow through the circuit, then replace the
by-starter.

Removal

Remove fixing plate screw, and then remove the
plate and automatic by-starter from carburetor.

4. Fuel System

1 screw

Valve inspection

Check if automatic by-starter and valve needle for
damage or wear out.

Installation

Install automatic by-starter to the carburetor body.
Install fixing plate to the upper groove of automatic
by-starter, and install its flat surface to carburetor.
Install screw and tighten it.

Caution

z Align the round point of the starter with the

screw hole of air intake side.

4-7

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4. Fuel System

Float Chamber

Disassembly

Remove 3 mounting screws and remove float
chamber cover.

Remove the fuel level plate, float pin, float and
float valve.

Inspection

Check float valve and valve seat for damage,
blocking.
Check float valve for wearing, and check valve
seat face for wear, dirt.

3 screws

1 screw

Float pin

Main jet

Slow jet

Float

Float

Caution

In case of worn out or dirt, the float valve and
valve seat will not tightly close causing fuel level
to increase and as a result, fuel flooding. A worn
out or dirty float valve must be replaced with a
new a new one.

Remove main jet, needle jet holder, needle jet,
slow jet and air adjustment screw.

Caution

Take care not to damage jets and adjust screw.

y Before removing adjustment screw, turn it all

the way down and note the number of turns.

y Does not turn adjust screw forcefully to avoid

damaging valve seat face.

Clean jets with cleaning fluid. Then use
compressed air to blow the dirt off.
Blow carburetor body passages with compressed
air.

1 screw

Needle jet

Float valve

Needle jet holder

Slow jet

Main jet

4-8

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Assembly

Install main jet, needle jet holder, needle jet, slow
jet and air adjustment screw.

Caution

Set the air adjustment screw in according to
number of turns noted before it was removed.

Install the float valve, float, and float pin.

Checking fuel level

Air adjustment screw

1 screw

Main jet

4. Fuel System

Float

Slow jet

Caution

y Check again to ensure float valve, float for

proper installation.

y To ensure correct measurement, position the

float meter in such a way so that float chamber
face is vertical to the main jet.

Fuel level: 18.5mm

Installation of carburetor

Install carburetor in the reverse order of removal.
Following adjustments must be made after
installation.

˙Throttle cable adjustment.
˙Idle adjustment

Throttle cable adjustment nuts

4-9

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4. Fuel System

Adjustment of Idle Speed

Caution

y Air screw was set at factory, so no adjustment

is needed. Note the number of turns it takes to
screw it all the way in for ease of installation.

y The parking brake must be used to stop the

scooter to perform the adjustments.

Use a tachometer when adjusting engine RPM.
Screw in air adjustment screw gently, then back up
to standard turns.

Standard turns: 2±1/2 turns

Warm up engine; adjust the throttle stopper screw
of throttle valve to standard RPM.

Idle speed rpm: 1500±100 rpm

Connect the hose of exhaust analyzer to exhaust
front end. Press test key on the analyzer.
Adjust the pilot screw and read CO reading on the
analyzer

CO standard value: 1.3~2.0 %

Accelerate in gradual increments; make sure rpm
and CO value are in standard value after engine
running in stable. If rpm and CO value fluctuated,
repeat the procedures described above for
adjusting to standard value.

Throttle cable adjustment nuts

Throttle cable adjustment nuts

Air adjustment screw

4-10

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Fuel Tank

Fuel unit removal

Remove the left and right side covers.
Open seat and remove the luggage box.
Remove rear carrier.
Remove the left and right body covers.
Remove the foot pedal (please refer to chapter 13
for these components above.)

Remove fuel unit coupler, and then remove fuel
unit (4 screws).

Caution

˙Do not bend the float arm of fuel unit
˙Do not fill out too much fuel to fuel tank.

Fuel unit inspection (Refer to electrical equipment

chapter 17).

Fuel unit coupler

4. Fuel System

4 bolts

Fuel unit installation

Install the fuel unit in the reverse order of removal.

Caution

Do not forget to install the gasket of fuel unit or
damage it.

Fuel tank removal

Remove the left and right side covers.
Open seat and remove the luggage box.
Remove rear carrier.
Remove the left and right body covers.
Remove the foot pedal (please refer to chapter 13
for these components above.)
Remove under cover (4 bolts).
Disconnect fuel unit coupler.
Remove the fuel inlet tubes.

Remove the
Remove fuel tank front and rear side 4 bolts, and
then remove fuel tank.

vapor tube, fuel outlet tube.

Fuel tube

Fuel unit

Fuel tube

Vapor tube

4-11

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4. Fuel System

Remove fuel tank upper bolts (2 bolts).

Remove fuel tank under bolt (1 bolt).

Remove fuel tank.

2 bolts

1 bolt

Installation

Install the fuel tank in the reverse order of removal.

4-12

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Fuel Pump

Inspection

Remove the left side cover and floor panel side
cover.
Warm up the engine and adjust idle speed.
Remove fuel hose from carburetor and then wait
for 5 minutes.
Measure the output of fuel pump. Its output time
is 10 seconds.

Output quantity: Min. 20 c.c.

If the output quantity is lower than 20 c.c., check
fuel hose, vacuum hose and fuel filter.

Removal / Installation

Remove floor plate.

Remove fuel inlet, outlet and vacuum tube.
Remove 2 nuts and fuel pump.
Install the fuel pump in the reverse order of
removal procedures.

2 nuts

4. Fuel System

Clamp

Outlet tube

Inlet tube

Vacuum tube

4-13

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4. Fuel System

Air Cleaner

Removal

Loosen the clamp strip of air cleaner and
carburetor, and then remove the vapor hose.

Remove the air cleaner (3 bolts).

Installation

Install the tank in the reverse order of removal.

Cleaning air cleaner element

Remove the air cleaner cover (8 screws).

Remove element mounting screws (6 screws).
Remove the air cleaner element.
With compressed air to cleaning dirty around the
element. Replace it if it is too dirty to clean.

8 screws

6 screws

2 bolts

1 bolt

Caution

The air cleaner element is made of paper so do
not soap it into water or wash it with water.

Install the element onto the element seat and then
install the air cleaner cover.

4-14

Home page

Contents

Operational Precautions····················· 5-1
Engine Removal ·································· 5-2
Engine Hanger····································· 5-6

5. Removal & Installation of Engine

Rear Fork··············································5-7
Removal of Engine Bush·····················5-9
Installation of Engine··························· 5-10

Operational Precautions

General Information

y Engine must be supported by a bracket or adjustable tool in height.
y The following parts can be serviced with the engine installed on the frame.

1. Carburetor

2. Driving disk, driving belt, clutch, and transporting disk

3. Final reduction gear mechanism

4. AC. Generator

Specification

Item LM25W

Replacement 1,200 c.c.

Engine Oil Capacity

Disassemble 1,400 c.c.

5

Replacement 170 c.c.

Gear Oil Capacity

Disassemble 180 c.c.

Engine + radiator 850 c.c.

Capacity of coolant

Reservoir upper 420 c.c.

Torque Values

Engine hanger bolt (frame side) 7.5~9.5kgf-m
Engine hanger nut (engine side) 7.5~9.5kgf-m
Bolt of rear cushion upper connection 3.5~4.5kgf-m
Bolt of rear cushion lower connection 2.4~3.0kgf-m
Rear wheel axle nut 11.0~13.0kgf-m

5-1

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5. Removal & Installation of Engine

Engine Removal

Open inner box cover.
Remove battery cover (1 screw).
Remove the battery negative (-) cable.
Remove the battery positive (+) cable.

Open the seat.
Remove the luggage box (6 bolts, 2 screws).
(Refer to chapter 13)

Remove right and left side covers (4 screws on
each side.).
Remove rear carrier (4 bolts).
Remove body cover (4 screws & 1 coupler).
(Refer to chapter 13)

Remove the power coupler of auto by-starter.
Remove the spark plug cap.

Positive

Auto by-starter coupler

Negative

5-2

Spark plug cap

To this chapter contents

Remove the generator power wire and pulse
generator connector.
Remove the starter motor wire.

Remove engine blow-by pipe.

Remove the fuel line, vacuum hose, and throttle
valve cable from the carburetor.
Loosen the clamp strip of air cleaner and
carburetor, and then remove the air cleaner hose.

Remove the air cleaner inlet pipe connection bolt
(1 bolt).

5. Removal & Installation of Engine

Couplers of the generator and
pulse generator

Starter motor wire

Engine blow-by pipe

Clamp strip

1 Bolt

5-3

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5. Removal & Installation of Engine

Remove the air cleaner connection bolts (2 bolts).
Remove the air cleaner.

Remove the exhaust muffler (3 bolts, 2 nuts).

Drain out coolant, and remove coolant inlet hose.

Remove the coolant inlet hose and thermo-sensor
wire.

3 bolts

Drain bolt

Outlet hose

2 bolts

2 nuts

Inlet hose

5-4

Thermo-sensor wire

To this chapter contents

Remove rear brake hose clamp and rear brake
caliper.

Remove the right rear cushion lower bolt (1 bolt).
Remove the rear fork bolts (2 bolts).
Remove the rear wheel axle nut (1 nut).

Remove the rear fork and rear axle collars.

Remove left rear cushion lower bolt (1 bolt).

5. Removal & Installation of Engine

2 bolts

Brake hose clamp

Rear axle nut

1 bolt

2 bolts

1 bolt

5-5

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5. Removal & Installation of Engine

With a bracket to support the engine to prevent
from it damage by falling down as removing the
engine.
Remove frame side engine hanger bolts (each
side 1 bolt), and then remove engine.

Engine Hanger

Removal

Remove the engine side bolts of engine hanger. (1
bolt on each side)
Remove the engine hanger.
Check if the engine hanger bush and cushion
rubber for damage. If so, replace with new ones.

Installation

Tighten the bolts and nuts of engine hanger.

Engine hanger nut:
Torque Value: 7.5~9.5kgf-m

Engine side bolt

Frame side bolt

5-6

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Rear Fork

Bearing Inspection

Check bearings on rear fork.
Rotate bearing inner ring with fingers.
Check if bearing can be turned in smooth and
silent, and also check if bearing outer ring is
mounted on rear fork tightly.
If bearing rotation is uneven, noising, or loose
bearing mounted, then replace it.

Bearing removal

Remove bearing mounting cir clip.
Drive the bearing out of the rear fork.

Bearing installation

Install new rear axle bearing and baring puller into
rear fork.

Special Service Tools:
Rear fork bearing puller SYM-6303000-6303

Install the washer of the 6303 bearing puller.

5. Removal & Installation of Engine

Cir clip

6303 bearing puller

6303 bearing puller washer

5-7

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5. Removal & Installation of Engine

Install assembly directs puller bearing puller.

Special Service Tools:
Assembly directs puller

Use screw driver holder bearing puller lower pa rt, and
turn the bearing puller upper part to inst all the rear fork
bearing.

Install bearing mounting cir clip.

SYM-2341110

Bearing puller

Cir clip

5-8

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Removal of Engine Bush

If engine hanger frame and the cushion rubber of
rear cushion bush damaged. Then, with the bush
remover / presser, ø28mm & ø20mm, to press the
bush out, and replace it with new one.

Engine hanger bush: ø 28mm
Rear cushion bush: ø 20mm

Pressing out

Place the detent section of the bush remover
toward the bush, and drive both the pressing ring
and bolt in to press the bush out.

Special Service Tools:

Crankcase bush remover/presser SYM-1120310
Crankcase bush remover/presser SYM-1120320

Pressing In

Place the flat section of the remover toward the
bush, and then drive the bush, pressing ring, and
bolt in to install the bush.

5. Removal & Installation of Engine

5-9

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5. Removal & Installation of Engine

Installation of Engine

Install the engine according to the reversing order
of removal.

Caution

z Note both feet and hands safety for

squeezing as engine installation.

z Do not bent or squeeze each wires or hose.
z Route all cables and wires in accordance with

the routine layout.

Engine hanger nut:
Torque Value: 7.5~9.5kgf-m

Rear cushion bolt:
Torque Value: upper: 3.5~4.5kgf-m

Rear wheel axle nut:
Torque Value: 11.0~13.0kgf-m

Under: 2.4~3.0kgf-m

5-10

Home page

Contents

Mechanism Diagram··························· 6-1
Precautions in Operation··················· 6-2
Troubleshooting·································· 6-3
Cylinder Head Removal······················ 6-4
Cylinder Head Disassembly··············· 6-6
Cylinder Head Inspection··················· 6-8

Mechanism Diagram

1.0~1.4kgf-m

1.0~1.4kgf-m

6. Cylinder Head / Valve

Valve Stem Replacement··················· 6-10
Valve Seat Inspection and Service··· 6-11
Cylinder Head Reassembly··············· 6-13
Cylinder Head Installation················· 6-14
Valve Clearance Adjustment············· 6-16

1.0~1.4kgf-m

1.0~1.2kgf-m

1.0~1.4kgf-m

6

0.7~1.1kgf-m

1.0~1.4kgf-m

3.6~4.0kgf-m

2.4~3.0kgf-m

1.0~1.2kgf-m

1.0~1.4kgf-m

6-1

To this chapter contents

6. Cylinder Head / Valve

Precautions in Operation

General Information

y This chapter is contained maintenance and service for cylinder head, valve, and camshaft as well as

rocker arm.

y Cylinder head service can be carried out when engine is in frame.

Specification

Item Standard Limit

Compression pressure 12±2 kg/cm2 ---

Camshaft Height of cam lobe

ID of valve rocker arm 11.982~12.000 12.080

Rocker arm

OD of valve rocker arm shaft 11.966~11.984 11.936

OD of valve stem

Intake 34.880 34.860
Exhaust 34.740 34.725

Intake 4.975~4.990 4.900
Exhaust

4.950~4.975

4.900

ID of valve guide 5.000~5.012 5.030
Clearance between

valve stem and guide

Valve

Free length of valve
spring

Valve seat width 1.600 ---

Valve clearance

Tilt angle of cylinder head --- 0.050

Intake 0.010~0.037 0.080
Exhaust 0.025~0.062 0.100
Inner 38.700 35.200
outer 40.400 36.900

Intake 0.10±0.02mm --­Exhaust 0.15±0.02mm ---

Torque Value

Cylinder head cover bolt 1.0~1.4kgf-m
Exhaust pipe stud bolt 2.4~3.0kgf-m
Cylinder head bolt 1.0~1.4kgf-m
Cylinder head Nut 3.6~4.0kgf-m
Sealing bolt of cam chain auto-tensioner 0.8~1.2kgf-m
Bolt of cam chain auto-tensioner 1.2~1.6kgf-m
Cylinder side cover bolt 1.0~1.4kgf-m
Cam sprocket bolt 1.0~1.4kgf-m
Tappet adjustment screw nut 0.7~1.1kgf-m
Spark plug 1.0~1.2kgf-m

Tools
Special service tools

Valve reamer: 5.0mm
Valve guide driver: 5.0mm
Valve spring compressor

6-2

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6. Cylinder Head / Valve

Troubleshooting

Engine performance will be affected by troubles on engine top parts. The trouble usually can be
determined or by performing cylinder compression test and judging the abnormal noise generated.

Low compression pressure

1. Valve

y Improper valve adjustment
y Burnt or bent valve
y Improper valve timing
y Valve spring damage
y Valve carbon deposit.

2. Cylinder head

y Cylinder head gasket leaking or damage
y Tilt or crack cylinder

3. Piston

y Piston ring worn out.

High compression pressure

y Too much carbon deposit on combustion chamber or piston head

Noise

y Improper valve clearance adjustment
y Burnt valve or damaged valve spring
y Camshaft wear out or damage
y Chain wear out or looseness
y Auto-tensioner wear out or damage
y Camshaft sprocket
y Rocker arm or rocker arm shaft wear out

6-3

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6. Cylinder Head / Valve

Cylinder Head Removal

Remove engine. (Refer to chapter 5)

Remove 2 bolts of thermostat and then remove
the thermostat.
Remove hole bolt and spring for the cam chain
tensioner.
Loosen 2 bolts, and then remove tensioner.
Remove thermostat (2 bolts).

Remove Air Injection system (AI) pipe mounting
bolts.
Remove spark plug.

Remove cylinder head cover (4 bolts).

Tensioner bolts

Thermostat bolts

4 bolts

4 bolts

6-4

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Remove the side cover mounting blots of cylinder
head, and then take out the side cover.

Remove left crankcase cover, and turn the
Turn the drive face, and align the timing mark on
the sprocket with that of cylinder head, piston is at
TDC position.
Remove cam sprocket bolts and then remove the
sprocket by prying chain out.

Remove the 2 cylinder head mounting bolts from
cylinder head right side, and then remove 4 nuts
and washers from cylinder head upper side.
Remove the cylinder head.

Remove cylinder head gasket and 2 dowel pins.
Remove chain guide.
Clean up residues from the matching surfaces of
cylinder and cylinder head.

3 bolts

Bolt ×2

6. Cylinder Head / Valve

Timing mark

2 bolts

2 dowel pins

4 nuts

Caution

y Do not damage the matching surfaces of

cylinder and cylinder head.

y Avoid residues of gasket or foreign materials

falling into crankcase as cleaning.

Cam chain guide

6-5

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6. Cylinder Head / Valve

Cylinder Head Disassembly

Remove cam shaft setting plate (1 bolt).

Remove rocker arm shafts and rocker arms.

Special Service Tool:
Rocker arm and cam shaft puller SYM-1445100

Remove cam shafts.

Special Service Tool:
Rocker arm and cam shaft puller SYM-1445100

Use a valve cotter remove & assembly tool to
press the valve spring, and then remove valves.

1 bolt

Cam shaft setting plate

Rocker arm shaft and

cam shaft puller

Cam shafts

Rocker arm

shaft and cam
shaft puller

Caution

y In order to avoid loosing spring elasticity, do not

press the spring too much. Thus, press length
is based on the valve cotter in which can be
removed.

Special Service Tool:
Valve cotter remove & assembly tool
SYM-1471110-SY125

6-6

Valve cotter remove

and assembly tool

To this chapter contents

Remove valve cotters, spring retainers, springs
and valves.

Remove valve stem seals.

Clean carbon deposits in combustion chamber.
Clean residues and foreign materials on cylinder
head matching surface.

6. Cylinder Head / Valve

Inlet valve

Exhaust valve

Inner spring

Outer spring

Spring retainer

Cotter

Valve stem seals

Caution

Do not damage the matching surface of cylinder
head.

6-7

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6. Cylinder Head / Valve

Cylinder Head Inspection

Check if spark plug and valve holes are cracked.
Measure cylinder head warp with a straightedge
and thickness gauge.

Service limit: 0.05 mm

Camshaft

Inspect cam lobe height for damaged.

Service Limit:

IN: Replacement when less than 34.860mm
EX: Replacement when less than 34.725mm

Inspect the camshaft bearing for looseness or
wear out. If any damage, replace whole set of
camshaft and bearing.

Rocker Arm

Measure the cam rocker arm I.D., and wear or
damage, oil hole clogged?

Service Limit: Replace when it is less than

12.080 mm.

Rocker Arm Shaft

Measure the active O.D. of the cam rocker arm
shaft and cam rocker arm.

Service Limit: Replace when it is less than

11.936 mm.

Calculate the clearance between the rocker arm
shaft and the rocker arm.

Service Limit: Replace when it is less than 0.10
mm.

6-8

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Valve spring free length

Measure the free length of intake and exhaust
valve springs.

Service limit:
Inner spring 35.20 mm
Outer spring 36.90 mm

Valve stem

Check if valve stems are bend, crack or burn.
Check the operation condition of valve stem in
valve guide, and measure & record the valve stem
outer diameter.

Service Limit: IN: 4.90 mm

EX: 4.90 mm

Valve guide

6. Cylinder Head / Valve

Caution

Before measuring the valve guide, clean carbon
deposits with reamer.

Tool: 5.0 mm valve guide reamer

Measure and record each valve guide inner
diameters.

Service limit: 5.03 mm

The difference that the inner diameter of valve
guide deducts the outer diameter of valve stem is
the clearance between the valve stem and valve
guide.

Service Limit: IN→0.08 mm

EX→0.10 mm

Caution

If clearance between valve stem and valve guide
exceeded service limit, check whether the new
clearance that only replaces new valve guide is
within service limit or not. If so, replace valve
guide.

Correct it with reamer after replacement.
If clearance still exceeds service limit after
replaced valve guide, replace valve stem too.

5.0 mm valve guide reamer

Caution

It has to correct valve seat when replacing valve
guide.

6-9

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6. Cylinder Head / Valve

Valve Stem Replacement

Heat up cylinder head to 100~150 ℃ with heated
plate or toaster.

Caution

y Do not let torch heat cylinder head directly.

Otherwise, the cylinder head may be deformed
as heating it.

y Wear on a pair of glove to protect your hands

when operating.

Hold the cylinder head, and then press out old
valve guide from combustion chamber side.

Tool: Valve guide driver: 5.0 mm

Caution

y Check if new valve guide is deformation after

pressed it in.

y When pressing in the new valve guide, cylinder

head still have to be kept in 100~150

℃.

Valve guide driver

5.0mm

Valve guide driver

5.0 mm

Adjust the valve guide driver and let valve guide
height is in 13 mm.
Press in new valve guide from rocker arm side.

Tool: Valve guide driver: 5.0 mm

Wait for the cylinder head cooling down to room
temperature, and then correct the new valve guide
with reamer.

Caution

y Using cutting oil when correcting valve guide

with a reamer.

y Turn the reamer in same direction when it be

inserted or rotated.

Correct valve seat, and clean up all metal residues
from cylinder head.

Tool: Valve guide reamer: 5.0 mm

Valve guide reamer 5.0 mm

6-10

To this chapter contents

Valve Seat Inspection and Service

Clean up all carbon deposits onto intake and
exhaust valves.
Apply with emery slightly onto valve contact face.
Grind valve seat with a rubber hose or other
manual grinding tool.

Caution

y Do not let emery enter into between valve stem

and valve guide.

y Clean up the emery after corrected, and apply

with engine oil onto contact faces of valve and
valve seat.

Remove the valve and check its contact face.

Caution

Replace the valve with new one if valve seal is
roughness, wear out, or incomplete contacted
with valve seat.

Valve seat inspection

If the valve seat is too width, narrow or rough,
corrects it.

Valve seat width

Service limit: 1.6mm

Check the contact condition of valve seat.

Valve seat grinding

The worn valve seat has to be ground with valve
seat chamfer cutter.
Refer to operation manual of the valve seat
chamfer cutter.
Use 45° valve seat chamfer cutter to cut any rough
or uneven surface from valve seat.

Caution

After valve guide had been replaced, it has to be
ground with 45° valve seal chamfer cutter to
correct its seat face.

Use 32° cutter to cut a quarter upper parts out.

6. Cylinder Head / Valve

Valve seat width

Roughness

45°

Old valve seat width

32°

6-11

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6. Cylinder Head / Valve

Use 60° cutter to cut a quarter lower parts out.
Remove the cutter and check new valve seat.

Use 45° cutter to grind the valve seat to specified
width.

Caution

Make sure that all roughness and uneven faces
had been ground.

Grind valve seat again if necessary.

Coat the valve seat surface with red paint.
Install the valve through valve guide until the valve
contacting with valve seat, slightly press down the
valve but do not rotate it so that a seal track will be
created on contact surface.

Contact surface too high

Old valve seat width

60°

1.0mm

Old valve seat width

45°

Caution

The contact surfaces of valve and valve seat are
very important to the valve sealing capacity.

If the contact surface too high, grind the valve seat
with 32° cutter.
Then, grind the valve seat to specified width.

If the contact surface too low, grind the valve seat
with 60° cutter.
Then, grind the valve seat to specified width.

6-12

Contact surface too low

32°

Old valve seat width

60°

To this chapter contents

6. Cylinder Head / Valve

Cylinder Head Disassembly

Remove cam shaft setting plate (1 bolt).

Remove rocker arm shafts and rocker arms.

Special Service Tool:
Rocker arm and cam shaft puller SYM-1445100

Remove cam shafts.

Special Service Tool:
Rocker arm and cam shaft puller SYM-1445100

Use a valve cotter remove & assembly tool to
press the valve spring, and then remove valves.

1 bolt

Cam shaft setting plate

Rocker arm shaft and

cam shaft puller

Cam shafts

Rocker arm

shaft and cam
shaft puller

Caution

y In order to avoid loosing spring elasticity, do not

press the spring too much. Thus, press length
is based on the valve cotter in which can be
removed.

Special Service Tool:
Valve cotter remove & assembly tool
SYM-1471110-SY125

6-6

Valve cotter remove

and assembly tool

To this chapter contents

6. Cylinder Head / Valve

Install camshaft into cylinder head.
Install valve rocker arm, rocker arm shaft and cam
shaft setting plate.

Cylinder Head Installation

Clean up all residues and foreign materials onto
the matching surfaces of both cylinder and
cylinder head.
Install chain guide, dowel pins and a new cylinder
head gasket onto the cylinder.

2 bolts

Cam shaft setting plate

Gasket

Caution

Do not damage the matching surfaces of cylinder
and cylinder head.
Avoid residues of gasket or foreign materials
falling into crankcase as cleaning.

Install 4 washers and tighten 4 nuts on the cylinder
head upper side, and then tighten 2 cylinder head
mounting bolts of cylinder head right side.

Torque value:
Nut 3.6~4.0kgf-m
Bolt 1.0~1.4kgf-m

Install cam chain on to sprocket and align the
timing mark on the sprocket with that of cylinder
head.
Align sprocket bolt hole with camshaft bolt hole.
Tighten the sprocket mounting bolts.

Bolt ×2

Chain guide

Dowel pins

Timing mark

4 nuts

Caution

Make sure timing marks are matched.

6-14

2 bolts

To this chapter contents

Install cylinder head side cover (3 bolts).

Install thermostat (2 bolts).
Loosen auto tensioner adjustment bolt and
remove bolt and spring.
Install tensioner and install spring and adjustment
bolt.

Install cylinder cover (4 bolts).

Install Air Injection system (AI) pipe. (4 bolts)
Install inlet pipe onto cylinder head.
Install and tighten spark plug.

Torque value: 1.0~2.0kgf-m

3 bolts

Tensioner bolts

6. Cylinder Head / Valve

Thermostat bolts

4 bolts

4 bolts

Caution

This model is equipped with more precision
4-valve mechanism so its tighten torque can not
be exceeded standard value in order to avoid
causing cylinder head deformation, engine noise
and leaking so that motorcycle’s performance be
effected.

Install the engine onto frame (refer chapter 5).

6-15

To this chapter contents

6. Cylinder Head / Valve

Valve Clearance Adjustment

Loosen Air Injection system (AI) pipe upper side
bolt (2 bolts).
Remove cylinder head cover.

Remove the cylinder head side cover.

Remove left crankcase cover, and turn the drive
face, and align the timing mark on the cam
sprocket with that of cylinder head, piston is at
TDC position.
Loosen valve clearance adjustment nuts and bolts
located on valve rocker arm.
Measure and adjust valve clearance with feeler
gauge.
After valve clearance had been adjusted to
standard value, hold adjustment bolt and then
tighten the Adjustment nut.

Standard Value: IN 0.10 ± 0.02 mm

EX 0.15 ± 0.02 mm

Install the cylinder head side cover.
Start the engine and make sure that engine oil
flows onto the cylinder head.
Stop the engine after confirmed, and then install
the cylinder head cover and AI pipe.

3 bolts

2 bolts

4 bolts

Timing mark

Caution

y If lubricant does not flow to cylinder head,

engine components will be worn out seriously.
Thus, it must be confirmed.

y When checking lubricant flowing condition, run

the engine in idle speed. Do not accelerate
engine speed.

6-16

Home page

Contents

7. Cylinder / Piston

Mechanism Diagram···························· 7-1
Precautions in Operation ···················· 7-2
Trouble Diagnosis································ 7-2
Cylinder and Piston Removal ············· 7-3

Mechanism Diagram

1.0~1.4kgf-m

Piston Ring Installation ···················7-6
Piston Installation ···························· 7-7
Cylinder Installation························· 7-7

0.8~1.2kgf-m

7

7-1

To this chapter contents

7. Cylinder / Piston

Precautions in Operation

General Information

y Both cylinder and piston service cannot be carried out when engine mounted on frame.

Specification Unit：mm

Item Standard Limit

Cylinder

Piston/
Piston ring

OD of piston pin 16.994~17.000 16.960
Clearance between piston and piston pin 0.002~0.014 0.020
ID of connecting rod small-end 17.016~17.034 17.064

ID 70.995~71.015 71.100
Bend - 0.050

Clearance between piston
rings

Ring-end gap

OD of piston (2nd) 70.430~70.480 70.380
Clearance between piston and cylinder 0.010~0.040 0.100
ID of piston pin boss 17.002~17.008 17.020

Top ring 0.015~0.050 0.090

nd

ring 0.015~0.050 0.090

2
Top ring 0.150~0.300 0.500
2nd ring 0.300~0.450 0.650
Oil ring side rail 0.200~0.700 -

Trouble Diagnosis

Low or Unstable Compression Pressure

y Cylinder or piston ring worn out

Knock or Noise

y Cylinder or piston ring worn out
y Carbon deposits on cylinder head top-side
y Piston pin hole and piston pin wear out

Smoking in Exhaust Pipe

y Piston or piston ring worn out
y Piston ring installation improperly
y Cylinder or piston damage

Engine Overheat

y Carbon deposits on cylinder head top side
y Cooling pipe clogged or not enough in coolant

flow

7-2

To this chapter contents

7. Cylinder / Piston

Cylinder and Piston Removal

Remove cylinder head (refer to chapter 6).
Remove coolant hose from cylinder.
Remove cylinder.

Cover the holes of crankcase and cam chain with
a piece of cloth.
Remove piston pin clip, and then remove piston
pin and piston.

Remove cylinder gasket and dowel pin.
Clean up all residues or foreign materials from
the two matching surfaces of cylinder and
crankcase.

Coolant hose

Caution

y Soap the residues into solvent so that the

residues can be removed more easily.

Inspection

Check if the inner diameter of cylinder is wear out
or damaged.
In the 3 positions, top, center and bottom, of
cylinder, measure the X and Y values respective
in the cylinder.

Service limit: 71.100 mm

Top

Center

Bottom

7-3

To this chapter contents

7. Cylinder / Piston

Check cylinder if warp.

Service limit: 0.05 mm

Measure clearance between piston rings and
grooves.

Service Limit: Top ring: 0.09 mm

nd

2

ring: 0.09 mm

Remove piston rings

Check if the piston rings are damaged or its
grooves are worn.

Caution

Pay attention to remove piston rings because
they are fragile.

Place piston rings respective into cylinder below
20 mm of cylinder top. In order to keep the piston
rings in horizontal level in cylinder, push the rings
with piston.

Service Limit: Top ring: 0.50 mm

nd

ring: 0.65 mm

2

7-4

To this chapter contents

7. Cylinder / Piston

Measure the outer diameter of piston pin.

Service Limit: 16.96 mm

Measure the inner diameter of connecting rod
small end.

Service Limit: 17.064 mm

Measure the inner diameter of piston pin hole.
Service Limit: 17.02 mm
Calculate clearance between piston pin and its
hole.

Service Limit: 0.02 mm

Measure piston outer diameter.

Caution

The measurement position is 10 mm distance
from piston bottom side, and 90° to piston pin.

Service limit：70.380 mm

Compare measured value with service limit to
calculate the clearance between piston and
cylinder.

7-5

To this chapter contents

7. Cylinder / Piston

Piston Ring Installation

Clean up piston top, ring groove, and piston surface.
Install the piston ring onto piston carefully.
Place the openings of piston ring as diagram shown.

Caution

y Do not damage piston and piston rings as installation.
y All marks on the piston rings must be forwarded to up side.
y Make sure that all piston rings can be rotated freely after installed.

Top ring

nd

2

ring

Oil ring

Top groove

nd

2

groove

Oil groove

7-6

To this chapter contents

7. Cylinder / Piston

Piston Installation

Install piston and piston pin, and place the IN
marks on the piston top side forward to inlet
valve.

Install new piston pin clip.

Caution

y Do not let the opening of piston pin clip align

with the piston cutout.

y Place a piece of cloth between piston and

crankcase in order to prevent snap ring from
falling into crankcase as operation.

IN mark

Clip end gap

Cylinder Installation

Clean up all residues and foreign materials on
the matching surface of crankcase. Pay
attention to not let these residues and foreign
materials fall into crankcase.

Caution

Soap the residues into solvent so that the
residues can be removed more easily.

Install dowel pins and new cylinder gasket.

Cutout

Dowel pins

7-7

To this chapter contents

7. Cylinder / Piston

Coat some engine oil to inside of cylinder, piston
and piston rings.
Care to be taken when installing piston into
cylinder. Press piston rings in one by one as
installation.

Caution

Do not push piston into cylinder forcefully
because piston and piston rings will be
damaged.。

Install coolant hose onto cylinder.
Install cylinder head (refer to Chapter 6).

Coolant hose

7-8

Home page

Contents

Mechanism Diagram ··························· 8-1
Maintenance Description···················· 8-2
Trouble Diagnosis······························· 8-2
Left Crankcase Cover ························· 8-3

Mechanism Diagram

8. V-Belt Driving System

Drive Belt··············································8-5
Drive Face·············································8-7
Clutch Outer / Driven Pulley················8-10

8

5.0~6.0kgf-m

8.5~10.5kgf-m

5.0~6.0kgf-m

8-1

To this chapter contents

8. V-Belt Driving System

Maintenance Description

Precautions in Operation
General Information

y Drive face, clutch outer, and driven pulley can be serviced on the motorcycle.
y Drive belt and drive pulley must be free of grease.

Specification

Item Standard value Limit

Driving belt width 24.000 mm 22.500 mm

OD of movable drive face boss 29.946~29.980 mm 29.926 mm

ID of movable drive face 30.000~30.040 mm 30.060 mm

OD of weight roller 19.500~20.000 mm 19.000 mm

ID of clutch outer 144.850~145.150 mm 145.450 mm

Thickness of clutch weight 6.000 mm 3.000 mm

Free length of driven pulley spring 102.400 mm 97.400 mm

OD of driven pulley boss 40.950~40.990 mm 40.930 mm

ID of driven face 41.000~41.050 mm 41.070 mm

Weight of weight roller 17.700~18.300 g 17.200 g

Torque value

y Drive face nut: 8.5~10.5kgf-m
y Clutch outer nut: 5.0~6.0kgf-m
y Drive plate nut: 5.0~6.0kgf-m

Special Service Tools

Clutch spring compressor: SYM-2301000
Inner bearing puller:
Clutch nut wrench 39 x 41 mm:
Universal holder:
Bearing driver:

SYM-6204002

SYM-9020200

SYM-2210100

SYM-9100100

Trouble Diagnosis

Engine can be started but motorcycle can
not be moved

1. Worn drive Belt

2. Worn drive face

3. Worn or damaged clutch weight

4. Broken driven pulley

Shudder or misfire when driving

1. Broken clutch weight

2. Worn clutch weight

Insufficient horsepower or poor high
speed performance

1. Worn drive belt

2. Insufficient spring force of driven pulley

3. Worn roller

4. Driven pulley operation un-smoothly

8-2

To this chapter contents

Left Crankcase Cover

Left crankcase cover removal

Loosen 4 bolts from left side crank out cover &
remove it.
Remove left crankcase cover. (8 bolts)
Remove 2 dowel pin and gasket.

Left crankcase cover install

Install left crankcase cover in the reverse
procedures of removal.

8. V-Belt Driving System

8 bolts

Left cover plate

Bearing setting plate

Drive shaft holder bearing

8-3

To this chapter contents

8. V-Belt Driving System

Left crankcase cover inspection

Remove 2 bolts to remove left crankcase cover
bearing setting plate.

Check bearing on left crankcase cover.
Rotate bearing’s inner ring with fingers.
Check if bearings can be turned in smooth and
silent, and also check if bearing outer ring is
mounted on cover tightly.
If bearing rotation is uneven, noising, or loose
bearing mounted, then replace it.

Bearing replacement

Remove bearing with special service tools

Special tools:
Inner bearing puller SYM-6204022

Install bearing with special service tools.

Special tools:
Right crank case bearing 6201 assembles tool
SYM-9614000-HMA 6201

2 bolts

8-4

To this chapter contents

Drive Belt

Removal

Remove left crankcase cover.
Hold drive face with universal holder, and remove
nut and drive face.

Special Tool：universal holder

Hold clutch outer with universal holder, and
remove nut, bearing stay collar and clutch outer.

Caution

y Using special service tools for tightening or

loosening the nut.

y Fixed rear wheel or rear brake will damage

reduction gear system.

8. V-Belt Driving System

Universal holder

Universal holder

Bearing stay collar

Push the drive belt into belt groove as diagram
shown so that the belt can be loosened, and then
remove the driven pulley.
Remove driven pulley. Do not remove drive belt.
Remove the drive belt from the groove of driven
pulley.

Inspection

Check the drive belt for crack or wear. Replace it
if necessary.
Measure the width of drive belt as diagram shown.

Service Limit: 22.5 mm

Replace the belt if exceeds the service limit.

Belt tooth

Width

Caution

y Using the genuine parts for replacement.
y The surfaces of drive belt or pulley must be

free of grease.

y Clean up all grease or dirt before installation.

8-5