Sym 250i-300i WSM

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10. AC. Generator / Start Clutch 4. Fuel Injection System

AC. Generator Installation 3 screws Data stream (2/3)

Install the AC.G. coil set onto right crankcase
cover (3 screws).
Install pulse generator (2 screws).
Tie the wire harness securely onto the indent of
crankcase.

Caution

Make sure that the wire harness is placed
under pulse generator.

Pulse generator screws

Right Crankcase Cover Installation Dowel pins The screen showed the ECU captured by the engine of the state immediately.

Install dowel pins and new gasket. The following data for the benchmark idling state:
Remove water pump cover.
Install right crankcase cover onto the crankcase. ● BARO------------ kPa (Above 98kPa) →Atmospheric pressure
Note: Align the water pump shaft indent with the oil
pump shaft. ● Intake Air---------- ºC (Outside Temp.) →Intake air temperature

● 2nd AIR VALVE------ V (Idle:ON) →Secondary air solenoid valve actuator state

● INJECT TIME---- mS(Idle:1~3mS) →Injection time

● IGN. ANGLE------------ (Idle:12~14) →Ignition timing

● STEP MOTOR ------ →Idle air control valve step motor actuator state

● CRANKSHAFT ---------- (Idle:CW) →Crankshaft functioning direction

● TEST TERMINAL-- (Idle:OPEN) →Test terminal state

● IDLE SET----------- RPM (=1650 RPM) →Idle speed goal set value

● ISC STEP--------------- (Idle:75~95) →Idle Air Control Valve stepper motor learning step

Install right crankcase cover (10 screws). 10 bolts In the "DATA STREAM" of the screen use "▲" "▼" button to move the left side of the project "→"
Install the dowel pin, new gasket and water pump symbol selected items, press the "ENTER" buttom lock of the project, and press the "F4" button
cover onto crankcase cover. showed that the wave of projects.
Able to use "◄ left" and "right ►" button, can transform View wave numerical size.

Connect coolant hoses onto the right crankcase 4 bolts
cover.
Add engine oil and coolant. 10-9

Numerical analysis of images (2 / 3), the waveform can be displayed as shown in the following items:
BARO
Intaje Air
INJECT TIME
IGN. ANGLE
IDLE SET
ISC STEP

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4. Fuel Injection System 10. AC. Generator / Start Clutch

Data stream (3/3) Flywheel Installation Starting driven gear

Install starting driven gear onto one way clutch.

The screen showed the ECU captured by the engine of the state immediately. Align the key on crankshaft with the flywheel Groove
groove, and then install the flywheel.
The following data for the benchmark idling state:
Hold the flywheel by drive face with universal
● LEARNED STEP--------------- (Set by ECU) →Idle Air Control Valve stepper motor learning holder, and tighten flywheel nut.
Torque value: 5.0~6.0kgf-m
step Special tool:
Universal Holder SYM-2210100
In the "DATA STREAM" of the screen use "▲" "▼" button to move the left side of the project "→"

symbol selected items, press the "ENTER" buttom lock of the project, and press the "F4" button

showed that the wave of projects.

Able to use "◄ left" and "right ►" button, can transform View wave numerical size.

Numerical analysis of images (3 / 3), the waveform can be displayed as shown in the following items:
LEARNED STEP NO.

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10. AC. Generator / Start Clutch 4. Fuel Injection System

Remove the starting gear 3. FREEZED DATA
Loosen 3 starting clutch socket bolts from one way
clutch and remove one way clutch. Objective: When a sensor fault, the EMS system will record all the parameters of fault signals, in
order to facilitate fault diagnosis.
3 bolts
In the directory functions used "▲" "▼" button, select "FREEZED DATA" project, press the "ENTER"
Push out the roller set and check each roller for key to the implementation.
wear or damage.
Only one page, at any screen, press the "EXIT" button, the function can return to the directory screen.
In the "FREEZED DATA" of the screen use "▲" "▼" button to move the left side of the project "→"
symbol selected items, press the "ENTER" buttom lock of the project, and press the "F4" button
showed that the wave of projects.
Able to use "◄ left" and "right ►" button, can transform View wave numerical size.

One way clutch Installation One way clutch
Install the components in the reverse procedures Starting driven gear
of removal.
Torque value: 1.0~1.4kgf-m

Caution

Cannot lock the thread of socket bolt.

Caution

The one way clutch must to with the generator
flywheel and the starter gear, after one and
loads the crank in, only then may lock the
socket bolt, otherwise will create concentric the
deviation, will cause the part to suffer injury.

10-7 4-54

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OD
4. Fuel Injection System 10. AC. Generator / Start Clutch

4. TROUBLE CODE Start Clutch

In the functional directory select "TROUBLE CODE" project, press the "ENTER" button Start Clutch Inspection
implementation, the message began to read fault. Remove start clutch driven gear.
Fault Code: electronic injection system that had happened fault of the message (whether or not Check the gear for wear or damage.
Measure the ID and OD of the start clutch driven
completion of repair). gear.
Without any fault is that showing "System is OK". Service Limit: ID: 25.050 mm
Press the "EXIT" button, the function can return to the directory screen.
OD: 42.100 mm
If the system has faulty code, that is showing the fault code, that can be used "◄ left" and "right ►" or
"▲" "▼" button selected the fault code (selected before the code " " tags) that, press the "ENTER" Check the starting reduction gear and shaft for
button, the code can be read descriptions and fault handling. wear or damage.

Check each roller for wear or damage.

Fault code in the note and treatment of the pages, if the first one page did End, they can press the
"▲" "▼" button to turn the pages to read all that.

Install start clutch driven gear onto one way clutch.
Hold flywheel and rotate start clutch gear.
The start clutch gear should be rotated in C.C.W
direction freely, but not C.W direction. (View as
shown in this figure.)

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10. AC. Generator / Start Clutch 4. Fuel Injection System

Flywheel Removal 5. ERASE TB CODE

Remove right crankcase cover and generator coil. In the directory functions used "▲" "▼" button, select "ERASE TB CODE" project, press the "ENTER"
Remove flywheel nut. key to the implementation.
Conditions: The main switch "ON", or in the engine running state, the fault code can be removed.

Flywheel nut

Installs shaft protector onto the crank shaft.
Special tool:
Shaft protector

Shaft protector Fault code removed, namely showing the "ERASE TB SUCC.!".
Reduction gear Press the "EXIT" button, the function can return to the directory screen.

Remove starter reduction gear and shaft.
Pull out flywheel with AC.G. flywheel puller.
Special tool:
AC.G. Flywheel puller SYM-3110000-HMA

Flywheel puller

Remove flywheel and starting driven gear.

10-5 4-56

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4. Fuel Injection System 10. AC. Generator / Start Clutch

6. CO ADAPTION AC. Generator Removal 3 screws

In the directory functions used "▲" "▼" button, select "CO ADAPTION" project, press the "ENTER" Remove 2 mounting screws from pulse generator.
buttom into the CO adjustment screen. Remove 3 screws from right crankcase cover and
then remove generator coil set.

Pulse generator screws

Right Crankcase Cover Bearing Cir clip

Rotate the bearing with finger to check if the
bearing rotation is in smooth and silent.
Check if the bearing outer parts are closed and
fixed. Replace it if necessary.

Use "◄ left" and "right ►" or "▲" "▼" button, CO value can be adjusted.
CO ADAPT: CO adjusted value.
CO Read: CO read-back value.
Press the "EXIT" button, the function can return to the directory screen.

Remove the bearing 6201with inner bearing puller.
Special tool:
Inner bearing puller SYM-6204022

Inner bearing puller

Install the bearing 6201 bearing with special tool.
Special tool:
Right crankcase cover bearing 6201 presser

SYM-9614000-HMA RB1 6201

Inner bearing presser

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10. AC. Generator / Start Clutch 4. Fuel Injection System

Right Crankcase Cover Removal Troubleshooting Table

Remove left side cover. Test items Comprehensive testing program Parts
Remove seat and luggage box.
(Refer chapter 13) Abnormal Power Fuel Ignition Engine Injection closed- Fault ECU Throttle Engine
Remove the exhaust muffler (3 bolts, 2 nuts). phenomena voltage press. state vacuum state loop position temp.
Code sensor
control Detection sensor
system

3 bolts 2 nuts Start Can’t start
state
Difficult to ˇ
Idle start
Drain out the engine oil and coolant (refer chapter state
5). Without
Remove coolant hoses. idle

Idle not
smooth

RPM NG

CO NG

Coolant hoses Not smooth
Generator couplers Acceler-

ation Inability
and slow

Idle
Flameo- flameout

ut Acceleratio
n flameout

Disconnect the couplers of the power source Related spare parts Roll over Fuel pump Ignition Inlet pipe Injector O2 sensor
output line. sensor coil

Fuel Secondary
air
Power pressure Spark plug Cylinder
relay adjustment head Fuel pump injection
solenoid
Security valve Inlet valve
unit pressure
Fuel pump sensor Fuel
relay pressure
adjustment

valve

Main Fuel filter
switch

Remove water pump cover (4 bolts). 10 bolts Battery
Remove 10 bolts from the right crankcase cover.
Remove the right crankcase cover. Notes: 1. Integrated test motorcycle, according to the "Comprehensive Maintenance list" implementation.
Remove dowel pin and gasket. 2. Spare parts, according to the "EFI System components description" implementation.

4 bolts 4-58

10-3

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4. Fuel Injection System 10. AC. Generator / Start Clutch

Comprehensive Maintenance List Precautions in Operation

No. Maintenance Testing Procedures Test items Determine benchmarks Fault reasons General information
Project Refer to chapter 17: The troubleshooting and inspection of alternator.
Refer to chapter 17: The service procedures and precaution items of starter motor.
1 Power and ●Use meter direct ● Battery voltage ● Battery voltage = 10V Above ● Battery electricity

voltage measurement battery voltage ● Battery connector loose
● Harness circuit opening
●Use diagnosis tool detection ● ECU coupler not connected

of battery voltage properly

2 Fuel ●Use fuel pressure gauge, ● Open the main ● Open main switch, but not ● Fuel not enough Specification Standard value (mm) Limit (mm)
Item 25.026~25.045 25.050
pressure connected in series between switch, but not to start srart: ● Security switch not disarm 42.192~42.208 42.100
ID of starting clutch gear
the injector and the Pressure the engine of pressure = 250kPa (Stable ● Ruel pump relay fault OD of starting clutch gear

Regulating Valve pressure value) ● Ruel pump fault

●Main switch ON, but not ● Pressure in idle ● Idle state: ● Injector fault

start engine ● Rotating throttle, pressure = 294±6kPa ● ECU fault

●Check fuel pressure situation of pressure (Beating situation from top to

●Start engine (idle) changes bottom)

●Check change of the fuel ● rotation throttle moment:

pressure pressure = 294±6kPa (Slightly

●throttle several rotation beating) Torque value
Flywheel nut
●check to the change of fuel Starting clutch hexagon bolt
8 mm bolts
pressure again 12 mm bolts 5.0~6.0kgf-m
1.0~1.4kgf-m with adhesive
3 Ignition state ●The spark plug removed from ● Spark plug ● Specifications: NGK-CR8H ● Spark plug fault Special tools 0.8~1.2kgf-m
AC.G. flywheel puller 1.8~2.2kgf-m
the cylinder head, but the specifications ● Ignition conditions: ● Roll over sensor fault Left crank case cover 6201 bearing puller
Inner bearing puller SYM-3110000-HMA
power lines still ring ● Whether the spark With traditional engines found ● ECU No. 5 pin fault SYM-9614000-HMA RB1 6201
Universal holder SYM-6204022
●Start engines or use for the plug ignition ways ● Ignition coil fault SYM-2210100

diagnosis tool of output View ● Spark plug sparks ● Crankshaft position sensor

spark plug ignition conditions whether it is normal fault

strength

4 Engine ●Diagnosis tool to detect the ● Manifold pressure of ● Manifold pressure ● Valve clearance abnormal
vacuum use of diagnosis tool =32~38kPa ● Intake system leak

5 Injection ● The injector removed from ● Open the main ● Not started, injector not ● Security unit is configured

state the throttle body, but not switch, but did not leaking fuel not disarm

dismantle pipeline start engine the ● In started, the injection state ● Fuel pump relay fault

● Main switch ON, but not injection situation must show fan shape ● Fuel pump fault

start engine ● Injector state when ● Injector fault

● Investigation the injector it’s start ● ECU fault

leaking fuel?

● Once again start engines or

use for the diagnosis tool of

output function

● Check injector fuel injection

and the injection situation

6 Closed - ● Use of diagnostic tool ● Stable condition, ● Idle stable condition: O2 ● O2 Sensor fault
sensor voltage
loop control observation O2 Sensor Sensor voltage = 50 ~ 200mV ● ECU fault
variation (Idle
system voltage changes continued 5 minutes (Show from top to bottom

beating phenomenon)

later to

measurement)

7 Fault Code ● Use of the diagnosis tool ● Diagnosis tool of the ● Without any residual Fault ● throttle position sensor fault
Detection existing fault-detection code fault code is it can be Code ● Engine temperature sensor

or historical Fault Code eliminated ● If residual Fault Code, fault

● Elimination of the ● Start again, the fault according to the "Fault Code ● Intake temperature sensor

implementation of fault is it will happen again Maintenance Form" fault

codes, check can be implementation of ● Manifold pressure sensor

eliminated troubleshooting fault

● Once again start engine ● O2 Sensor fault

● Check fault is it happen ● Crankshaft position sensor

again fault

● ECU fault

● Roll over sensor fault

Notes: 1.Fuel pressure gauge connected between the fuel tank and injector, open the main switch to
repeatedly shut down, fuel system makes pressure stability.

2.Injector and injector cap tightly by hands, fuel spills should not be the case.

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10. AC. Generator / Start Clutch 4. Fuel Injection System

Mechanism Diagram···························10-1 Flywheel Removal ······························10-5 Note:
Precautions in Operation ···················10-2 Start Clutch ·········································10-6
Right Crankcase Cover Removal ······10-3 Flywheel Installation ··························10-8
AC. Generator Removal······················10-4 AC.Generator Installation ··················10-9
Right Crankcase Cover Bearing ········10-4 Right Crankcase Cover Installation ··10-9

Mechanism Diagram

0.8~1.2kgf-m

1.0~1.4kgf-m
5.0~6.0kgf-m

10-1 4-60

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5. Removal & Installation of Engine 9. Final Drive Mechanism

Precautions in Operation···················· 5-1 Rear Fork ·············································· 5-9 Final Drive Mechanism Reassembly Clutch nut wrench Drive shaft and
Engine Removal ·································· 5-2 Engine Bush Removal ························· 5-11 seal install socket
Engine Hanger ····································· 5-8 Engine Installation ······························· 5-12 Install drive shaft.
Special tool:
Precautions in Operation Drive shaft puller SYM-2341110- HMA RB1
Drive shaft socket & oil seal driver (25*40*8)
General Information
SYM-9120200-HMA
Engine must be supported by a bracket or adjustable tool in height. Clutch nut wrench SYM-9020200
The following parts can be serviced with the engine installed on the frame.
Drive shaft puller
1. Carburetor.
2. Driving disk, driving belt, clutch, and transporting disk.
3. Final reduction gear mechanism.
4. AC. Generator.

Specification Apply with grease onto drive shaft oil seal.
Install the oil seal to left crankcase.
Item LM25W5-6/7/P Special tool:
LM25W7-7 Drive shaft socket & oil seal driver (25*40*8)
LM30W-6/T SYM-9120200-HMA

Engine Oil Capacity Replacement 1,200 c.c.
Disassemble
1,400 c.c.

Gear Oil Capacity Replacement 160 c.c. Oil seal driver
Disassemble 180 c.c. Dowel pins

Capacity of coolant Engine + radiator 850 c.c. Install 2 dowel pins & new gasket.
Reservoir upper 420 c.c.

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

Install counter shaft and final shaft into the gear Final shaft Drive shaft
box cover. Counter shaft
Install the gear box and tighten the bolts (7 bolts).
5-1 Torque value: 2.6~3.0kgf-m
Install driven pulley / clutch outer / belt.
Install movable drive face, drive face and left
crankcase cover.
Install rear wheel.
Add gear oil.
Gear oil quantity: 180c.c.

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9. Final Drive Mechanism 5. Removal & Installation of Engine

Install new final shaft bearing and bearing puller Engine Removal
onto left crankcase.
Special tool: Open inner box cover.
Bearing puller 6205 SYM-9100400-6205 Remove battery cover (1 screw).
Remove the battery negative (-) cable.
Install assembly directs puller bearing puller. Remove the battery positive (+) cable.
Special Service Tools:
Assembly directs puller SYM-2341110 Assembly
directs puller

Bearing puller 6205 Positive Negative

Use screw driver holder bearing puller lower part, Assembly Open the seat.
and turn the bearing puller upper part to install the directs puller Remove the luggage box (6 bolts, 2 screws).
final shaft bearing. (Refer to chapter 14)

Apply with grease onto final shaft oil seal. Remove right and left side covers (4 screws on
Install the oil seal into gear box cover. each side.).
Special tool: Remove rear carrier (4 bolts).
Oil seal driver 34*52*5 SYM-9125500-HMA Remove body cover (4 screws & 1 coupler).
(Refer to chapter 14)

Oil seal driver Remove fuel injection system of electrical Idle speed control valve

9-7 couplers and fuel hoes
Remove idle speed control valve, inlet pressure

sensor, nozzle of couplers.

inlet pressure sensor coupler Nozzle coupler

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5. Removal & Installation of Engine 9. Final Drive Mechanism

Remove the temperature meter sensor and engine Temperature meter Engine temperature Install assembly directs puller bearing puller.
temperature sensor wire couplers. sensor sensor Special Service Tools:
Assembly directs puller SYM-2341110
Remove throttle position sensor coupler. Throttle position sensor Use screw driver hold bearing puller lower part, Assembly directs puller
and turn the bearing puller upper part to install the Inner bearing puller
drive shaft bearing.
Remove inlet temperature sensor coupler. Inlet temperature sensor
Gear box cover side
Remove drive shaft bearing and counter shaft
bearing from gear box cover using following tools.
Special tool:
Inner bearing puller SYM-6204020 or
SYM-6204021

Remove oil seal, and then remove final shaft
bearing from gear box cover using following tools.
Special tool:
Inner bearing puller SYM-6204022

Inner bearing puller

Remove secondary air electromagnetic valve pipe. Secondary air pipe Install a new drive shaft bearing and counter shaft
bearing into gear box cover.

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9. Final Drive Mechanism 5. Removal & Installation of Engine

Bearing Replacement Outer bearing puller Remove AC. generator and crankshaft position sensor AC. generator and crankshaft
coupler. position sensor coupler
Left crankcase side Remove start motor wire from the start relay.

If the drive shaft is pulled out with its bearing, then

remove the bearing with bearing puller and shaft

protector.

Special tool:

Multi-functional bearing puller or Outer bearing

puller SYM-6204001

Shaft protector SYM-6204010

Remove final shaft bearing and counter shaft Remove O2 sensor wire coupler. Start motor wire
bearing from left crankcase using following tools. O2 sensor coupler
Special tool:
Inner bearing puller SYM-6204020 or
SYM-6204021

Caution Inner bearing Remove fuel pump relay wire coupler. O2 sensor coupler
Never install used bearings. Once bearing puller
removed, it has to be replaced with new one. Start engine for the pipeline to be exhausted within the Fuel pump relay coupler
Install new final shaft bearing and counter shaft Bearing driver residual pressure, the engine flameout, relaxing fuel Fuel tube
bearing into left crankcase. tube folder, open for fuel tube.
Special tool:
Bearing driver 6205 SYM-9615000-6205 Caution
Bearing driver HK1516 SYM-9100200-HK1516
● Demolition for the pipeline, will be required for
Install new drive shaft bearing and bearing puller residual pressure in the pipeline to divest, or use
onto left crankcase. the folder surrounds the tubing to prevent petrol
Special tool: splash.
Bearing puller 6205 SYM-9100400-6205
5-4
Bearing puller 6205

9-5

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5. Removal & Installation of Engine 9. Final Drive Mechanism

Carburetor type and other common Auto by-starter coupler Final Drive Mechanism Inspection

Mechanical Check if the drive shaft in burned, worn or
Remove the power coupler of auto by-starter. damaged and replace it if necessary.
Remove the spark plug cap.
Caution
Remove the generator power wire and pulse Spark plug cap If remove the drive shaft from the gear box
generator connector. upper side, then its bearing has to be
Remove the starter motor wire. Couplers of the generator and replaced.
pulse generator
Check if the countershaft is wear or damage and
replace it if necessary.

Starter motor wire

Remove engine blow-by pipe. Check if the final shaft and gear are burn, wear or
damage and replace it if necessary.

Engine blow-by pipe

Remove the fuel line, vacuum hose, and throttle Check bearings on gear box cover. Oil seal Bearing
valve cable from the carburetor. Rotate each bearing’s inner ring with fingers.
Loosen the clamp strip of air cleaner and Check if bearings can be turned in smooth and
carburetor, and then remove the air cleaner hose. silent, and also check if bearing outer ring is
mounted on gear tightly.
Clamp strip If bearing rotation is uneven, noising, or loose
bearing mounted, then replace it.
5-5 Check oil seal for wear or damage, and replace it
if necessary.
Check gear box bearing as the same way above,
and replace it if necessary.

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9. Final Drive Mechanism 5. Removal & Installation of Engine

Final Drive Mechanism Disassembly Remove the air cleaner inlet pipe connection bolt 1 Bolt
(1 bolt).
Remove the rear wheel.
Remove the clutch.
Drain out gear oil from gear box.
Loosen 7 bolts and remove gear box cover bolts.

7 bolts

Remove the gear box cover. Remove the air cleaner connection bolts (2 bolts).
Remove the gasket & dowel pin. Remove the air cleaner.

2 bolts

Remove final gear. Remove the exhaust muffler (3 bolts, 2 nuts).
Remove counter shaft, gear and 2 washers.
Remove final shaft.

Final shaft Counter shaft 3 bolts 2 nuts

Remove the drive shaft. Drain out coolant, and remove coolant inlet hose.
Special tool:
Shaft protector

Caution

If non- essential do not remove the drive shaft
from the cover upper side.
If remove the drive shaft from the gear box
cover, then its bearing has to be replaced.

Drive shaft Drain bolt Inlet hose

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5. Removal & Installation of Engine 9. Final Drive Mechanism

Remove the coolant outlet hose and Outlet hose Precautions in Operation
thermo-sensor wire.
Specification
Application oil: scooter gear oil
Recommended oil: KING MATE serial gear oils
Oil quantity: 180 c.c. (160 c.c. when replace)

Torque value
Gear box cover 2.6~3.0kgf-m

Thermo-sensor wire Special tools

Remove rear brake hose clamp and rear brake Bearing (6205) driver SYM-9615000-6205
caliper. Bearing (6205) puller
Bearing (6203) driver SYM-9100400 HMA RA1 6205
Drive shaft & oil seal (25*40*8) socket
Bearing (HK1516) driver SYM-9620000
Bearing (6204) driver
Oil seal drive 34*52*5 SYM-9120200-HMA
Inner bearing puller
Outer bearing puller SYM-9100200-HMA HK1516
Drive shaft install puller
Bearing install puller SYM-9110400-6204
Clutch nut wrench SYM-9125500-HMA
SYM-6204021 or SYM-6204022
SYM-6204001
SYM-2341110- HMA RB1
SYM-2341100
SYM-9020200

Remove the right rear cushion lower bolt (1 bolt). 2 bolts Brake hose clamp
Remove the rear fork bolts (2 bolts). Rear axle nut 2 bolts
Remove the rear wheel axle nut (1 nut).
Troubleshooting
1 bolt
Engine can be started but motorcycle can not be moved.
Remove the rear fork and rear axle collars. Damaged driving gear
Burnt out driving gear
Damaged driving belt.

Noise
Worn or burnt gear
Worn gear

Gear oil leaks
Excessive gear oil.
Worn or damage oil seal

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9. Final Drive Mechanism 5. Removal & Installation of Engine

Mechanism Diagram······························ 9-1 Final Drive Mechanism Inspection ······· 9-4 Remove left rear cushion lower bolt (1 bolt).
Precautions in Operation ······················ 9-2 Bearing Replacement ···························· 9-5
Troubleshooting ···································· 9-2 Final Drive Mechanism Reassembly ···· 9-8
Final Drive Mechanism Disassembly ··· 9-3

Mechanism Diagram

1 bolt

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

Final shaft

Final gear Engine side bolt

Counter gear Engine Hanger
Drive shaft
Removal
Counter shaft 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

9-1 5-8

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5. Removal & Installation of Engine 8. V-Belt Drive System

Rear Fork Cir clip Installation of Clutch Outer/Driven Pulley Oil seal
Assembly
Bearing Inspection Install new oil seal and O-ring onto movable driven
face.
Check bearings on rear fork. Apply with specified grease to lubricate the inside
Rotate bearing inner ring with fingers. of movable driven face.
Check if bearing can be turned in smooth and
silent, and also check if bearing outer ring is Specified grease
mounted on rear fork tightly.
If bearing rotation is uneven, noising, or loose
bearing mounted, then replace it.

O-ring

Install the movable driven face onto driven face. Movable driven face Guide pin
Install the guide pin and guide pin roller.
Bearing removal Oil seal

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

O-ring Guide pin Guide pin roller
Collar
Bearing installation Install the collar.
Install new rear axle bearing and baring puller into
rear fork. 6303 bearing puller
Special Service Tools:
Rear fork bearing puller SYM-6303000-6303 Install friction plate, spring and clutch weight into
clutch spring compressor, and press down the
Install the washer of the 6303 bearing puller. assembly by turning manual lever until mounting
nut that can be installed.
6303 bearing puller washer Hold the compressor by bench vise and tighten Clutch nut wrench
the mounting nut to specified torque with clutch Clutch spring compressor
nut wrench.
5-9 Remove the clutch spring compressor.
Torque value: 5.0~6.0kgf-m
Install clutch outer/driven pulley and drive belt onto
drive shaft.

8-14

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8. V-Belt Drive System 5. Removal & Installation of Engine

Install snap ring and mounting plate onto setting Install assembly directs puller bearing puller.
pin. Special Service Tools:
Assembly directs puller SYM-2341110

Snap ring Bearing puller
Clipper
Replacement of Driven Pulley Bearing Outer bearing Use screw driver holder bearing puller lower part, and
Remove inner bearing. turn the bearing puller upper part to install the rear fork
bearing.
Caution
If the inner bearing equipped with oil seal on Inner needle
side in the driven pulley, then remove the oil bearing
seal firstly.
If the pulley equipped with ball bearing, it has to Snap ring
remove snap ring and then the bearing.
Install bearing mounting cir clip. Cir clip
Remove snap ring and then push bearing forward
to other side of inner bearing. Snap ring
Place new bearing onto proper position and its Outer bearing
sealing end should be forwarded to outside. Bearing end
Apply with specified oil.
Inner bearing
Install new inner bearing.
Caution

Its sealing end should be forwarded to outside
as bearing installation.
Install needle bearing with hydraulic presser.
Install ball bearing by means of hydraulic
presser.
Install snap ring into the groove of drive face.
Align oil seal lip with bearing, and then install the
new oil seal (if necessary).

8-13 5-10

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5. Removal & Installation of Engine 8. V-Belt Drive System

Engine Bush Removal Clutch weight Replacement Spring Driving plate
Remove snap ring and washer, and then remove
If the engine hanger frame and the cushion rubber clutch weight and spring from driving plate. Snap ring
of rear cushion bush is damaged. With the bush Setting pin
remover / presser, ø28mm & ø20mm, to press the Caution
bush out, and replace it with new one.
Some of models are equipped with one
Engine hanger bush: ø 28mm mounting plate instead of 3 snap rings.
Rear cushion bush: ø 20mm
Check if spring is damage or insufficient elasticity.
Pressing out
Place the detent section of the bush remover Check if shock absorption rubber is damage or Clutch weight
toward the bush, and drive both the pressing ring deformation. Replace it if necessary. Shock absorption rubber
and bolt in to press the bush out. Apply with grease onto setting pins.
Special Service Tools:
Crankcase bush remover/presser SYM-1120310
Crankcase bush remover/presser SYM-1120320

Pressing In Install new clutch weight onto setting pin and then Shock absorption rubber
push to the specified location.
Place the flat section of the remover toward the Apply with grease onto setting pins. Clutch weight
bush, and then drive the bush, pressing ring, and But, the clutch block should not be greased. If so, Spring
bolt in to install the bush. replace it.

Caution
Grease or lubricant will damage the clutch
weight and affect the block’s connection
capacity.

Install the spring into groove with pliers.

5-11 8-12

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8. V-Belt Drive System 5. Removal & Installation of Engine

Clutch weight Replace Engine Installation
Measure each clutch weight thickness.
it if exceeds service limit. Install the engine according to the reversing order
Service limit: 3.0 mm of removal.

Clutch weight Caution
Note both feet and hands safety for
Driven pulley spring squeezing as engine installation.
Measure the length of driven pulley spring. Do not bent or squeeze each wires or hose.
Replace it if exceeds service limit. Route all cables and wires in accordance with
Service limit: 97.400 mm the routine layout.
Engine hanger nut:
Free length Torque Value: 7.5~9.5kgf-m
Rear cushion bolt:
Driven pulley Driven face Torque Value: upper: 3.5~4.5kgf-m
Check following items: Movable driven face
under: 2.4~3.0kgf-m
If both surfaces are damaged or worn. Rear wheel axle nut:
If guide pin groove is damaged or worn. Torque Value: 11.0~13.0kgf-m
Replace damaged or worn components.
Measure the outer diameter of driven face and the 5-12
inner diameter of movable driven face. Replace it
if exceeds service limit.
Service limit: Outer diameter 40.93 mm

Inner diameter 41.07 mm

Driven Pulley Bearing Inspection Guide pin groove
Check if the inner bearing oil seal is damage. Needle bearing
Replace it if necessary.
Check if needle bearing is damage or too big
clearance. Replace it if necessary.
Rotate the inside of inner bearing with fingers to
check if the bearing rotation is in smooth and silent.
Check if the bearing outer parts are closed and
fixed. Replace it if necessary.

Outer ball bearing

8-11

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6. Cylinder Head / Valve 8. V-Belt Drive System

Mechanism Diagram··························· 6-1 Valve Stem Replacement ··················· 6-10 Clutch Outer / Driven Pulley Clutch nut wrench
Precautions in Operation ··················· 6-2 Valve Seat Inspection and Service ···· 6-11 Clutch spring compressor
Troubleshooting ································· 6-3 Cylinder Head Reassembly ················ 6-13 Disassembly
Cylinder Head Removal······················ 6-4 Cylinder Head Installation ·················· 6-14 Remove drive belt, clutch outer and driven pulley.
Cylinder Head Disassembly··············· 6-6 Valve Clearance Adjustment·············· 6-16 Install clutch spring compressor onto the pulley
Cylinder Head Inspection··················· 6-8 assembly, and operate the compressor to let the
wrench be installed more easily.
Mechanism Diagram
Caution
1.0~1.4kgf-m 1.0~1.4kgf-m 1.0~1.4kgf-m
1.0~1.2kgf-m Do not press the compressor too much.
1.0~1.4kgf-m
Hold the clutch spring compressor onto bench vise,
and then remove mounting nut with special service
tool.
Release the clutch spring compressor and remove
friction plate, clutch weight and spring from driven
pulley.

Remove seal collar from driven pulley.

0.7~1.1kgf-m Movable driven face Collar
Guide pin
Remove guide pin, guide pin roller, and movable Seal
driven face, and then remove O-ring & oil seal
seat from movable driven face.

3.6~4.0kgf-m

2.4~3.0kgf-m

1.0~1.4kgf-m 1.0~1.2kgf-m

Inspection O-ring Guide pin Guide pin roller
Clutch outer Clutch outer
Measure the inner diameter of clutch outer. Inner
Replace the clutch outer if exceed service limit. diameter
Service limit: 145.450 mm

1.0~1.4kgf-m

6-1 8-10

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8. V-Belt Drive System 6. Cylinder Head / Valve

With 4~5g grease spreads wipes drives in the Precautions in Operation
movable drive face axis hole.
Install drive face boss. General Information
This chapter is contained maintenance and service for cylinder head, valve, and camshaft as well as
Caution rocker arm.
The movable drive face surface has to be free Cylinder head service can be carried out when engine is in frame.
of grease. Clean it with cleaning solvent.

Specification

Item Standard Limit
12±2 kg/cm2 ---
Compression pressure
34.880 34.860
Drive face boss Camshaft Height of cam lobe Intake 34.740 34.725
Drive face boss Exhaust 11.982~12.000 12.080
11.966~11.984 11.936
Install movable drive face comp. onto crankshaft. Movable drive face ID of valve rocker arm 4.975~4.990 4.900
OD of valve rocker arm shaft 4.950~4.975 4.900
Rocker arm 5.000~5.012 5.030
0.010~0.037 0.080
OD of valve stem Intake 0.025~0.062 0.100
Exhaust 38.700 35.200
40.400 36.900
ID of valve guide 1.600
0.10±0.02mm ---
Crank shaft Valve Clearance between Intake 0.15±0.02mm ---
Press down valve stem and guide Exhaust ---
Inner --- 0.050
Free length of valve outer
spring

Driven pulley installation Valve seat width
Press drive belt into pulley groove, and then pull
the belt onto drive shaft. Valve clearance Intake
Exhaust

Tilt angle of cylinder head

Drive belt Torque Value 1.0~1.4kgf-m
Cylinder head cover bolt 2.4~3.0kgf-m
Install drive face, washer and nut. Exhaust pipe stud bolt 1.0~1.4kgf-m
Cylinder head bolt 3.6~4.0kgf-m
Caution Cylinder head Nut 0.8~1.2kgf-m
Sealing bolt of cam chain auto-tensioner 1.2~1.6kgf-m
Make sure that two sides of pulley surfaces Bolt of cam chain auto-tensioner 1.0~1.4kgf-m
have to be free of grease. Clean it with Cylinder side cover bolt 1.0~1.4kgf-m
cleaning solvent. Cam sprocket bolt 0.7~1.1kgf-m
Tappet adjustment screw nut 1.0~1.2kgf-m
Hold drives face with universal holder. Spark plug
Tighten nut to specified torque.
Torque value: 8.5~10.5kgf-m Tools
Install left crankcase cover. Special service tools
Valve reamer: 5.0mm
Valve guide driver: 5.0mm
Valve spring compressor

8-9 6-2

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6. Cylinder Head / Valve 8. V-Belt Drive System

Troubleshooting Inspection Weight roller
The weight rollers are to press movable drive face
Engine performance will be affected by troubles on engine top parts. The trouble usually can be by means of centrifuge force.
determined or by performing cylinder compression test and judging the abnormal noise generated. Thus, if weight rollers are worn out or damaged,
the centrifuge force will be affected.
Low compression pressure Check if rollers are worn or damaged. Replace it
1. Valve if necessary.
Measure each roller’s outer diameter. Replace it if
Improper valve adjustment exceed the service limit.
Burnt or bent valve Service limit: 19.0 mm
Improper valve timing Weight: 17.2g
Valve spring damage
Valve carbon deposit. Check if drive face boss is worn or damaged and Movable drive face
2. Cylinder head Drive face boss
Cylinder head gasket leaking or damage replace it if necessary.
Tilt or crack cylinder Closure surface
Measure the outer diameter of movable drive face
3. Piston
Piston ring worn out. boss, and replace it if it exceed service limit.
Service limit: 29.962 mm
High compression pressure
Too much carbon deposit on combustion chamber or piston head Measure the inner diameter of movable drive face,

Noise and replace it if it exceed service limit.
Improper valve clearance adjustment Service limit: 30.060 mm
Burnt valve or damaged valve spring
Camshaft wear out or damage Reassembly/installation Weight roller
Chain wear out or looseness Install weight rollers.
Auto-tensioner wear out or damage
Camshaft sprocket Caution
Rocker arm or rocker arm shaft wear out
The weight roller two end surfaces are not
certainly same. In order to lengthen the roller
life and prevented exceptionally wears the
occurrence, Please end surface of the closure
surface counter clockwise assembles onto
movable drive face.

Install ramp plate. Ramp plate

Guide collar

6-3 8-8

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8. V-Belt Drive System 6. Cylinder Head / Valve

Drive Face Universal holder Cylinder Head Removal

Removal Remove engine. (Refer to chapter 5)
Remove left crankcase cover.
Hold drive face with universal holder, and then
remove drive face nut.
Remove drive face and drive belt.

Remove movable drive face comp and drive face Movable drive face Remove 2 bolts of thermostat and then remove Tensioner bolts
boss from crankshaft. the thermostat.
Remove hole bolt and spring for the cam chain
tensioner.
Loosen 2 bolts, and then remove tensioner.
Remove thermostat (2 bolts).

Crankshaft Drive face boss Thermostat bolts
Ramp plate 4 bolts
Remove ramp plate. Remove Air Injection system (AI) pipe mounting
bolts.
Remove spark plug.

Remove weight rollers from movable drive face. Movable drive face Remove cylinder head cover (4 bolts). 4 bolts

Weight roller 8-7 6-4

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6. Cylinder Head / Valve 8. V-Belt Drive System

Remove the side cover mounting blots of cylinder 3 bolts Installation
head, and then take out the side cover. Caution

Pull out driven face to avoid it closing. Driven face
Cannot oppress friction plate comp in order to
Remove left crankcase cover, and turn the Timing mark avoid creates the distortion or the damage.
Turn the drive face, and align the timing mark on 2 bolts Install drive belt onto driven pulley.
the sprocket with that of cylinder head, piston is at
TDC position. Install the driven pulley that has installed the belt
Remove cam sprocket bolts and then remove the onto drive shaft.
sprocket by prying chain out. On the drive belt another end to the movable drive
face.

Remove the 2 cylinder head mounting bolts from Bolt ×2 Universal holder Bearing stay collar
cylinder head right side, and then remove 4 nuts
and washers from cylinder head upper side. Install the clutch outer and bearing stay collar.
Remove the cylinder head. Hold the clutch outer whit universal holder, and
then tighten nut to specified torque value.
Torque value: 5.0~6.0kgf-m

4 nuts

Remove cylinder head gasket and 2 dowel pins. 2 dowel pins Universal holder
Remove chain guide.
Clean up residues from the matching surfaces of Install the drive face, washer and drive face nut.
cylinder and cylinder head. Hold drive face with universal holder, and then
tighten nut to specified torque value.
Caution Torque value: 8.5~10.5kgf-m

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

Cam chain guide 8-6

6-5

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8. V-Belt Drive System 6. Cylinder Head / Valve

Drive Belt Universal holder Cylinder Head Disassembly 1 bolt Cam shaft setting plate

Removal Remove cam shaft setting plate (1 bolt).
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 Universal holder Bearing stay collar Remove rocker arm shafts and rocker arms.
remove nut, bearing stay collar and clutch outer. Special Service Tool:
Rocker arm and cam shaft puller SYM-1445100
Caution

Using special service tools for tightening or
loosening the nut.
Fixed rear wheel or rear brake will damage
reduction gear system.

Push the drive belt into belt groove as diagram Remove cam shafts. Rocker arm shaft and
shown so that the belt can be loosened, and then Special Service Tool: cam shaft puller
remove the driven pulley. Rocker arm and cam shaft puller SYM-1445100
Remove driven pulley. Do not remove drive belt. Cam shafts
Remove the drive belt from the groove of driven
pulley.

Inspection Belt tooth Use a valve cotter remove & assembly tool to Rocker arm
Check the drive belt for crack or wear. Replace it press the valve spring, and then remove valves. shaft and cam
if necessary. Width shaft puller
Measure the width of drive belt as diagram shown. Caution
Service Limit: 22.5 mm 8-5 In order to avoid loosing spring elasticity, do not Valve cotter remove
Replace the belt if exceeds the service limit. press the spring too much. Thus, press length and assembly tool
is based on the valve cotter in which can be
Caution removed.
Special Service Tool:
Using the genuine parts for replacement. Valve cotter remove & assembly tool
The surfaces of drive belt or pulley must be SYM-1471110-SY125
free of grease.
Clean up all grease or dirt before installation. 6-6

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6. Cylinder Head / Valve 8. V-Belt Drive System

Remove valve cotters, spring retainers, springs Inlet valve Inner spring Spring retainer Left crankcase cover inspection 2 bolts
and valves. Remove 2 bolts to remove left crankcase cover
bearing setting plate.

Exhaust valve Outer spring Cotter

Remove valve stem seals. Check bearing on left crankcase cover.
Rotate bearing’s inner ring with fingers.
Valve stem seals Check if bearings can be turned in smooth and
silent, and also check if bearing outer ring is
Clean carbon deposits in combustion chamber. mounted on cover tightly.
Clean residues and foreign materials on cylinder If bearing rotation is uneven, noising, or loose
head matching surface. bearing mounted, then replace it.

Caution Bearing replacement
Do not damage the matching surface of Remove bearing with special service tools
cylinder head. 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

6-7 8-4

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8. V-Belt Drive System 6. Cylinder Head / Valve

Left Crankcase Cover Cylinder Head Inspection

Left crankcase cover removal Check if spark plug and valve holes are cracked.
Loosen 4 bolts from left side crank out cover & Measure cylinder head warp with a straightedge
remove it. and thickness gauge.
Remove left crankcase cover. (8 bolts) Service limit: 0.05 mm
Remove 2 dowel pin and gasket.
Camshaft
Left crankcase cover install 8 bolts Inspect cam lobe height for damaged.
Install left crankcase cover in the reverse Service Limit:
procedures of removal.
IN: Replacement when less than 34.860mm
Bearing setting plate EX: Replacement when less than 34.725mm
Drive shaft holder bearing Inspect the camshaft bearing for looseness or
wear out. If any damage, replace whole set of
Left cover plate camshaft and bearing.

8-3 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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6. Cylinder Head / Valve 8. V-Belt Drive System

Valve spring free length Precautions in Operation
Measure the free length of intake and exhaust
valve springs. General Information
Service limit: Drive face, clutch outer, and driven pulley can be serviced on the motorcycle.
Inner spring 35.20 mm Drive belt and drive pulley must be free of grease.
Outer spring 36.90 mm
Specification
Valve stem Item Standard value Limit
Check if valve stems are bend, crack or burn. Drive belt width 24.000 mm 22.500 mm
Check the operation condition of valve stem in OD of movable drive face boss 29.926 mm
valve guide, and measure & record the valve stem ID of movable drive face 29.946~29.980 mm 30.060 mm
outer diameter. OD of weight roller 30.000~30.040 mm 19.000 mm
Service Limit: IN: 4.90 mm ID of clutch outer 19.500~20.000 mm
Thickness of clutch weight 144.850~145.150 mm 145.450 mm
EX: 4.90 mm Free length of driven pulley spring 3.000 mm
Valve guide OD of driven pulley boss 6.000 mm
ID of driven face 102.400 mm 97.400 mm
Caution Weight of weight roller 40.950~40.990 mm 40.930 mm
41.000~41.050 mm 41.070 mm
Before measuring the valve guide, clean 17.700~18.300 g 17.200 g
carbon deposits with reamer.
Torque value Special Service Tools
Tool: 5.0 mm valve guide reamer Drive face nut: 8.5~10.5kgf-m Clutch spring compressor: SYM-2301000
Clutch outer nut: 5.0~6.0kgf-m Inner bearing puller: SYM-6204002
Measure and record each valve guide inner Drive plate nut: 5.0~6.0kgf-m Clutch nut wrench 39 x 41 mm: SYM-9020200
diameters. Universal holder: SYM-2210100
Service limit: 5.03 mm Bearing driver: SYM-9100100
The difference that the inner diameter of valve
guide deducts the outer diameter of valve stem is 5.0 mm valve guide reamer Troubleshooting Insufficient horsepower or poor high
the clearance between the valve stem and valve speed performance
guide. 6-9 Engine can be started but motorcycle can 1. Worn drive belt
Service Limit: IN 0.08 mm not be moved 2. Insufficient spring force of driven pulley
1. Worn drive Belt 3. Worn roller
EX 0.10 mm 2. Worn drive face 4. Driven pulley operation un-smoothly
3. Worn or damaged clutch weight
Caution 4. Broken driven pulley

If clearance between valve stem and valve Shudder or misfire when driving
guide exceeded service limit, check whether 1. Broken clutch weight
the new clearance that only replaces new valve 2. Worn clutch weight
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.

Caution

It has to correct valve seat when replacing
valve guide.

8-2

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8. V-Belt Drive System 6. Cylinder Head / Valve

Mechanism Diagram····························8-1 Drive Belt ············································· 8-5 Valve Stem Replacement Valve guide driver
Precautions in Operation ····················8-2 Drive Face ············································ 8-7 5.0mm
Troubleshooting ··································8-2 Clutch Outer / Driven Pulley ··············· 8-10 Heat up cylinder head to 100~150 ℃ with heated
Left Crankcase Cover··························8-3 plate or toaster.

Mechanism Diagram Caution

Do not let torch heat cylinder head directly.
Otherwise, the cylinder head may be deformed
as heating it.
Wear on a pair of glove to protect your hands
when operating.

5.0~6.0kgf-m Hold the cylinder head, and then press out old Valve guide driver
5.0~6.0kgf-m valve guide from combustion chamber side. 5.0 mm

Tool: Valve guide driver: 5.0 mm Valve guide reamer 5.0 mm

8.5~10.5kgf-m Caution

Check if new valve guide is deformation after
pressed it in.
When pressing in the new valve guide, cylinder
head still have to be kept in 100~150℃.

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

Using cutting oil when correcting valve guide
with a reamer.
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

8-1 6-10

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6. Cylinder Head / Valve 7. Cylinder / Piston

Valve Seat Inspection and Service Coat some engine oil to inside of cylinder, piston
and piston rings.
Clean up all carbon deposits onto intake and Care to be taken when installing piston into
exhaust valves. cylinder. Press piston rings in one by one as
Apply with emery slightly onto valve contact face. installation.
Grind valve seat with a rubber hose or other
manual grinding tool. Caution

Caution Do not push piston into cylinder forcefully
Do not let emery enter into between valve stem because piston and piston rings will be
and valve guide. damaged.
Clean up the emery after corrected, and apply
with engine oil onto contact faces of valve and Install coolant hose onto cylinder.
valve seat. Install cylinder head (refer to Chapter 6).
Remove the valve and check its contact face.
Valve seat width Coolant hose
Caution
Replace the valve with new one if valve seal is Roughness
roughness, wear out, or incomplete contacted 45°
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.

Old valve seat width

32° 7-8

6-11

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Piston Installation IN mark 6. Cylinder Head / Valve

Install piston and piston pin, and place the IN Use 60° cutter to cut a quarter lower parts out.
marks on the piston top side forward to inlet valve. Remove the cutter and check new valve seat.

Old valve seat width

Install new piston pin clip. Clip end gap Use 45° cutter to grind the valve seat to specified 60°
Caution Cutout width. 1.0mm
Do not let the opening of piston pin clip align
with the piston cutout. Caution
Place a piece of cloth between piston and Make sure that all roughness and uneven faces
crankcase in order to prevent snap ring from had been ground.
falling into crankcase as operation.
Grind valve seat again if necessary.
Cylinder Installation
Coat the valve seat surface with red paint. Contact surface too high 45°
Clean up all residues and foreign materials on the Install the valve through valve guide until the valve
matching surface of crankcase. Pay attention to contacting with valve seat, slightly press down the Old valve seat width
not let these residues and foreign materials fall valve but do not rotate it so that a seal track will be 32°
into crankcase. created on contact surface.

Caution Caution
Soap the residues into solvent so that the
residues can be removed more easily. The contact surfaces of valve and valve seat
are very important to the valve sealing capacity.
Install dowel pins and new cylinder gasket.
If the contact surface too high, grind the valve seat
with 32° cutter. Contact surface too low Old valve seat width
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.

60°

Dowel pins

7-7 6-12

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6. Cylinder Head / Valve 7. Cylinder / Piston

After the valve seat ground, coat valve seat Piston Ring Installation
surface with emery and then slightly press the
ground surface. Clean up piston top, ring groove, and piston surface.
Clean up all emery coated onto cylinder and valve Install the piston ring onto piston carefully.
after ground. Place the openings of piston ring as diagram shown.

Caution

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

Cylinder Head Reassembly Valve spring retainer Valve stem seal
Valve cotter Inlet valve
Lubricate valve stem with engine oil, and then
insert the valve into valve guide. Valve spring Top ring
Install new valve stem oil seal. Exhaust valve 2nd ring
Install valve springs and retainers. Oil ring

Caution

The closed coils of valve spring should face
down to combustion chamber.

Put the valve cotters onto valve spring retainer. Top groove
Use a valve cotter remove & assembly tool to 2nd groove
press the valve springs, and then install valves. Oil groove

Caution Valve cotter remove
and assembly tool
In order to avoid damaging the valve stem and
the cylinder head, in the combustion chamber
place a rag between the valve spring
remover/installer as compressing the valve
spring directly.

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

Tap the valve stems gently with a plastic hammer
to make sure valve retainer and valve cotter is
settled.

Caution

Place and hold cylinder head on to working
table so that can prevent from valve damaged.

6-13 7-6

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Measure the outer diameter of piston pin. 6. Cylinder Head / Valve
Service Limit: 16.96 mm
Install camshaft into cylinder head. 2 bolts Cam shaft setting plate
Install valve rocker arm, rocker arm shaft and cam
shaft setting plate.

Measure the inner diameter of connecting rod Cylinder Head Installation Chain guide Gasket
small end. Bolt ×2 Dowel pins
Service Limit: 17.064 mm Clean up all residues and foreign materials onto
the matching surfaces of both cylinder and
Measure the inner diameter of piston pin hole. cylinder head.
Service Limit: 17.02 mm Install chain guide, dowel pins and a new cylinder
Calculate clearance between piston pin and its head gasket onto the cylinder.
hole.
Service Limit: 0.02 mm Caution
Do not damage the matching surfaces of
Measure the piston outer diameter. cylinder and cylinder head.
Caution Avoid residues of gasket or foreign materials
The measurement position is 10 mm distance falling into crankcase as cleaning.
from piston bottom side, and 90° to piston pin.
Install 4 washers and tighten 4 nuts on the cylinder
Service limit head upper side, and then tighten 2 cylinder head
LM25W5: 70.380 mm mounting bolts of cylinder head right side.
LM30W: 72.380 mm Torque value:
Compare measured value with service limit to Nut 3.6~4.0kgf-m
calculate the clearance between piston and Bolt 1.0~1.4kgf-m
cylinder.
Install cam chain on to sprocket and align the 4 nuts
timing mark on the sprocket with that of cylinder Timing mark
head.
Align sprocket bolt hole with camshaft bolt hole. 2 bolts
Tighten the sprocket mounting bolts.
7-5
Caution
Make sure timing marks are matched.

6-14

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6. Cylinder Head / Valve 7. Cylinder / Piston

Install cylinder head side cover (3 bolts). 3 bolts Measure the cylinder upper surface for warpage.
Service limit: 0.05 mm

Tensioner bolts Measure the clearance between piston rings and
ring grooves.
Install thermostat (2 bolts). Service Limit: Top ring: 0.09 mm
Loosen auto tensioner adjustment bolt and
remove bolt and spring. 2nd ring: 0.09 mm
Install tensioner and install spring and adjustment
bolt. Remove piston rings
Check if the piston rings are damaged or its
Install cylinder cover (4 bolts). Thermostat bolts grooves are worn.
4 bolts
Caution
Install Air Injection system (AI) pipe. (4 bolts) 4 bolts Pay attention to remove piston rings because
Install inlet pipe onto cylinder head. they are fragile.
Install and tighten spark plug. 6-15
Torque value: 1.0~2.0kgf-m Place piston rings respective into cylinder below
20 mm of cylinder top. In order to keep the piston
Caution rings in horizontal level in cylinder, push the rings
with piston.
This model is equipped with more precision Measure the piston ring end gap.
4-valve mechanism so its tighten torque can Service Limit: Top ring: 0.50 mm
not be exceeded standard value in order to
avoid causing cylinder head deformation, 2nd ring: 0.65 mm
engine noise and leaking so that motorcycle’s
performance be effected. 7-4

Install the engine onto frame (refer chapter 5).

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Cylinder / Piston Removal 6. Cylinder Head / Valve 4 bolts

Remove cylinder head (refer to chapter 6). Valve Clearance Adjustment
Remove coolant hose from cylinder.
Remove cylinder. Loosen Air Injection system (AI) pipe upper side
bolt (2 bolts).
Remove cylinder head cover.

Coolant hose

Remove the cylinder head side cover. 3 bolts

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. Remove left crankcase cover, and turn the drive Timing mark
Clean up all residues or foreign materials from the face, and align the timing mark on the cam 2 bolts
two matching surfaces of cylinder and crankcase. sprocket with that of cylinder head, piston is at
Top TDC position.
Caution Center Loosen valve clearance adjustment nuts and bolts
Soap the residues into solvent so that the Bottom located on valve rocker arm.
residues can be removed more easily. Measure and adjust valve clearance with feeler
7-3 gauge.
Inspection After valve clearance had been adjusted to
Check if the inner diameter of cylinder is wear out standard value, hold adjustment bolt and then
or damaged. tighten the Adjustment nut.
In the 3 positions, top, center and bottom, of Standard Value: IN 0.10 ± 0.02 mm
cylinder, measure the X and Y values respective in
the cylinder. EX 0.15 ± 0.02 mm
Service limit: Install the cylinder head side cover.
LM25W5: 71.100 mm Start the engine and make sure that engine oil
LM30W: 73.100 mm flows onto the cylinder head.
Stop the engine after confirmed, and then install
the cylinder head cover and AI pipe.

Caution

If lubricant does not flow to cylinder head,
engine components will be worn out seriously.
Thus, it must be confirmed.
When checking lubricant flowing condition, run
the engine in idle speed. Do not accelerate
engine speed.

6-16

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7. Cylinder / Piston 7. Cylinder / Piston

Mechanism Diagram ···························· 7-1 Piston Ring Installation ······················· 7-6 Precautions in Operation
Precautions in Operation ···················· 7-2 Piston Installation ································ 7-7
Troubleshooting··································· 7-2 Cylinder Installation ····························· 7-7 General Information
Cylinder / Piston Removal··················· 7-3 Both cylinder and piston service cannot be carried out when engine mounted on frame.

Mechanism Diagram Specification Unit mm

LM25W5 LM30W

Item Standard Limit Standard Limit

I.D. 70.995~71.015 71.100 72.995~73.015 73.100

0.8~1.2kgf-m Out of round - 0.050 - 0.050
Cylinder
1.0~1.4kgf-m - 0.050 - 0.050
Taper

Warpage - 0.050 - 0.050

Clearance Top 0.015~0.050 0.090 0.015~0.050 0.090
between 2nd
piston ring and 0.015~0.050 0.090 0.015~0.050 0.090
ring groove

Piston/ Piston ring end Too 0.150~0.300 0.500 0.150~0.300 0.500
gap 2nd 0.300~0.450 0.650 0.300~0.450 0.650
Piston Oil
ring (side rail) 0.200~0.700 - 0.200~0.700 -

Piston O.D. (2nd) 70.430~70.480 70.380 72.430~72.480 72.380

Clearance between piston 0.010~0.040 0.100 0.010~0.040 0.100
and cylinder
17.002~17.008 17.020 17.002~17.008 17.020
ID of piston pin boss 16.994~17.000 16.960 16.994~17.000 16.960
0.020 0.020
Piston pin O.D. 0.002~0.014 17.064 0.002~0.014 17.064
17.016~17.034 17.016~17.034
Clearance between piston and piston pin

Connecting rod small end I.D.

Troubleshooting Smoking in Exhaust Pipe
Piston or piston ring worn out
Low or Unstable Compression Pressure Piston ring installation improperly
Cylinder or piston ring worn out Cylinder or piston damage

Knock or Noise Engine Overheat
Cylinder or piston ring worn out Carbon deposits on cylinder head top side
Carbon deposits on cylinder head top-side Cooling pipe clogged or not enough in coolant
Piston pin hole and piston pin wear out flow

7-1 7-2