check engine YAMAHA WR 450F 2008 Owners Manual
[x] Cancel search | Manufacturer: YAMAHA, Model Year: 2008, Model line: WR 450F, Model: YAMAHA WR 450F 2008Pages: 224, PDF Size: 13.7 MB
Page 6 of 224

FOREWORD
INTRODUCTION
Congratulations on your purchase of 
a Yamaha WR series. This model is 
the culmination of Yamaha's vast ex-
perience in the production of paceset-
ting racing machines. It represents 
the highest grade of craftsmanship 
and reliability that have made Yama-
ha a leader.
This manual explains operation, in-
spection, basic maintenance and tun-
ing of your machine. If you have any 
questions about this manual or your 
machine, please contact your Yama-
ha dealer.
Yamaha continually seeks advance-
ments in product design and quality. 
Therefore, while this manual contains 
the most current product information 
available at the time of printing, there 
may be minor discrepancies between 
your machine and this manual. If you 
have any questions concerning this 
manual, please consult your Yamaha 
dealer.
PLEASE READ THIS MANUAL 
CAREFULLY AND COMPLETELY 
BEFORE OPERATING THIS MA-
CHINE. DO NOT ATTEMPT TO OP-
ERATE THIS MACHINE UNTIL YOU 
HAVE ATTAINED A SATISFACTO-
RY KNOWLEDGE OF ITS CON-
TROLS AND OPERATING 
FEATURES AND UNTIL YOU HAVE 
BEEN TRAINED IN SAFE AND 
PROPER RIDING TECHNIQUES. 
REGULAR INSPECTIONS AND 
CAREFUL MAINTENANCE, 
ALONG WITH GOOD RIDING 
SKILLS, WILL ENSURE THAT YOU 
SAFETY ENJOY THE CAPABILI-
TIES AND THE RELIABILITY OF 
THIS MACHINE.
PARTICULARLY IMPORTANT 
INFORMATION
The Safety Alert Symbol means AT-
TENTION! BECOME ALERT! YOUR 
SAFETY IS INVOLVED!Failure to follow WARNING instruc-
tions could result in severe injury or 
death to the machine operator, a by-
stander, or a person inspecting or re-
pairing the machine.
A CAUTION indicates special pre-
cautions that must be taken to avoid 
damage to the machine.
A NOTE provides key information to 
make procedures easier or clearer.
IMPORTANT NOTICE
THIS MACHINE IS DESIGNED 
STRICTLY FOR COMPETITION 
USE, ONLY ON A CLOSED 
COURSE.  It is illegal for this machine 
to be operated on any public street, 
road, or highway. Off-road use on 
public lands may be illegal. Please 
check local regulations before riding.
1. THIS MACHINE IS TO BE OP-
ERATED BY AN EXPERI-
ENCED RIDER ONLY.
Do not attempt to operate this 
machine at maximum power 
until you are totally familiar 
with its characteristics.
2. THIS MACHINE IS DESIGNED 
TO BE RIDDEN BY THE OP-
ERATOR ONLY.
Do not carry passengers on 
this machine.
3. ALWAYS WEAR PROTEC-
TIVE APPAREL.
When operating this ma-
chine, always wear an ap-
proved helmet with goggles 
or a face shield. Also wear 
heavy boots, gloves, and pro-
tective clothing. Always wear 
proper fitting clothing that 
will not be caught in any of 
the moving parts or controls 
of the machine.
4. ALWAYS MAINTAIN YOUR 
MACHINE IN PROPER 
WORKING ORDER.
For safety and reliability, the 
machine must be properly 
maintained. Always perform 
the pre-operation checks in-
dicated in this manual. Cor-
recting a mechanical problem 
before you ride may prevent 
an accident.
5. GASOLINE IS HIGHLY FLAM-
MABLE.
Always turn off the engine 
while refueling. Take care to 
not spill any gasoline on the 
engine or exhaust system. 
Never refuel in the vicinity of 
an open flame, or while 
smoking.
6. GASOLINE CAN CAUSE IN-
JURY.
If you should swallow some 
gasoline, inhale excess gaso-
line vapors, or allow any gas-
oline to get into your eyes, 
contact a doctor immediately. 
If any gasoline spills onto 
your skin or clothing, imme-
diately wash skin areas with 
soap and water, and change 
your clothes.
7. ONLY OPERATE THE MA-
CHINE IN AN AREA WITH AD-
EQUATE VENTILATION.
Never start the engine or let it 
run for any length of time in 
an enclosed area. Exhaust 
fumes are poisonous. These 
fumes contain carbon mon-
oxide, which by itself is odor-
less and colorless. Carbon 
monoxide is a dangerous gas 
which can cause uncon-
sciousness or can be lethal.
8. PARK THE MACHINE CARE-
FULLY; TURN OFF THE EN-
GINE.
Always turn off the engine if 
you are going to leave the 
machine. Do not park the ma-
chine on a slope or soft 
ground as it may fall over. 
Page 10 of 224

CONTENTS
CHAPTER 1
GENERAL INFOR-
MATION
DESCRIPTION ................. 1-1
MACHINE 
IDENTIFICATION ............. 1-2
INCLUDED PARTS .......... 1-2
IMPORTANT 
INFORMATION................. 1-2
CHECKING OF CONNEC-
TION ................................. 1-3
SPECIAL TOOLS ............. 1-4
CONTROL FUNCTIONS .. 1-8
MULTI-FUNCTION 
DISPLAY .......................... 1-9
STARTING AND 
BREAK-IN ...................... 1-14
TORQUE-CHECK 
POINTS........................... 1-16
CLEANING AND 
STORAGE ...................... 1-17
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICA-
TIONS ............................... 2-1
MAINTENANCE 
SPECIFICATIONS ............ 2-4
TIGHTENING 
TORQUES ...................... 2-13
LUBRICATION 
DIAGRAMS .................... 2-19
CABLE ROUTING 
DIAGRAM ....................... 2-21
CHAPTER 3
REGULAR INSPEC-
TION AND AD-
JUSTMENTS
MAINTENANCE 
INTERVALS ...................... 3-1
PRE-OPERATION 
INSPECTION AND 
MAINTENANCE................ 3-5
ENGINE ............................ 3-6
CHASSIS ........................ 3-17
ELECTRICAL ................. 3-27
CHAPTER 4
TUNING
ENGINE ............................ 4-1
CHASSIS .......................... 4-5
CHAPTER 5
ENGINE
RADIATOR ....................... 5-1
CARBURETOR................. 5-4
AIR INDICTOIN 
SYSTEM ......................... 5-13
CAMSHAFTS.................. 5-15
CYLINDER HEAD........... 5-20
VALVES AND VALVE 
SPRINGS ........................ 5-23
CYLINDER AND 
PISTON ........................... 5-27
CLUTCH ......................... 5-30
OIL FILTER ELEMENT 
AND WATER PUMP ....... 5-34
BALANCER .................... 5-38
OIL PUMP ....................... 5-40
KICK SHAFT AND SHIFT 
SHAFT ............................ 5-43
AC MAGNETO AND 
STARTER CLUTCH ....... 5-48
ENGINE REMOVAL ....... 5-53CRANKCASE AND 
CRANKSHAFT ...............5-57
TRANSMISSION, SHIFT 
CAM AND SHIFT 
FORK ..............................5-63
CHAPTER 6
CHASSIS
FRONT WHEEL AND 
REAR WHEEL ..................6-1
FRONT BRAKE AND 
REAR BRAKE ..................6-6
FRONT FORK .................6-16
HANDLEBAR..................6-23
STEERING ......................6-27
SWINGARM ....................6-31
REAR SHOCK 
ABSORBER ....................6-36
CHAPTER 7
ELECTRICAL
ELECTRICAL COMPO-
NENTS AND WIRING DIA-
GRAM ...............................7-1
IGNITION SYSTEM...........7-3
ELECTRIC STARTING 
SYSTEM............................7-5
CHARGING SYSTEM .....7-13
THROTTLE POSITION 
SENSOR SYSTEM .........7-15
LIGHTING SYSTEM .......7-18
SIGNALING SYSTEM.....7-20 
Page 24 of 224

1-14
STARTING AND BREAK-IN
STARTING AND BREAK-IN
FUEL
Always use the recommended fuel as 
stated below. Also, be sure to use 
new gasoline the day of a race.
Use only unleaded gasoline. The 
use of leaded gasoline will cause 
severe damage to the engine inter-
nal parts such as valves, piston 
rings, and exhaust system, etc.
If knocking or pinging occurs, use a 
different brand of gasoline or higher 
octane grade.
• For refueling, be sure to stop the 
engine and use enough care not 
to spill any fuel. Also be sure to 
avoid refueling close to a fire.
• Refuel after the engine, exhaust 
pipe, etc. have cooled off.
HANDLING NOTE
Never start or run the engine in a 
closed area. The exhaust fumes 
are poisonous; they can cause 
loss of consciousness and death 
in a very short time. Always oper-
ate the machine in a well-ventilated 
area.
• The carburetor on this machine 
has a built-in accelerator pump. 
Therefore, when starting the en-
gine, do not operate the throttle 
or the spark plug will foul.
• Unlike a two-stroke engine, this 
engine cannot be kick started 
when the throttle is open be-
cause the kickstarter may kick 
back. Also, if the throttle is open 
the air/fuel mixture may be too 
lean for the engine to start.
• Before starting the machine, per-
form the checks in the pre-opera-
tion check list.
AIR FILTER MAINTENANCE
According to "CLEANING THE AIR 
FILTER ELEMENT" section in the 
CHAPTER 3, apply the foam-air-filter 
oil or its equivalent to the element. 
(Excess oil in the element may ad-
versely affect engine starting.)
STARTING A COLD ENGINE
This model is equipped with an igni-
tion circuit cut-off system. The engine 
can be started under the following 
conditions.
• When the transmission is in neutral.
• When the clutch is disengaged with 
the transmission in any position. 
However, it is recommended to shift 
into neutral before starting the en-
gine.
1. Inspect the coolant level.
2. Turn the fuel cock to "ON".
3. Push on the main switch to "ON".
4. Shift the transmission into neutral.
5. Fully open the cold starter knob 
"1".
6. Start the engine by pushing the 
start switch or by kicking the kick-
starter crank.
If the engine fails to start by pushing 
the start switch, release the switch, 
wait a few seconds, and then try 
again. Each starting attempt should 
be as short as possible to preserve 
the battery. Do not crank the engine 
more than 10 seconds on any one at-
tempt. If the engine does not start 
with the starter motor, try using the 
kickstarter crank.
• If the starter motor will not turn 
when pushing the start switch, 
stop pushing it immediately and 
kick start the engine in order to 
avoid the load on the motor.
• Do not open the throttle while 
kicking the kickstarter crank. 
Otherwise, the kickstarter crank 
may kick back.
7. Return the cold starter knob to its 
original position and run the en-
gine at 3,000–5,000 r/min for 1 or 
2 minutes.
Since this model is equipped with an 
accelerator pump, if the engine is 
raced (the throttle opened and 
closed), the air/fuel mixture will be too 
rich and the engine may stall. Also 
unlike a two-stroke engine, this model 
can idle.
Do not warm up the engine for ex-
tended periods of time.
STARTING A WARM ENGINE
Do not operate the cold starter knob 
and throttle. Pull the hot starter lever 
"1" and start the engine by pushing 
the start switch or by kicking the kick-
starter crank forcefully with a firm 
stroke. As soon as the engine starts, 
Release the hot starter lever to close 
the air passage.
Restarting an engine after a fall
Pull the hot starter lever and start the 
engine. As soon as the engine starts, 
Release the hot starter lever to close 
the air passage. Recommended fuel:
Premium unleaded 
gasoline only with a re-
search octane number 
of 95 or higher. 
Page 25 of 224

1-15
STARTING AND BREAK-IN
The engine fails to start
Pull the hot starter lever all the way 
out and while holding the lever, kick 
the kickstarter crank 10 to 20 times to 
clear the engine. Then, restart the en-
gine. Refer to "Restarting an engine 
after a fall".
Observe the following break-in 
procedures during initial operation 
to ensure optimum performance 
and avoid engine damage.
BREAK-IN PROCEDURES
1. Before starting the engine, fill the 
fuel tank with the fuel.
2. Perform the pre-operation checks 
on the machine.
3. Start and warm up the engine. 
Check the idle speed, and check 
the operation of the controls and 
the engine stop switch. Then, re-
start the engine and check its op-
eration within no more than 5 
minutes after it is restarted.4. Operate the machine in the lower 
gears at moderate throttle open-
ings for five to eight minutes.
5. Check how the engine runs when 
the machine is ridden with the 
throttle 1/4 to 1/2 open (low to me-
dium speed) for about one hour.
6. Restart the engine and check the 
operation of the machine through-
out its entire operating range. Re-
start the machine and operate it 
for about 10 to 15 more minutes. 
The machine will now be ready to 
race.
• After the break-in or before each 
race, you must check the entire 
machine for loose fittings and 
fasteners as per "TORQUE-
CHECK POINTS". Tighten all 
such fasteners as required.
• When any of the following parts 
have been replaced, they must 
be broken in.  
CYLINDER AND CRANKSHAFT:
About one hour of break-in oper-
ation is necessary.
PISTON, RING, VALVES, CAM-
SHAFTS AND GEARS:
These parts require about 30 
minutes of break-in operation at 
half-throttle or less. Observe the 
condition of the engine carefully 
during operation.
Thro
ttle 
grip 
op-
era-
tion*Cold 
start-
er 
knobHot 
start-
er le-
ver
St
ar
ti
n
g 
a 
c
ol
d 
e
n
gi
n
eAir tempera-
ture = less 
than 5 °C (41 
°F)Ope
n 3 
or 4 
time
sON OFF
Air tempera-
ture = more 
than 5 °C (41 
°F)Non
eON OFF
Air tempera-
ture (normal 
temperature) 
= between 5 
°C (41 °F) 
and 25 °C 
(77 °F)Non
eON/
OFFOFF
Air tempera-
ture = more 
than 25 °C 
(77 °F)Non
eOFF OFF
Starting an en-
gine after a long 
period of timeNon
eON OFF
Restarting a 
warm engineNon
eOFF ON
Restarting an en-
gine after a fallNon
eOFF ON
* Operate the throttle grip before kick 
starting. 
Page 26 of 224

1-16
TORQUE-CHECK POINTS
TORQUE-CHECK POINTS
Concerning the tightening torque, refer to "TIGHTENING TORQUES" section in the CHAPTER 2.
Frame construction Frame to rear frame
Combined seat and fuel tank Fuel tank to frame
Exhaust system Silencer to rear frame
Engine mounting Frame to engine
Engine bracket to engine
Engine bracket to frame
Steering Steering stem to handlebar Steering stem to frame
Steering stem to upper bracket
Upper bracket to handlebar
Suspension Front Steering stem to front fork Front fork to upper bracket
Front fork to lower bracket
Rear For link type Assembly of links
Link to frame
Link to rear shock absorber
Link to swingarm
Installation of rear shock absorber Rear shock absorber to frame
Installation of swingarm Tightening of pivot shaft
Wheel Installation of wheel Front Tightening of wheel axle
Tightening of axle holder
Rear Tightening of wheel axle
Wheel to rear wheel sprocket
Brake Front Brake caliper to front fork
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to handlebar
Tightening of bleed screw
Tightening of brake hose holder
Rear Brake pedal to frame
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to frame
Tightening of bleed screw
Tightening of brake hose holder
Fuel system Fuel tank to fuel cock
Lubrication system Tightening of oil hose clamp 
Page 40 of 224

2-13
TIGHTENING TORQUES
TIGHTENING TORQUES
ENGINE
△- marked portion shall be checked for torque tightening after break-in or before each race.
*1: Tighten the cylinder head bolts to 30 Nm (3.0 m•kg, 22 ft•lb) in the proper tightening sequence, remove and retighten 
the cylinder head bolts to 20 Nm (2.0 m•kg, 14 ft•lb) in the proper tightening sequence, and then tighten the cylinder head 
bolts further to reach the specified angle 180° in the proper tightening sequence.
Part to be tightened Thread size Q'tyTightening torque
Nm m•kg ft•lb
Spark plug M10S × 1.0 1 13 1.3 9.4
Camshaft cap M6 × 1.0 10 10 1.0 7.2
Cylinder head blind plug screw M12 × 1.0 1 28 2.8 20
Cylinder head (stud bolt) M8 × 1.25 1 15 1.5 11
Cylinder head (bolt) M10 × 1.25 4 Refer to NOTE.*1
Cylinder head (bolt) M6 × 1.0 2 10 1.0 7.2
Cylinder head cover M6 × 1.0 2 10 1.0 7.2
Cylinder M6 × 1.0 1 10 1.0 7.2
Timing chain tensioner M6 × 1.0 2 10 1.0 7.2
Timing chain tensioner cap bolt M6 × 1.0 1 7 0.7 5.1
Timing chain guide (intake side) M6 × 1.0 2 10 1.0 7.2
Exhaust pipe (nut) M8 × 1.25 1 20 2.0 14
Exhaust pipe (bolt) M8 × 1.25 1 20 2.0 14
△Silencer M8 × 1.25 2 30 3.0 22
Silencer clamp M8 × 1.25 1 16 1.6 11
Exhaust pipe protector M6 × 1.0 3 10 1.0 7.2
Spark arrester M5 × 0.8 4 7 0.7 5.1
Silencer cap M5 × 0.8 6 5 0.5 3.6
Air induction pipe M6 × 1.0 2 10 1.0 7.2
Air cut-off valve assembly and bracket M6 × 1.0 2 10 1.0 7.2
Bracket (air cut-off valve) and frame M6 × 1.0 2 7 0.7 5.1
Carburetor joint M6 × 1.0 3 10 1.0 7.2
Carburetor joint clamp M4 × 0.7 1 3 0.3 2.2
△Air filter case M6 × 1.0 2 8 0.8 5.8
Air filter joint clamp M6 × 1.0 1 3 0.3 2.2
Air filter joint and air filter case M5 × 0.8 1 4 0.4 2.9
Throttle cable adjust bolt and locknut M6 × 0.75 1 4 0.4 2.9
Throttle cable (pull) M6 × 1.0 1 4 0.4 2.9
Throttle cable (return) M12 × 1.0 1 11 1.1 8.0
Throttle cable cover M5 × 0.8 2 4 0.4 2.9
Hot starter plunger M12 × 1.0 1 2 0.2 1.4
Hot starter cable adjust bolt and locknut M6 × 0.75 1 4 0.4 2.9
Air filter element M6 × 1.0 1 2 0.2 1.4
Radiator stay M6 × 1.0 6 7 0.7 5.1
Radiator M6 × 1.0 4 10 1.0 7.2
Radiator hose clamp M6 × 1.0 8 2 0.2 1.4 
Page 41 of 224

2-14
TIGHTENING TORQUES
Radiator pipe 1, 2 M10 × 1.0 2 10 1.0 7.2
Impeller M8 × 1.25 1 14 1.4 10
Water pump housing cover M6 × 1.0 3 10 1.0 7.2
Coolant drain bolt M6 × 1.0 1 10 1.0 7.2
Oil pump cover M4 × 0.7 1 2 0.2 1.4
Oil pump M6 × 1.0 2 10 1.0 7.2
Oil pump drive gear shaft M6 × 1.0 1 10 1.0 7.2
Engine oil drain bolt (oil filter)  M6 × 1.0 1 10 1.0 7.2
Oil filter cover M6 × 1.0 2 10 1.0 7.2
Oil check bolt (cylinder head) M6 × 1.0 1 10 1.0 7.2
△Oil hose clamp — 2 2 0.2 1.4
Crankshaft end accessing screw M27 × 1.5 1 10 1.0 7.2
Timing mark accessing screw M14 × 1.5 1 6 0.6 4.3
Clutch cover M6 × 1.0 7 10 1.0 7.2
Crankcase cover (right) M6 × 1.0 8 10 1.0 7.2
Crankcase cover (right) M6 × 1.0 2 12 1.2 8.7
Crankcase cover (left) M6 × 1.0 8 10 1.0 7.2
Idle gear cover (starter motor) M6 × 1.0 2 10 1.0 7.2
Crankcase M6 × 1.0 12 12 1.2 8.7
Clutch cable holder  M6 × 1.0 1 10 1.0 7.2
Oil drain bolt (crankcase right) M6 × 1.25 1 20 2.0 14
Oil drain bolt (crankcase left) M6 × 1.0 1 20 2.0 14
Oil check bolt (crankcase) M6 × 1.0 1 10 1.0 7.2
Oil strainer M6 × 1.0 1 10 1.0 7.2
Crankcase bearing stopper M6 × 1.0 4 14 1.4 10
Crankcase bearing stopper M6 × 1.0 8 10 1.0 7.2
Drive axle oil seal stopper M6 × 1.0 2 10 1.0 7.2
Ratchet wheel guide M6 × 1.0 2 12 1.2 8.7
Kickstarter crank M8 × 1.25 1 33 3.3 24
Screw (kickstarter crank) M6 × 1.0 1 7 0.7 5.1
Starter clutch M6 × 1.0 6 16 1.6 11
Primary drive gear M20 × 1.0 1 110 11.0 80
Clutch boss M20 × 1.0 1 75 7.5 54
Clutch cable adjust bolt and locknut M8 × 1.0 1 4 0.4 2.9
Clutch spring M6 × 1.0 6 10 1.0 7.2
Balancer M10 × 1.0 1 45 4.5 32
Balancer driven gear M14 × 1.0 1 50 5.0 36
Balancer weight plate M6 × 1.0 3 10 1.0 7.2
Drive sprocket M20 × 1.0 1 75 7.5 54
Drive chain sprocket cover M6 × 1.0 2 8 0.8 5.8
Shift pedal M6 × 1.0 1 12 1.2 8.7
Shift guide M6 × 1.0 2 10 1.0 7.2
Stopper lever M6 × 1.0 1 10 1.0 7.2
Segment M8 × 1.25 1 30 3.0 22Part to be tightened Thread size Q'tyTightening torque
Nm m•kg ft•lb 
Page 56 of 224

3-1
MAINTENANCE INTERVALS
REGULAR INSPECTION AND ADJUSTMENTS
MAINTENANCE INTERVALS
The following schedule is intended as a general guide to maintenance and lubrication. Bear in mind that such factors as 
weather, terrain, geographical location, and individual usage will alter the required maintenance and lubrication intervals. If 
you are a doubt as to what intervals to follow in maintaining and lubricating your machine, consult your Yamaha dealer.
ItemAfter 
break-
inEvery 
race
Every 
third 
(or 500 
km)Every 
fifth (or 
1,000 
km)
As re-
quiredRemarks
ENGINE OIL
Replace●●
VALVES
Check the valve clearances●●The engine must be cold.
Inspect●Check the valve seats and valve 
stems for wear.
Replace●
VALVE SPRINGS
Inspect●Check the free length and the tilt.
Replace●
VALVE LIFTERS
Inspect●Check for scratches and wear.
Replace●
CAMSHAFTS Inspect the camshaft surface.
Inspect●Inspect the decompression system.
Replace●
CAMSHAFT SPROCKETS
Inspect●Check for wear on the teeth and for 
damage.
Replace●
PISTON
Inspect●●Inspect crack.
Clean●Inspect carbon deposits and eliminate 
them.
Replace●
PISTON RING
Inspect●Check ring end gap.
Replace●●
PISTON PIN
Inspect●
Replace●
CYLINDER  HEAD Inspect carbon deposits and eliminate 
them.
Inspect and clean●Change gasket.
CYLINDER
Inspect and clean●Inspect score marks.
Replace●Inspect wear. 
Page 60 of 224

3-5
PRE-OPERATION INSPECTION AND MAINTENANCE
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation or practice, make sure the machine is in good operating condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator cap. Check the cool-
ing system for leakage.P.3-9 – 10
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the fuel 
line for leakage.P.1-14
Engine oilCheck that the oil level is correct. Check the crankcase and oil line 
for leakage.P.3-12 – 13
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the 
clutch operates smoothly.P.3-10
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly 
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10 – 11
Brakes Check the play of front brake and effect of front and rear brake. P.3-17 – 20
Drive chainCheck drive chain slack and alignment. Check that the drive chain 
is lubricated properly.P.3-20 – 21
WheelsCheck for excessive wear and tire pressure. Check for loose 
spokes and have no excessive play.P.3-24
SteeringCheck that the handlebar can be turned smoothly and have no ex-
cessive play.P.3-24 – 25
Front forks and rear shock 
absorberCheck that they operate smoothly and there is no oil leakage. 
P.3-21 – 24
Cables (wires)Check that the clutch and throttle cables move smoothly. Check 
that they are not caught when the handlebars are turned or when 
the front forks travel up and down.—
Exhaust pipe Check that the exhaust pipe is tightly mounted and has no cracks. P.3-8 – 9
Rear wheel sprocket  Check that the rear wheel sprocket tightening bolt is not loose.  P.3-20
Lubrication  Check for smooth operation. Lubricate if necessary. P.3-26
Bolts and nuts  Check the chassis and engine for loose bolts and nuts. P.1-16
Lead connectorsCheck that the AC magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-3
SettingsIs the machine set suitably for the condition of the racing course 
and weather or by taking into account the results of test runs be-
fore racing? Are inspection and maintenance completely done?P.4-1 – 9 
Page 64 of 224

3-9
ENGINE
CHECKING THE SILENCER AND 
EXHAUST PIPE
1. Inspect:
• Gasket "1"
Damage→Replace.
INSTALLING THE SILENCER AND 
EXHAUST PIPE
1. Install:
• Gasket 
• Exhaust pipe "1"
• Nut (exhaust pipe) "2"
• Bolt (exhaust pipe) "3"
First, temporarily tighten the nut (ex-
haust pipe), then tighten the bolt (ex-
haust pipe) 13 Nm (1.3 m•kg, 9.4 
ft•lb). After that, retighten the nut (ex-
haust pipe) 20 Nm (2.0 m•kg, 14 ft•lb) 
and then the bolt (exhaust pipe) 20 
Nm (2.0 m•kg, 14 ft•lb).
2. Install:
• Silencer clamp "1"
• Gasket "2" 
• Silencer
• Washer "4"
• Bolt (silencer) "5"CHECKING THE COOLANT LEVEL
Do not remove the radiator cap 
"1", drain bolt and hoses when the 
engine and radiator are hot. Scald-
ing hot fluid and steam may be 
blown out under pressure, which 
could cause serious injury. When 
the engine has cooled, place a 
thick towel over the radiator cap, 
slowly rotate the cap counter-
clockwise to the detent. This pro-
cedure allows any residual 
pressure to escape. When the 
hissing sound has stopped, press 
down on the cap while turning 
counterclockwise and remove it.
Hard water or salt water is harmful 
to the engine parts. You may use 
distilled water, if you can't get soft 
water.
1. Place the machine on a level 
place, and hold it in an upright po-
sition.
2. Remove:
• Radiator cap
3. Check:
• Coolant level "a"
Coolant level low→Add coolant.
1. Radiator
CHANGING THE COOLANT
Do not remove the radiator cap 
when the engine is hot.
Take care so that coolant does not 
splash on painted surfaces. If it 
splashes, wash it away with water.
1. Place a container under the en-
gine.
2. Remove:
• Seat
• Left side cover
3. Remove the catch tank hose from 
the catch tank and drain the tank 
of its coolant.
4. Remove:
• Coolant drain bolt "1"
5. Remove:
• Radiator cap
Drain the coolant completely.
6. Clean:
• Cooling system
Thoroughly flush the cooling sys-
tem with clean tap water.
7. Install:
• Copper washer 
• Coolant drain bolt
8. Fill:
•Radiator
• Engine
To specified level.
• Do not mix more than one type of 
ethylene glycol antifreeze con-
taining corrosion inhibitors for 
aluminum engine.
• Do not use water containing im-
purities or oil.
Nut (exhaust pipe):
20 Nm (2.0 m•kg, 14 
ft•lb)
Bolt (exhaust pipe):
20 Nm (2.0 m•kg, 14 
ft•lb)
Silencer clamp:
16 Nm (1.6 m•kg, 11 
ft•lb)
Bolt (silencer):
30 Nm (3.0 m•kg, 22 
ft•lb)
Coolant drain bolt:
10 Nm (1.0 m•kg, 7.2 
ft•lb)
Recommended coolant:
High quality ethylene 
glycol anti-freeze con-
taining anti-corrosion 
for aluminum engine
Coolant "1" and water 
(soft water) "2" mixing ra-
tio:
50%/50%
Coolant capacity:
1.0 L (0.88 Imp qt, 1.06 
US qt)