oil level YAMAHA YZ450F 2008 Owners Manual

3-2
MAINTENANCE INTERVALS
Replace●
TRANSMISSION
Inspect
●
Replace bearing●
SHIFT FORK, SHIFT CAM,
GUIDE BAR
Inspect
●Inspect wear.
ROTOR NUT
Retighten
●●
EXHAUST PIPE, SILENCER,
PROTECTOR
Inspect and retighten
●●
Clean●
Replace●* Whichever comes first
CRANK
Inspect and clean
●●
CARBURETOR
Inspect, adjust and clean
●●
SPARK PLUG
Inspect and clean
●●
Replace●
DRIVE CHAIN Use chain lube.
Lubricate, slack, alignment
●●Chain slack: 48–58 mm (1.9–2.3 in)
Replace
●
COOLING SYSTEM
Check coolant level and leakage
●●
Check radiator cap operation●
Replace coolant●Every two years
Inspect hoses
●
OUTSIDE NUTS AND BOLTS
Retighten
●●Refer to "STARTING AND BREAK-
IN" section in the CHAPTER 1.
AIR FILTER
Clean and lubricate
●●Use foam air-filter oil or equivalent oil.
Replace
●
OIL FILTER
Replace
●●
FRAME
Clean and inspect
●●
FUEL TANK, COCK
Clean and inspect
●●
BRAKES
Adjust lever position and pedal
height
●●
ItemAfter
break-
inEvery
race
Every
third
(or 500
km)Every
fifth (or
1,000
km)
As re-
quiredRemarks

3-3
MAINTENANCE INTERVALS
Lubricate pivot point●●
Check brake disc surface●●
Check fluid level and leakage●●
Retighten brake disc bolts, cali-
per bolts, master cylinder bolts
and union bolts●●
Replace pads●
Replace brake fluid●Every one year
FRONT FORKS
Inspect and adjust
●●
Replace oil●●Suspension oil "S1"
Replace oil seal
●
FRONT FORK OIL SEAL AND
DUST SEAL
Clean and lube
●●Lithium base grease
PROTECTOR GUIDE
Replace
●
REAR SHOCK ABSORBER
Inspect and adjust
●●
Lube●
(After
rain
ride)
●Molybdenum disulfide grease
Replace spring seat
●Every one year
Retighten
●●
DRIVE CHAIN GUIDE AND
ROLLERS
Inspect
●●
SWINGARM
Inspect, lube and retighten
●●Molybdenum disulfide grease
RELAY ARM, CONNECTING
ROD
Inspect, lube and retighten
●●Molybdenum disulfide grease
STEERING HEAD
Inspect free play and retighten
●●
Clean and lube●Lithium base grease
Replace bearing
●
TIRE, WHEELS
Inspect air pressure, wheel run-
out, tire wear and spoke loose-
ness
●●
Retighten sprocket bolt●●
Inspect bearings●
Replace bearings●
Lubricate●Lithium base grease ItemAfter
break-
inEvery
race
Every
third
(or 500
km)Every
fifth (or
1,000
km)
As re-
quiredRemarks

3-4
PRE-OPERATION INSPECTION AND MAINTENANCE
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCETHROTTLE, CONTROL CABLE
Check routing and connection
●●Yamaha cable lube or SAE 10W-30
motor oil
Lubricate
●●
HOT STARTER, CLUTCH LEVER
Inspect free play
●
ItemAfter
break-
inEvery
race
Every
third
(or 500
km)Every
fifth (or
1,000
km)
As re-
quiredRemarks
Item Routine Page
CoolantCheck that coolant is filled up to the radiator cap. Check the cool-
ing system for leakage.P.3-5 – 6
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the fuel
line for leakage.P.1-8
Engine oilCheck that the oil level is correct. Check the crankcase and oil line
for leakage.P.3-8 – 9
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-6
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-6 – 7
Brakes Check the play of front brake and effect of front and rear brake. P.3-13 – 15
Drive chainCheck drive chain slack and alignment. Check that the drive chain
is lubricated properly.P.3-16
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-19
SteeringCheck that the handlebar can be turned smoothly and have no ex-
cessive play.P.3-19 – 20
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage.
P.3-17 – 19
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.4-3 – 4
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-15 – 16
Lubrication Check for smooth operation. Lubricate if necessary. P.3-21
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-11
Lead connectorsCheck that the CDI 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.7-1 – 10

3-5
ENGINE
ENGINE
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:
• Engine guard "1"
• Coolant drain bolt "2"
3. Remove:
• Radiator cap
Drain the coolant completely.
4. Clean:
• Cooling system
Thoroughly flush the cooling sys-
tem with clean tap water.
5. Install:
• Copper washer
• Coolant drain bolt
• Engine guard
• Bolt (engine guard)
6. 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.
Handling notes of coolant:
The coolant is harmful so it should be
handled with special care.
• When coolant splashes to your
eye.
Thoroughly wash your eye with
water and see your doctor.
• When coolant splashes to your
clothes.
Quickly wash it away with water
and then with soap.
• When coolant is swallowed.
Quickly make him vomit and take
him to a doctor.
7. Install:
• Radiator cap
Start the engine and warm it up
for a several minutes.
8. Check:
• Coolant level
Coolant level low
→Add coolant.
CHECKING THE RADIATOR CAP
1. Inspect:
• Seal (radiator cap) "1"
• Valve and valve seat "2"
Crack/damage
→Replace.
Exist fur deposits "3"
→Clean or
replace.
CHECKING THE RADIATOR CAP
OPENING PRESSURE
1. Attach:
• Radiator cap tester "1" and adapt-
er "2"
Coolant drain bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (engine guard):
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:
0.99 L (0.87 Imp qt, 1.05
US qt)
Radiator cap tester:
YU-24460-01/90890-
01325
Radiator cap tester
adapter:
YU-33984/90890-01352

3-8
ENGINE
CHECKING THE ENGINE OIL
LEVEL
1. Stand the machine on a level sur-
face.
• When checking the oil level make
sure that the machine is upright.
• Place the machine on a suitable
stand.
Never remove the oil tank cap just
after high speed operation. The
heated oil could spurt out. causing
danger. Wait until the oil cools
down to approximately 70°C
(158°F).
2. Idle the engine more than 3 min-
utes while keeping the machine
upright. Then stop the engine and
inspect the oil level.
3. Remove:
• Oil tank cap 1
4. Inspect:
• Oil level
Check that the engine oil is above
the level mark "a" and that the oil
does not come out when the
check bolt "1" is removed.
Below the level mark "a"
→Add oil
through the filler cap hole until it is
above the level mark "a".
Oil comes out at the check bolt
→
Drain the oil until it stops coming
out.
When inspecting the oil level, do not
screw the oil level gauge into the oil
tank. Insert the gauge lightly.
(For USA and CDN)
• Do not add any chemical addi-
tives. Engine oil also lubricates
the clutch and additives could
cause clutch slippage.
• Do not allow foreign material to
enter the crankcase.
(Except for USA and CDN)
• Do not add any chemical addi-
tives or use oils with a grade of
CD "a" or higher.
• Do not use oils labeled "ENERGY
CONSERVING II" "b" or higher.
Engine oil also lubricates the
clutch and additives could cause
clutch slippage.• Do not allow foreign material to
enter the crankcase.
5. Start the engine and let it warm up
for several minutes.
When the oil tank is empty, never
start the engine.
6. Idle the engine more than 10 sec-
onds while keeping the machine
upright. Then stop the engine and
add the oil to the maximum level.
7. Install:
• Oil tank cap
CHANGING THE ENGINE OIL
1. Start the engine and let it warm up
for several minutes.
2. Stop the engine and place an oil
pan under the drain bolt.
3. Remove:
• Oil tank plug "1"
• Oil filler cap "2"
• Drain bolt (with gasket) "3"
• Oil filter drain bolt (O-ring) "4"
• Drain bolt (with gasket) "5"
Drain the crankcase and oil tank
of its oil.
4. If the oil filter is to be replaced dur-
ing this oil change, remove the fol-
lowing parts and reinstall them.
Recommended oil:
Yamalube 4,
SAE10W30 or
SAE20W40
Yamalube 4-R,
SAE10W50
API service SG type or
higher, JASO standard
MA
Recommended oil:
SAE10W30,
SAE10W40,
SAE15W40, SAE20W40
or SAE20W50
API service SG type or
higher, JASO standard
MA

3-9
ENGINE
Replacement steps:
a. Remove the oil filter element cov-
er "1" and oil filter element "2".
b. Check the O-rings "3", if cracked
or damaged, replace them with a
new one.
c. Install the oil filter element and oil
filter element cover.
5. Install:
• Gaskets
• Oil filter drain bolt
• Drain bolt (right crankcase)
• Drain bolt (left crankcase)
6. Fill:
• Engine oil7. Install:
• Oil filler cap
8. Inspect:
• Engine (for oil leaks)
• Oil level
Refer to "ENGINE OIL LEVEL IN-
SPECTION".
CHECKING THE OIL PRESSURE
1. Check:
• Oil pressure
Checking steps:
a. Slightly loosen the oil pressure
check bolt "1".
b. Start the engine and keep it idling
until oil starts to seep from the oil
pressure check bolt. If no oil
comes out after one minute, turn
the engine off so it will not seize.
c. Check oil passages and oil pump
for damage or leakage.
d. Start the engine after solving the
problem(s) and recheck the oil
pressure.
e. Tighten the oil pressure check
bolt.
ADJUSTING THE PILOT SCREW
1. Adjust:
• Pilot screw "1"
Adjustment steps:
To optimize the fuel flow at a smaller
throttle opening, each machine's pilot
screw has been individually set at the
factory. Before adjusting the pilot
screw, turn it in fully and count the
number of turns. Record this number
as the factory-set number of turns
out.
a. Turn in the pilot screw until it is
lightly seated.
b. Turn out the pilot screw by the
factory-set number of turns.
ADJUSTING THE ENGINE IDLING
SPEED
1. Start the engine and thoroughly
warm it up.
2. Adjust:
• Engine idling speed
Adjustment steps:
a. Adjust the pilot screw.
Refer to "ADJUSTING THE PI-
LOT SCREW" section.
b. Turn the throttle stop screw "1"
until the specified engine idling
speed.
Using a digital engine tachometer for
idle speed adjustment, detect the en-
gine idling speed by bringing the
sensing element "c" of the engine ta-
chometer close to the ignition coil "2".
Oil filter element cover:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Oil filter drain bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Drain bolt (right crank-
case):
20 Nm (2.0 m•kg, 14
ft•lb)
Drain bolt (left crank-
case):
20 Nm (2.0 m•kg, 14
ft•lb)
Oil quantity:
Periodic oil change:
0.95 L (0.84 Imp qt,
1.00 US qt)
With oil filter replace-
ment:
1.0 L (0.88 Imp qt, 1.06
US qt)
Total amount:
1.2 L (1.06 Imp qt, 1.27
US qt)
Oil pressure check bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Pilot screw (example):
1-1/2 turns out
Digital tachometer:
YU-39951-B/90890-
06760
To increase idle speed
→Turn the
throttle stop screw "1" in "a".
To decrease idle speed
→Turn
the throttle stop screw "1" out
"b".
Engine idling speed:
1,900–2,100 r/min

4-35
OIL FILTER ELEMENT AND WATER PUMP
REMOVING THE IMPELLER
SHAFT
1. Remove:
• Impeller "1"
• Washer "2"
• Impeller shaft "3"
Hold the impeller shaft on its width
across the flats "a" with spanners,
etc. and remove the impeller.
REMOVING THE OIL SEAL
It is not necessary to disassemble the
water pump, unless there is an abnor-
mality such as excessive change in
coolant level, discoloration of coolant,
or milky transmission oil.
1. Remove:
• Bearing "1"
• Oil seal "2"
CHECKING THE IMPELLER SHAFT
1. Inspect:
• Impeller shaft "1"
Bend/wear/damage
→Replace.
Fur deposits
→Clean.CHECKING THE BEARING
1. Inspect:
•Bearing
Rotate inner race with a finger.
Rough spot/seizure
→Replace.
CHECKING THE OIL SEAL
1. Inspect:
• Oil seal "1"
Wear/damage
→Replace.
INSTALLING THE OIL SEAL
1. Install:
• Oil seal "1"
• Apply the lithium soap base grease
on the oil seal lip.
• Install the oil seal with its manufac-
ture's marks or numbers facing the
right crankcase cover "2".
2. Install:
•Bearing "1"
Install the bearing by pressing its out-
er race parallel.
INSTALLING THE IMPELLER
SHAFT
1. Install:
• Impeller shaft "1"
• Washer "2"
• Impeller "3"
• Take care so that the oil seal lip is
not damaged or the spring does not
slip off its position.
• When installing the impeller shaft,
apply the engine oil on the oil seal
lip, bearing and impeller shaft. And
install the shaft while turning it.
• Hold the impeller shaft on its width
across the flats "a" with spanners,
etc. and install the impeller.
INSTALLING THE RIGHT
CRANKCASE COVER
1. Install:
• Dowel pin "1"
• O-ring "2"
•Collar "3"
• Gasket "4"
Apply the lithium soap base grease
on the O-ring.
Impeller:
14 Nm (1.4 m•kg, 10
ft•lb)

5-14
FRONT BRAKE AND REAR BRAKE
4. Install:
• Copper washer "1"
• Brake hose "2"
• Union bolt "3"
Always use new copper washers.
Install the brake hose so that its
pipe portion "a" directs as shown
and lightly touches the projection
"b" on the brake master cylinder.
INSTALLING THE REAR BRAKE
HOSE
1. Install:
• Copper washer "1"
• Brake hose "2"
• Union bolt "3"
Always use new copper washers.
Install the brake hose so that its
pipe portion "a" directs as shown
and lightly touches the projection
"b" on the brake caliper.
2. Install:
• Brake hose holder "1"
• Screw (brake hose holder) "2"
After installing the brake hose
holders, make sure the brake hose
does not contact the spring (rear
shock absorber). If it does, correct
its twist.
FILLING THE BRAKE FLUID
1. Fill:
•Brake fluid
Until the fluid level reaches
"LOWER" level line "a".
• Use only the designated quality
brake fluid:
otherwise, the rubber seals may
deteriorate, causing leakage and
poor brake performance.
• Refill with the same type of brake
fluid;
mixing fluids may result in a
harmful chemical reaction and
lead to poor performance.
• Be careful that water does not
enter the master cylinder when
refilling. Water will significantly lower the boiling point of the flu-
id and may result in vapor lock.
Brake fluid may erode painted sur-
faces or plastic parts. Always
clean up spilled fluid immediately.
A. Front
B. Rear
2. Air bleed:
• Brake system
Refer to "BLEEDING THE HY-
DRAULIC BRAKE SYSTEM" sec-
tion in the CHAPTER 3.
3. Inspect:
• Brake fluid level
Fluid at lower level
→Fill up.
Refer to "CHECKING THE
BRAKE FLUID LEVEL" section in
the CHAPTER 3.
4. Install:
• Reservoir float (front brake)
• Diaphragm
• Brake master cylinder cap "1"
• Screw (brake master cylinder
cap) "2"
After installation, while pulling the
brake lever in or pushing down on
the brake pedal, check whether
there is any brake fluid leaking
where the union bolts are installed
respectively at the brake master
cylinder and brake caliper.
Union bolt:
30 Nm (3.0 m•kg, 22
ft•lb)
Union bolt:
30 Nm (3.0 m•kg, 22
ft•lb)
Screw (brake hose hold-
er):
2 Nm (0.2 m•kg, 1.4
ft•lb)
Recommended brake flu-
id:
DOT #4
Screw (bolt) {brake mas-
ter cylinder cap}:
2 Nm (0.2 m•kg, 1.4
ft•lb)

5-19
FRONT FORK
Contamination →Clean.
• O-ring "2"
Wear/damage
→Replace.
• Piston metal "3"
Wear/damage
→Replace.
• Spring "4"
Damage/fatigue
→Replace base
valve.
• Air bleed screw "5"
Wear/damage
→Replace.
CHECKING THE COLLAR
1. Inspect:
• Piston metal "1"
Wear/damage
→Replace.
CHECKING THE FORK SPRING
1. Measure:
• Fork spring free length "a"
Out of specification
→Replace.
CHECKING THE INNER TUBE
1. Inspect:
• Inner tube surface "a"
Score marks
→Repair or replace.
Use #1,000 grit wet sandpaper.
Damaged oil lock piece
→Re-
place.
• Inner tube bends
Out of specification
→Replace.
Use the dial gauge "1".
The bending value is shown by one half of the dial gauge reading.
Do not attempt to straighten a bent
inner tube as this may dangerous-
ly weaken the tube.
CHECKING THE OUTER TUBE
1. Inspect:
• Outer tube "1"
Score marks/wear/damage
→Re-
place.
CHECKING THE ADJUSTER
1. Inspect:
•Adjuster "1"
• O-ring "2"
Wear/damage
→Replace.
ASSEMBLING THE FRONT FORK
1. Wash the all parts in a clean sol-
vent.
2. Stretch the damper assembly ful-
ly.
3. Fill:
• Front fork oil "1"
To damper assembly.
• Be sure to use recommended
fork oil. If other oils are used,
they may have an excessively ad-
verse effect on the front fork per-
formance.
• Never allow foreign materials to enter the front fork.
4. After filling, pump the damper as-
sembly "1" slowly up and down
(about 200 mm (7.9 in) stroke)
several times to bleed the damper
assembly of air.
Be careful not to excessive full stroke.
A stroke of 200 mm (7.9 in) or more
will cause air to enter. In this case, re-
peat the steps 2 to 4.
5. Measure:
• Oil level (left and right) "a"
Out of specification
→ Adjust.
6. Tighten:
• Locknut "1"
Fully finger tighten the locknut onto
the damper assembly.
Fork spring free length:
454 mm (17.9 in)
: 449 mm (17.7
in)
Inner tube bending limit:
0.2 mm (0.008 in)
Recommended oil:
Suspension oil "S1"
Oil capacity:
199 cm
3 (7.00 Imp oz,
6.73 US oz)
Standard oil level:
145-148 mm (5.71-5.83
in)
From top of fully
stretched damper as-
sembly.

7-6
CHASSIS
CHASSIS
SELECTION OF THE SECONDARY
REDUCTION RATIO (SPROCKET)
ondary gear reduction ratio>
• It is generally said that the second-
ary gear ratio should be reduced for
a longer straight portion of a speed
course and should be increased for
a course with many corners. Actual-
ly, however, as the speed depends
on the ground condition of the day
of the race, be sure to run through
the circuit to set the machine suit-
able for the entire course.
• In actuality, it is very difficult to
achieve settings suitable for the en-
tire course and some settings may
be sacrificed. Thus, the settings
should be matched to the portion of
the course that has the greatest ef-
fect on the race result. In such a
case, run through the entire course
while making notes of lap times to
find the best balance; then, deter-
mine the secondary reduction ratio.
• If a course has a long straight por-
tion where a machine can run at
maximum speed, the machine is
generally set such that it can devel-
op its maximum revolutions toward
the end of the straight line, with care
taken to avoid the engine over-rev-
ving.
Riding technique varies from rider to
rider and the performance of a ma-
chine also vary from machine to ma-
chine. Therefore, do not imitate other
rider's settings from the beginning but
choose your own setting according to
the level of your riding technique.
DRIVE AND REAR WHEEL
SPROCKETS SETTING PARTS
TIRE PRESSURE
Tire pressure should be adjust to suit
the road surface condition of the cir-
cuit.
• Under a rainy, muddy, sandy, or
slippery condition, the tire pressure
should be lower for a larger area of
contact with the road surface.
• Under a stony or hard road condi-
tion, the tire pressure should be
higher to prevent a flat tire.
FRONT FORK SETTING
The front fork setting should be made
depending on the rider's feeling of an
actual run and the circuit conditions.The front fork setting includes the fol-
lowing three factors:
1. Setting of air spring characteris-
tics
• Change the fork oil amount.
2. Setting of spring preload
• Change the spring.
3. Setting of damping force
• Change the compression damp-
ing.
• Change the rebound damping.
The spring acts on the load and
the damping force acts on the
cushion travel speed.
CHANGE IN AMOUNT AND
CHARACTERISTICS OF FORK OIL
Damping characteristic near the final
stroke can be changed by changing
the fork oil amount.
Adjust the oil amount in 5 cm3 (0.2
Imp oz, 0.2 US oz) increments or
decrements. Too small oil amount
causes the front fork to produce a
noise at full rebound or the rider to
feel some pressure on his hands
or body. Alternatively, too large oil
amount will cause the air spring
characteristics to have a tendency
to be stiffer with the consequent
deteriorated performance and
characteristics. Therefore, adjust
the front fork within the specified
range.
A. Air spring characteristics in
relation to oil amount change
B. Load Secondary reduction ratio =
Number of rear wheel sprocket
teeth/Number of drive sprocket
teeth
Standard secondary
reduction ratio49/13
(3.769)
Part name Size Part number
Drive
sprocket "1"
(STD) 13T 9383B-13233
Rear wheel
sprocket "2"
47T 1C3-25447-00
48T 1C3-25448-00
(STD) 49T 1C3-25449-00
50T 1C3-25450-00
51T 1C3-25451-00
52T 1C3-25452-00
Standard tire pressure:
100 kPa (1.0 kgf/cm
2,
15 psi)
Extent of adjustment:
60–80 kPa (0.6–0.8 kgf/
cm
2, 9.0–12 psi)
Extent of adjustment:
100–120 kPa (1.0–1.2
kgf/cm
2, 15–18 psi)
Standard oil amount:
350 cm3 (12.3 Imp oz,
11.8 US oz)
Extent of adjustment:
300–375 cm
3(10.6–13.2
Imp oz, 10.1–12.7 US
oz)