2008 YAMAHA YZ450F recommended oil

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

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)

5-18
FRONT FORK
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
The front fork requires careful atten-
tion. So it is recommended that the
front fork be maintained at the deal-
ers.
To prevent an accidental explosion
of air, the following instructions
should be observed:
• The front fork with a built-in pis-
ton rod has a very sophisticated
internal construction and is par-
ticularly sensitive to foreign ma-
terial. Use enough care not to
allow any foreign material to
come in when the oil is replaced
or when the front fork is disas-
sembled and reassembled.
• Before removing the base valves
or front forks, be sure to extract
the air from the air chamber com-
pletely.
REMOVING THE DAMPER
ASSEMBLY
1. Loosen:
• Damper assembly "1"
Before removing the front fork from
the machine, loosen the damper as-
sembly with the cap bolt ring wrench
"2".
REMOVING THE ADJUSTER
1. Drain the outer tube of its front
fork oil at its top.
2. Loosen:
•Adjuster "1"3. Remove:
•Adjuster "1"
• While compressing the inner tube
"2", set the cap bolt ring wrench "4"
between the inner tube and locknut
"3".
• Hold the locknut and remove the
adjuster.
Do not remove the locknut as the
damper rod may go into the damp-
er assembly and not be taken out.
REMOVING THE INNER TUBE
1. Remove:
• Dust seal "1"
• Stopper ring "2"
Using slotted-head screwdriver.
Take care not to scratch the inner
tube.
2. Remove:
• Inner tube "1"
Oil seal removal steps:
a. Push in slowly "a" the inner tube
just before it bottoms out and then
pull it back quickly "b".
b. Repeat this step until the inner
tube can be pulled out from the
outer tube.
REMOVING THE BASE VALVE
1. Remove:
• Base valve "1"
From damper assembly "2".
Hold the damper assembly with the
cap bolt ring wrench "3" and use the
cap bolt wrench "4" to remove the
base valve.
CHECKING THE DAMPER
ASSEMBLY
1. Inspect:
• Damper assembly "1"
Bend/damage
→ Replace.
• O-ring "2"
Wear/damage
→ Replace.
The front fork with a built-in piston
rod has a very sophisticated inter-
nal construction and is particularly
sensitive to foreign material.
Use enough care not to allow any
foreign material to come in when
the oil is replaced or when the
front fork is disassembled and re-
assembled.
CHECKING THE BASE VALVE
1. Inspect:
• Base valve "1"
Wear/damage
→Replace. Cap bolt ring wrench:
YM-01501/90890-01501
Cap bolt ring wrench:
YM-01501/90890-01501
Cap bolt wrench:
YM-01500/90890-01500
Cap bolt ring wrench:
YM-01501/90890-01501

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.

5-22
FRONT FORK
If the adjuster is installed out of spec-
ification, proper damping force can-
not be obtained.
29. Tighten:
• Adjuster (locknut) "1"
Hold the locknut "2" and tighten the
adjuster with specified torque.
30. Install:
• Adjuster "1"
To inner tube.
31. Fill:
• Front fork oil "1"
From outer tube top.
Never fail to make the oil amount
adjustment between the maximum
and minimum amount and always adjust each front fork to the same
setting. Uneven adjustment can
cause poor handling and loss of
stability.
• 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.
32. Install:
• Damper assembly "1"
To outer tube.
Temporarily tighten the damper as-
sembly.
33. Install:
• Protector guide "1"
INSTALLING THE FRONT FORK
1. Install:
• Front fork "1"
• Temporarily tighten the pinch bolts
(lower bracket).
• Do not tighten the pinch bolts (up-
per bracket) yet.
2. Tighten:
• Damper assembly "1"
Use the cap bolt ring wrench "2" to
tighten the damper assembly with
specified torque.
3. Adjust:
• Front fork top end "a"
4. Tighten:
• Pinch bolt (upper bracket) "1"
• Pinch bolt (lower bracket) "2"
Tighten the lower bracket to speci-
fied torque. If torqued too much, it
may cause the front fork to mal-
function.
Adjuster (locknut):
29 Nm (2.9 m•kg, 21
ft•lb)
Adjuster:
55 Nm (5.5 m•kg, 40
ft•lb)
Recommended oil:
Suspension oil "S1"
Standard oil amount:
350 cm
3 (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)
Damper assembly:
30 Nm (3.0 m•kg, 22
ft•lb)
Cap bolt ring wrench:
YM-01501/90890-01501
Front fork top end (stan-
dard) "a":
5 mm (0.20 in)
Pinch bolt (upper brack-
et):
21 Nm (2.1 m•kg, 15
ft•lb)
Pinch bolt (lower brack-
et):
21 Nm (2.1 m•kg, 15
ft•lb)