2008 YAMAHA WR 450F low oil pressure

1-17
CLEANING AND STORAGE
CLEANING AND STORAGE
CLEANING
Frequent cleaning of your machine
will enhance its appearance, maintain
good overall performance, and ex-
tend the life of many components.
1. Before washing the machine,
block off the end of the exhaust
pipe to prevent water from enter-
ing. A plastic bag secured with a
rubber band may be used for this
purpose.
2. If the engine is excessively
greasy, apply some degreaser to
it with a paint brush. Do not apply
degreaser to the chain, sprockets,
or wheel axles.
3. Rinse the dirt and degreaser off
with a garden hose; use only
enough pressure to do the job.
Excessive hose pressure may
cause water seepage and contami-
nation of wheel bearings, front
forks, brakes and transmission
seals. Many expensive repair bills
have resulted from improper high
pressure detergent applications
such as those available in coin-op-
erated car washers.
4. After the majority of the dirt has
been hosed off, wash all surfaces
with warm water and a mild deter-
gent. Use an old toothbrush to
clean hard-to-reach places.
5. Rinse the machine off immediate-
ly with clean water, and dry all
surfaces with a soft towel or cloth.
6. Immediately after washing, re-
move excess water from the
chain with a paper towel and lubri-
cate the chain to prevent rust.
7. Clean the seat with a vinyl uphol-
stery cleaner to keep the cover
pliable and glossy.
8. Automotive wax may be applied
to all painted or chromed surfac-
es. Avoid combination cleaner-
waxes, as they may contain abra-
sives.
9. After completing the above, start
the engine and allow it to idle for
several minutes.STORAGE
If your machine is to be stored for 60
days or more, some preventive mea-
sures must be taken to avoid deterio-
ration. After cleaning the machine
thoroughly, prepare it for storage as
follows:
1. Drain the fuel tank, fuel lines, and
the carburetor float bowl.
2. Remove the spark plug, pour a ta-
blespoon of SAE 10W-30 motor
oil in the spark plug hole, and re-
install the plug. With the engine
stop switch pushed in, kick the en-
gine over several times to coat the
cylinder walls with oil.
3. Remove the drive chain, clean it
thoroughly with solvent, and lubri-
cate it. Reinstall the chain or store
it in a plastic bag tied to the frame.
4. Lubricate all control cables.
5. Block the frame up to raise the
wheels off the ground.
6. Tie a plastic bag over the exhaust
pipe outlet to prevent moisture
from entering.
7. If the machine is to be stored in a
humid or salt-air environment,
coat all exposed metal surfaces
with a film of light oil. Do not apply
oil to rubber parts or the seat cov-
er.
Make any necessary repairs before
the machine is stored.

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

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)

3-13
ENGINE
• 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:
• Engine guard "1"
• Oil tank plug "2"
• Oil filler cap "3"
• Drain bolt (with gasket) "4"
• Oil filter drain bolt (O-ring) "5"
• Drain bolt (with gasket) "6"
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.
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 "1"
8. Inspect:
• Engine (for oil leaks)
• Oil level
Refer to "CHECKING THE EN-
GINE OIL LEVEL".
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.
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)

3-20
CHASSIS
3. Inspect:
• Brake fluid level
Refer to "CHECKING THE
BRAKE FLUID LEVEL" section.
4. Check:
• Brake pedal operation
A softy or spongy feeling→Bleed
brake system.
Refer to "BLEEDING THE HY-
DRAULIC BRAKE SYSTEM" sec-
tion.
CHECKING THE REAR BRAKE
PAD INSULATOR
1. Remove:
• Brake pad
Refer to "CHECKING AND RE-
PLACING THE REAR BRAKE
PADS" section.
2. Inspect:
• Rear brake pad insulator "1"
Damage→Replace.
CHECKING THE BRAKE FLUID
LEVEL
1. Place the brake master cylinder
so that its top is in a horizontal po-
sition.
2. Inspect:
• Brake fluid level
Fluid at lower level→Fill up.
• Use only designated quality
brake fluid to avoid poor brake
performance.
• Refill with same type and brand
of brake fluid; mixing fluids
could result in poor brake perfor-
mance.
• Be sure that water or other con-
taminants do not enter master
cylinder when refilling.
• Clean up spilled fluid immediate-
ly to avoid erosion of painted
surfaces or plastic parts.
a. Lower level
A. Front
B. Rear
CHECKING THE SPROCKET
1. Inspect:
• Sprocket teeth "a"
Excessive wear→Replace.
Replace the drive sprocket, rear
wheel sprocket and drive chain as a
set.
CHECKING THE DRIVE CHAIN
1. Measure:
• Drive chain length (15 links) "a"
Out of specification→Replace.
• While measuring the drive chain
length, push down on the drive
chain to increase its tension.
• Measure the length between drive
chain roller "1" and "16" as shown.
• Perform this measurement at two or
three different places.
2. Remove:
• Drive chain "1"
Remove the drive chain using a drive
chain cutter "2".
3. Clean:
• Drive chain
Brush off as much dirt as possi-
ble. Then clean the drive chain
using the chain cleaner.
This machine has a drive chain
with small rubber O-rings "1" be-
tween the side plates. Steam
cleaning, high-pressure washes,
certain solvent and kerosene can
damage these O-rings.
4. Inspect:
• O-ring "1" (drive chain)
Damage→Replace the drive
chain.
•Roller "2"
• Side plate "3"
Damage/wear→Replace the
drive chain.
5. Check:
• Drive chain stiffness "a"
Clean and oil the drive chain and
hold as illustrated.
Stiff→Replace the drive chain.
6. Install:
• Chain joint "1"
• O-ring "2"
• Drive chain "3"
• Link plate "4" Recommended brake flu-
id:
DOT #4
Drive chain length (15
links):
: 239.3 mm
(9.42 in)

4-5
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 level.
2. Setting of spring preload
• Change the spring.
• Install the adjustment washer.
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 LEVEL AND
CHARACTERISTICS OF FORK OIL
Damping characteristic near the final
stroke can be changed by changing
the fork oil amount.
Adjust the oil level in 5 mm (0.2 in)
increments or decrements. Too
low oil level causes the front fork
to produce a noise at full rebound
or the rider to feel some pressure
on his hands or body. Alternative-
ly, too high oil level will develop
unexpectedly early oil lock with
the consequent shorter front fork
travel and deteriorated perfor-
mance and characteristics. There-
fore, adjust the front fork within
the specified range.
Secondary reduction ratio =
Number of rear wheel sprocket
teeth/Number of drive sprocket
teeth
Standard secondary
reduction ratio50/13
(3.846)
* 47/14
(3.357)
* For EUROPE
Part
nameSize Part number
Drive
sprocket
"1"
(STD) 13T 9383E-13233
* 14T 9383E-14215
** (STD) ** 14T 5NG-17460-00
* For AUS and NZ
** For EUROPE
Part
nameSize Part number
Rear
wheel
sprocket
"2"
** (STD) ** 47T 1C3-25447-00
48T 5GS-25448-50
* 48T 1C3-25448-00
* 49T 1C3-25449-00
(STD) 50T 5TJ-25450-80
* (STD) * 50T 1C3-25450-00
* 51T 1C3-25451-00
52T 5TJ-25452-80
* 52T 1C3-25452-00
* For AUS and NZ
** For EUROPE
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)

6-38
REAR SHOCK ABSORBER
HANDLING NOTE
• Support the machine securely so
there is no danger of it falling
over.
• This rear shock absorber is pro-
vided with a separate type tank
filled with high-pressure nitro-
gen gas. To prevent the danger
of explosion, read and under-
stand the following information
before handling the shock ab-
sorber. The manufacturer can
not be held responsible for prop-
erty damage or personal injury
that may result from improper
handling.
• Never tamper or attempt to dis-
assemble the cylinder or the
tank.
• Never throw the rear shock ab-
sorber into an open flame or
other high heat. The rear shock
absorber may explode as a re-
sult of nitrogen gas expansion
and/ or damage to the hose.
• Be careful not to damage any
part of the gas tank. A damaged
gas tank will impair the damp-
ing performance or cause a
malfunction.
• Take care not to scratch the
contact surface of the piston
rod with the cylinder; or oil
could leak out.
• Never attempt to remove the
plug at the bottom of the nitro-
gen gas tank. It is very danger-
ous to remove the plug.
• When scrapping the rear shock
absorber, follow the instruc-
tions on disposal.
NOTES ON DISPOSAL (YAMAHA
DEALERS ONLY)
Before disposing the rear shock ab-
sorber, be sure to extract the nitrogen
gas from valve "1". Wear eye protec-
tion to prevent eye damage from es-
caping gas and/or metal chips.
To dispose of a damaged or worn-
out rear shock absorber, take the
unit to your Yamaha dealer for this
disposal procedure.
REMOVING THE BEARING
1. Remove:
• Stopper ring (upper bearing) "1"
Press in the bearing while pressing its
outer race and remove the stopper
ring.
2. Remove:
• Upper bearing "1"
Remove the bearing by pressing its
outer race.
3. Remove:
• Lower bearing "1"
Remove the bearing by pressing its
outer race.
CHECKING THE REAR SHOCK
ABSORBER
1. Inspect:
• Damper rod "1"
Bends/damage→Replace rear
shock absorber assembly.
• Shock absorber "2"
Oil leaks→Replace rear shock
absorber assembly.
Gas leaks→Replace rear shock
absorber assembly.• Spring "3"
Damage→Replace spring.
Fatigue→Replace spring.
Move spring up and down.
• Spring guide "4"
Wear/damage→Replace spring
guide.
• Bearing "5"
Free play exists/unsmooth revolu-
tion/rust →Replace.
INSTALLING THE BEARING
1. Install:
• Upper bearing "1"
Install the bearing parallel until the
stopper ring groove appears by
pressing its outer race.
Do not apply the grease on the
bearing outer race because it will
wear the rear shock absorber sur-
face on which the bearing is press
fitted.
2. Install:
• Stopper ring (upper bearing) "1"
After installing the stopper ring, push
back the bearing until it contacts the
stopper ring.