2008 YAMAHA YFZ450 Owners Manual

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Fuel
Make sure that there is sufficient fuel in the tank.
(See page 4-8.)
WARNING

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Do not overfill the fuel tank. Fuel expands
when it heats up. If the fuel tank is overfilled,
fuel could spill out due to heat from the en-
gine or the sun.

Be careful not to spill fuel, especially on the
engine or exhaust pipe which can cause a
fire and severe injury. Wipe up any spilled
fuel immediately.

Do not refuel right after the engine has been
running and is still very hot.

Be sure the fuel tank cap is closed securely.
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Engine oil
Make sure that the engine oil is at the specified lev-
el. Add oil as necessary.
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Coolant
Make sure that the coolant is at the specified level.
Add coolant as necessary. (See page 8-20.)
NOTE:

The coolant level must be checked on a cold en-
gine since the level varies with engine tempera-
ture.
WARNING

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Wait for the engine and radiator to cool before
removing the radiator cap. You could be
burned by hot fluid and steam blown out under
pressure. Always put a thick rag over the cap
when opening. Allow any remaining pressure
to escape before completely removing the cap.
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Front and rear brakes
Brake lever and brake pedal

Check that there is no free play in the brake le-
ver. If there is free play, have a Yamaha dealer
check the brake system.

Check for correct brake pedal height. (See
page 8-36.) If the pedal height is incorrect, have
a Yamaha dealer adjust it.

Check the operation of the lever and pedal. They
should move smoothly and there should be a
firm feeling when the brakes are applied. If not,

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have a Yamaha dealer check the brake system.
Brake fluid level
Check the brake fluid level. Add fluid if necessary.
(See page 8-32.)
Brake fluid leakage
Check to see if any brake fluid is leaking out of the
pipe joints or brake fluid reservoirs. Apply the
brakes firmly for one minute. If there is any leak-
age, have a Yamaha dealer check the brake sys-
tem.
Brake operation
Test the brakes at slow speed after starting out to
make sure they are working properly. If the brakes
do not provide proper braking performance, check
the brake pads for wear. (See page 8-31.)
WARNING

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Always check the brakes at the start of every
ride. Do not ride the ATV if you find any prob-
lem with the brakes or you could lose braking
ability, which could lead to an accident. If aproblem cannot be corrected by the adjust-
ment procedures provided in this manual, have
a Yamaha dealer check for the cause.
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Throttle lever
Check the operation of the throttle lever. It must
open smoothly and spring back to the idle position
when released. Have a Yamaha dealer correct if
necessary.
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Drive chain
Check the condition of the drive chain and check
the drive chain slack. Lubricate and adjust the
drive chain as necessary.
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Tires
WARNING

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Use of improper tires on this ATV, or operation
of this ATV with improper or uneven tire pres-
sure, may cause loss of control, increasing
your risk of accident.
Pay attention to the following.

The tires listed below have been approved
Recommended brake fluid:
DOT 4

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by Yamaha Motor Co., Ltd. for this model.
Other tire combinations are not recommend-
ed.
Front:
Manufacturer/model:
DUNLOP/KT341 Radial
Size:
AT21 x 7-10
Type:
Tubeless
Rear:
Manufacturer/model:
DUNLOP/KT355A Radial
Size:
AT20 x 10-9
Type:
Tubeless

The tires should be set to the recommended
pressure:
Recommended tire pressure:
Front:
27.5 kPa (4.0 psi) (0.275 kgf/cm
2
)
Rear:
30.0 kPa (4.4 psi) (0.300 kgf/cm
2
)

Check and adjust tire pressures when the
tires are cold.

Tire pressures must be equal on both
sides.

Tire pressure below the minimum speci-
fied could cause the tire to dislodge from
the rim under severe riding conditions.
Minimum tire pressure:
Front:
24.5 kPa (3.5 psi) (0.245 kgf/cm
2
)
Rear:
27.0 kPa (3.9 psi) (0.270 kgf/cm
2
)

Use no more than the following pressures
when seating the tire beads.
Maximum tire seating pressure:
Front:
250 kPa (36 psi) (2.5 kgf/cm
2
)
Rear:
250 kPa (36 psi) (2.5 kgf/cm
2
)
Higher pressures and fast inflation may
cause a tire to burst. Inflate the tires very
slowly and carefully.
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Measuring the tire pressure
Use the low-pressure tire gauge.
NOTE:

The low-pressure tire gauge is included as stan-

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dard equipment. Make two measurements of the
tire pressure and use the second reading. Dust or
dirt in the gauge could cause the first reading to be
incorrect.
Set the tire pressure when the tires are cold. Set
the tire pressures to the following specifications:
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Tire wear limit
Replace the tire when the tire groove decreases to
3 mm (0.12 in).
1. Low-pressure tire gauge
Recommended pressure:
Front
27.5 kPa (4.0 psi) (0.275 kgf/cm
2
)
Rear
30.0 kPa (4.4 psi) (0.300 kgf/cm
2
)
Minimum:
Front
24.5 kPa (3.5 psi) (0.245 kgf/cm
2
)
Rear
27.0 kPa (3.9 psi) (0.270 kgf/cm
2
)
Maximum:
Front
30.5 kPa (4.4 psi) (0.305 kgf/cm
2
)
Rear
33.0 kPa (4.8 psi) (0.330 kgf/cm
2
)

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Chassis fasteners
Make sure that all nuts, bolts and screws are prop-
erly tightened.
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Instruments, lights and switches
Check that all instruments, lights and switches are
working properly. Correct if necessary.
1. Tire wear limit

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OPERATION
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Read the Owner’s Manual carefully before riding
the ATV.
WARNING

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Read the Owner’s Manual carefully to become
familiar with all controls in order to help pre-
vent any loss of control, which could cause an
accident or injury. If there is a control or func-
tion you do not understand, ask your Yamaha
dealer.
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Starting a cold engine
WARNING

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Always make sure all control cables work
smoothly before you begin riding in cold
weather. If the control cables are frozen or do
not work smoothly, you could be unable to
control the ATV, which could lead to an acci-
dent or collision.
CAUTION:

ECB00150
See the “Engine break-in” section on page 6-5
prior to operating the engine for the first time.
1. Set the parking brake.
2. Turn the fuel cock to “ON”.
3. Turn the main switch to “ON” and the engine
stop switch to “RUN”.
4. Shift the transmission into neutral. The neutral
indicator light should come on. If the indicator
light does not come on, have a Yamaha deal-
er check the electrical circuit.
NOTE:

This model is equipped with an ignition circuit cut-
off system. The engine can be started under the
following conditions.

The transmission is in neutral.

The clutch is disengaged with the transmission
in gear. However, it is recommended to shift into
neutral before starting the engine.
5. Use the starter (choke) in reference to the fig-
ure:

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Position (1):

Cold engine start with ambient temperature be-
low 5 °C (40 °F).
Position (2):

Cold engine start with ambient temperature be-
tween 0 °C (30 °F) and 30 °C (90 °F).
Position (3):

Cold engine start with ambient temperature
above 25 °C (80 °F).
Ambient temp./starter (choke) position
6. Completely close the throttle lever and start
the engine by pushing the start switch.
NOTE:

If the engine fails to start, release the start switch,
then push it again. Pause a few seconds before
the next attempt. Each cranking should be as short
as possible to preserve battery energy. Do not
crank the engine more than 10 seconds on each
1. Fully open
2. Half open
3. Closed
4. Starter (choke)
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attempt.
7. If the engine is started with the starter (choke)
in position (1), the starter (choke) should be
returned to position (2) to warm up the engine.
If the engine is started with the starter (choke)
in position (2), keep the starter (choke) in this
position to warm up the engine.
CAUTION:

ECB00160
For maximum engine life, always warm the en-
gine up before starting off. Never accelerate
hard when the engine is cold!
8. Continue warming up the engine until it idles
smoothly, then return the starter (choke) to
position (3) before riding.
NOTE:

The engine is warm when it responds normally to
the throttle with the starter (choke) turned off.
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Starting a warm engine
Follow the same procedure as for starting a cold
engine, with the exception that the starter (choke)
is not required when the engine is warm. Instead,
start the engine with the throttle slightly open.
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Shifting
This ATV has a 5-speed forward transmission. The
transmission allows you to control the amount of
power you have available at a given speed or for
starting, accelerating, climbing hills, etc.
To shift into neutral, return the throttle lever to the
closed position, apply the clutch, and then repeat-
edly depress the shift pedal until it stops.
When it stops, it will be in first gear. Raise the pedal
slightly to reach the neutral position.
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To start out and accelerate
1. Release the throttle lever.
1. Shift pedal
2. Neutral position
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