YAMAHA YFZ450 2008 Workshop Manual

5-6
1
2
3
45
6
7
8
9
10
11

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.
EBU19820
Measuring the tire pressure
Use the low-pressure tire gauge.
NOTE:

The low-pressure tire gauge is included as stan-

5-7
1
2
3
45
6
7
8
9
10
11

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:
EBU19830
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
)

5-8
1
2
3
45
6
7
8
9
10
11

EBU19840
Chassis fasteners
Make sure that all nuts, bolts and screws are prop-
erly tightened.
EBU19850
Instruments, lights and switches
Check that all instruments, lights and switches are
working properly. Correct if necessary.
1. Tire wear limit

6-1
1
2
3
4
56
7
8
9
10
11

EBU19880
OPERATION
EBU19900
Read the Owner’s Manual carefully before riding
the ATV.
WARNING

EWB00630
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.
EBU20101
Starting a cold engine
WARNING

EWB00640
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:

6-2
1
2
3
4
56
7
8
9
10
11

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)
1
23
123
4

6-3
1
2
3
4
56
7
8
9
10
11

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.
EBU20291
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.
EBU20520
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.
EBU20570
To start out and accelerate
1. Release the throttle lever.
1. Shift pedal
2. Neutral position
1
2

6-4
1
2
3
4
56
7
8
9
10
11
CAUTION:

ECB00200
Always close the throttle before shifting gears,
otherwise damage to the engine and drive train
may result.
2. Pull the clutch lever to disengage the clutch.
3. Shift into first gear.
4. Open the throttle gradually and at the same
time, release the clutch lever slowly.
5. Once the ATV has attained adequate speed,
release the throttle, and at the same time,
quickly pull in the clutch lever.
6. Shift the transmission into second gear.
(Make sure not to shift the transmission into
neutral)
7. Open the throttle part way and gradually re-
lease the clutch lever.
8. Follow the same procedure when shifting to
the next higher gear.
WARNING

EWB00730
Opening the throttle abruptly or releasing the
clutch lever too quickly could make the ATV
wheelie, which would increase the chance of
an accident, including an overturn.
EBU20650
To decelerate
When slowing down or stopping, release the throt-
tle and apply the brakes smoothly and evenly. As
you slow down, shift to a lower gear. Be sure that
the engine has sufficiently slowed before engaging
a lower gear. Improper use of the brakes or shifting
can cause the tires to lose traction, reducing con-
trol and increasing the possibility of an accident.WARNING
EWB00710
Make sure the engine has sufficiently slowed
before shifting to a lower gear. Engaging a low-
er gear when the engine speed is too high
could make the wheels stop rotating and lose
traction. This could cause loss of control, an
accident and injury. It could also cause engine
or drive train damage.
CAUTION:

ECB00180

Even with the transmission in the neutral po-
sition, do not coast for long periods of time
with the engine off, and do not tow the ATV
for long distances. The transmission is prop-
erly lubricated only when the engine is run-
ning. Inadequate lubrication may damage

6-5
1
2
3
4
56
7
8
9
10
11

the transmission.

Always use the clutch when changing gears.
The engine, transmission and drive train are
not designed to withstand the shock of
forced shifting and can be damaged by shift-
ing without using the clutch.
EBU20670
Engine break-in
There is never a more important period in the life of
your engine than the first 20 hours of riding. For
this reason, you should read the following material
carefully.
Since the engine is brand new, do not put an ex-
cessive load on it for the first 20 hours. The various
parts in the engine wear and polish themselves to
the correct operating clearances. During this peri-
od, prolonged full-throttle operation or any condi-
tion that might result in engine overheating must
be avoided.
0–10 hours
Avoid prolonged operation above 1/2 throttle. Vary
the speed of the ATV regularly. Do not operate it at
one set throttle position.
10–20 hours
Avoid prolonged operation above 3/4 throttle. Rev
the engine through the gears freely, but do not use
full throttle at any time.
20 hours and beyond
The ATV can now be operated normally.CAUTION:

ECB00220
If any engine trouble should occur during the
engine break-in period, immediately have a
Yamaha dealer check the ATV.
EBU20721
Parking
When parking the ATV, stop the engine, shift into
first gear, apply the parking brake, and then turn
the fuel cock to “OFF”.

6-6
1
2
3
4
56
7
8
9
10
11

EBU20860
Parking on a slope
WARNING

EWB00850
Avoid parking on hills or other inclines. Park-
ing on a hill or other incline could cause the
ATV to roll out of control, increasing the
chance of an accident. If you must park on an
incline, place the ATV transversely across the
incline, shift into first gear, stop the engine, ap-
ply the parking brake, and then block the front
and rear wheels with rocks or other objects.
Do not park the ATV at all on hills that are so
steep you could not walk up them easily.
1. Bring the ATV to a stop by applying the brakes
in first gear.
2. Stop the engine and release the clutch lever.
3. With the rear brake applied, apply the parking
brake and slowly release the brake pedal.
EBU20910
Accessories and loading
EBU20920
Accessories
Accessories can affect the handling and control of
your ATV. Keep the following in mind when consid-
ering an accessory or operating an ATV which has
accessories.
1. Locked position
1

6-7
1
2
3
4
56
7
8
9
10
11


Choose only accessories designed for your
ATV. Your Yamaha dealer has a variety of gen-
uine Yamaha accessories. Other accessories
may also be available on the market. However,
it is not possible for Yamaha to test all non-
Yamaha accessories, nor control over their qual-
ity or suitability. Choose a genuine Yamaha ac-
cessory, or one that is equivalent in design and
quality.

Accessories should be rigidly and securely
mounted. An accessory which can shift position
or come off while you are riding could affect your
ability to control the ATV.

Do not mount an accessory where it could inter-
fere with your ability to control the ATV. Exam-
ples include (but are not limited to) a heavy or
bulky object attached to the handlebars which
could make steering difficult, an accessory that
limits your ability to move around on the seat, or
one that limits your view.

Use extra caution when riding an ATV with ac-
cessories. The ATV may handle differently than
it does without accessories.
EBU20940
Loading
As originally equipped, this ATV is not designed to
carry cargo or tow a trailer. If you choose to add ac-
cessories so that you can carry cargo or tow a trail-
er, you must use common sense and good
judgment as the stability and handling of an ATV
can be changed. When adding accessories, keep
the following points in mind:

Never exceed the weight limits shown. An over-
loaded ATV can be unstable.

If you are carrying cargo and towing a trailer, in-
clude the tongue weight in the maximum ATV
load limit.

Load cargo on the carriers as close to the center
of the ATV as possible. Put cargo at the rear of
the front carrier, at the front of the rear carrier,
and center it.

Tie down cargo securely to the carriers. Make
sure cargo in the trailer cannot move around. A
shifting load can cause an accident. MAXIMUM LOADING LIMIT
ATV loading limit (total weight of rider, cargo,
accessories, and tongue):
100.0 kg (220 lb)