engine YAMAHA YFZ450R 2009 User Guide
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turned off for an extended period of time, oth-
erwise the battery may discharge to the point
that the starter motor will not operate properly.
If this should happen, remove the battery and
recharge it.
EBU18280
Throttle lever
Once the engine is running, movement of the throt-
tle lever will increase the engine speed.
Regulate the speed of the ATV by varying the
throttle position. Because the throttle is spring-
loaded, the ATV will decelerate, and the engine will
return to an idle any time the hand is removed from
the throttle lever.Before starting the engine, check the throttle to be
sure it is operating smoothly. Make sure it returns
to the idle position as soon as the lever is released.
WARNING
EWB00250
Malfunction of the throttle could make it diffi-
cult to speed up or slow down when you need
to. This could cause an accident. Check the op-
eration of the throttle lever before you start the
engine. If the throttle does not work smoothly,
check for the cause. Correct the problem be-
fore riding the ATV or consult a Yamaha dealer.
1. Throttle lever
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EBU18321
Speed limiter
Your ATV was delivered with an adjustable speed
limiter. The speed limiter keeps the throttle from
fully opening, even when the throttle lever is
pushed to the maximum.
1. Loosen the locknut.
2. To increase the maximum engine power avail-
able and the maximum speed of the ATV, turn
the adjusting screw in direction (a). To de-
crease the maximum engine power available
and the maximum speed of the ATV, turn the
adjusting screw in direction (b).
3. Tighten the locknut.
WARNING
EWB00240
Improper adjustment of the speed limiter and
throttle could cause throttle cable damage or
improper throttle operation. You could lose
control, have an accident or be injured. Do not
turn the adjusting screw out more than 12 mm
(0.47 in) or the throttle cable could be dam-
aged. Always make sure the throttle lever free
play is adjusted to 2.0–4.0 mm (0.08–0.16 in).
(See page 8-28.)
1. Locknut
2. Adjusting screw
3. No more than 12 mm (0.47 in)
3
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2
(a)
(b)
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Brake pedal
The brake pedal is located on the right side of the
ATV. To apply the rear brake, push down on the
brake pedal.
EBU18520
Parking brake lever
Use the parking brake before starting the engine or
parking the ATV, especially on a slope. To apply
the parking brake, move the parking brake lever in
direction (a). To release the parking brake, move
the parking brake lever in direction (b).
1. Brake pedal
1
1. Parking brake lever (locked position)
1. Parking brake lever (unlocked position)
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WARNING
EWB00220
Always set the parking brake before starting
the engine. The ATV could start moving un-
expectedly if the parking brake is not ap-
plied. This could cause loss of control or a
collision.
Always be sure you have released the park-
ing brake before you begin to ride. The brake
could overheat if you ride the ATV without re-
leasing the parking brake. You could lose
braking performance which could cause an
accident. You could also wear out the brakes
prematurely.
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Shift pedal
This ATV is equipped with a constant-mesh 5-
speed transmission. The shift pedal is located on
the left side of the engine and is used in combina-
tion with the clutch when shifting.
EBU18720
Fuel tank cap
Remove the fuel tank cap by turning it counter-
clockwise.
1. Shift pedal
1
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TIP
If knocking or pinging occurs, use a different brand
of gasoline or higher octane grade.
NOTICE
ECB00070
Use only unleaded gasoline. The use of leaded
gasoline will cause severe damage to internal
engine parts, such as the valves and piston
rings, as well as to the exhaust system.
WARNING
EWB00310
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.
EBU18890
Seat
To remove the seat
Insert your hand between the rear of the seat and
the rear fender, pull the seat lock lever upward and
pull up the seat at the rear.
To install the seat
Insert the projections on the front of the seat into
the seat holders and push down on the seat at the
rear.
1. Seat lock lever
1
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EBU19200
PRE-OPERATION CHECKS
EBU19223
Pre-operation check list
Before operating this ATV, be sure to check the items listed in the following table.
WARNING
EWB00480
Always inspect your ATV each time you use it to make sure it is in safe operating condition.
Always follow the inspection and maintenance procedures and schedules described in the Owner’s
Manual. Failure to inspect increases the possibility of an accident or equipment damage.
TIP
The maintenance of some items in the table has to be performed by a Yamaha dealer. Refer to the periodic
maintenance charts on page 8-3 to determine which service should be performed by a Yamaha dealer.
ITEM ROUTINE PAGE
Fuel
Check fuel level in fuel tank, and add recommended fuel if neces-
sary.
Check fuel line for leakage. Correct if necessary.4-9, 5-4
Engine oil
Check oil level in engine, and add recommended oil to specified
level if necessary.
Check ATV for oil leakage. Correct if necessary.5-4, 8-14
Coolant
Check coolant level in reservoir, and add recommended coolant to
specified level if necessary.
Check cooling system for leakage. Correct if necessary.5-4, 8-19
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EBU19540
Fuel
Make sure that there is sufficient fuel in the tank.
(See page 4-9.)
WARNING
EWB00520
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.
EBU19560
Engine oil
Make sure that the engine oil is at the specified lev-
el. Add oil as necessary. (See page 8-14.)
EBU19630
Coolant
Make sure that the coolant is at the specified level.
Add coolant as necessary. (See page 8-19.)
TIP
The coolant level must be checked on a cold en-
gine since the level varies with engine tempera-
ture.
WARNING
EWB00510
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.
EBU19710
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 8-33.) 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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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.
EBU29482
Starting the 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.NOTICE
ECB00150
See the “Engine break-in” section on page 6-4
prior to operating the engine for the first time.
1. Set the parking brake.
2. Turn the key to “ON” and the engine stop
switch to “ ”.
NOTICE
ECB00950
The coolant temperature warning light, fuel
level warning light and engine trouble warning
light should come on, then go off.
If a warning light does not go off, see page 4-2
for the corresponding warning light circuit
check.
3. Shift the transmission into neutral. The neutral
indicator light should come on, if it does not
come on, have a Yamaha dealer check the
electrical circuit.
TIP
This model is equipped with an ignition circuit cut-
off system. The engine can be started under the
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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.
4. Completely close the throttle lever and start
the engine by pushing the start switch.
TIP
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
attempt.
NOTICE
ECB00161
For maximum engine life, never accelerate
hard when the engine is cold!
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.
EBU20590
To start out and accelerate
1. Release the throttle lever, and then release
the parking brake.
NOTICE
ECB00200
Always close the throttle before shifting gears,
1. Shift pedal
2. Neutral position
1 22 3
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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.NOTICE
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
the transmission.
Always use the clutch when changing gears.
The engine, transmission and drive train are