2007 YAMAHA YFZ450 engine

4-3
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34
5
6
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EBU18060
Handlebar switches
EBU18070
Engine stop switch “ENG. STOP”
Set this switch to “RUN” before starting the engine.
The engine stop switch controls the ignition and
stops the engine when it is running. Use this switch
to stop the engine in an emergency situation. The
engine will not start or run when this switch is set
to “OFF”.
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Start switch “START”
Push this switch to crank the engine with the start-
er.CAUTION:

ECB00050
See the starting instructions on page 6-1 prior
to starting the engine.
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Light switch “LIGHTS”
Set this switch to “LO” to turn on the low beams
and the taillight. Set the switch to “HI” to turn on the
high beams and the taillight. Set the switch to
“OFF” to turn off all the lights.
NOTE:

The headlights and the taillight can be turned on
only when the engine is running.
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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
1. Light switch “LIGHTS”
2. Engine stop switch “ENG. STOP”
3. Start switch “START”
1
2
3

4-4
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34
5
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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.
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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).
1. Throttle lever

4-6
1
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34
5
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11

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Brake lever
The brake lever is located at the right handlebar
grip. To apply the front brake, pull the brake lever
toward the handlebar grip.
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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.
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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 lever
2. Locknut
3. Brake lever position adjusting bolt
4. Distance between brake lever and handlebar grip
1
4
23

1. Brake pedal
1

4-7
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34
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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.
1. Parking brake lever (locked position)
1. Parking brake lever (unlocked position)

4-9
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34
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NOTE:

If knocking or pinging occurs, use a different brand
of gasoline or higher octane grade.CAUTION:
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.
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Fuel cock
The fuel cock supplies fuel from the tank to the car-
buretor while also filtering it.
1. Fuel level
2. Filler tube
Recommended fuel:
PREMIUM UNLEADED GASOLINE ONLY
For Europe: PREMIUM UNLEADED GASO-
LINE ONLY with a research octane number
of 97 or higher
Fuel tank capacity:
10.0 L (2.64 US gal) (2.20 Imp.gal)
Fuel reserve amount:
1.9 L (0.50 US gal) (0.42 Imp.gal)

4-10
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The fuel cock lever positions are explained as fol-
lows and shown in the illustrations.
OFF
With the fuel cock lever in this position, fuel will not
flow. Always turn the fuel cock lever to this position
when the engine is not running.
ON
With the fuel cock lever in this position, fuel flows
to the carburetor. Turn the fuel cock lever to this
position when starting the engine and riding.

1. Arrow mark positioned over “OFF”
1. Arrow mark positioned over “ON”

4-11
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RES
This indicates reserve. With the fuel cock lever in
this position, the fuel reserve is made available.
Turn the fuel cock lever to this position if you run
out of fuel while riding. When this occurs, refuel as
soon as possible and be sure to turn the fuel cock
lever back to “ON”!
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Starter (choke) “”
Starting a cold engine requires a richer air-fuel mix-
ture, which is supplied by the starter (choke).
Move the starter (choke) in direction (a) to turn onthe starter (choke).
Move the starter (choke) in direction (b) to turn off
the starter (choke).
See the “Starting a cold engine” section on page
6-1 for proper operation.
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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.
1. Arrow mark positioned over “RES”
1. Starter (choke) “ ”
1
(a)(b)

5-1
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PRE-OPERATION CHECKS
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Pre-operation check list
Before operating this ATV, be sure to check the items listed in the following table.
NOTE:

The maintenance of some items in the table has to be performed by a Yamaha dealer. Refer to the “Periodic
maintenance and lubrication chart” 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.4-8, 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, 8-13
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
Front brake

Check operation. If soft or spongy, have Yamaha dealer bleed
hydraulic system.

Check brake pads for wear, and replace if necessary.

Check brake fluid level in reservoir, and add recommended brake
fluid to specified level if necessary.

Check hydraulic system for leakage. Correct if necessary.5-4, 8-30, 8-31, 8-34