2005 YAMAHA YFZ450 engine

4-5
3. Push the start switch. If the warning light
does not come on while the start switch is
pushed, have a Yamaha dealer check the
electrical circuit.CAUTION:_

The engine may overheat if the ATV is
overloaded. If this happens, reduce the
load to specification.


Restart after making sure that the light is
off. Continuous use while the light is on
may cause damage to the engine.
_
U5TG61.book Page 5 Friday, April 2, 2004 11:28 AM

4-7 1. Light switch “LIGHTS”
2. Engine stop switch “ENG. STOP”
3. Start switch “START”
1. Contacteur d’éclairage “LIGHTS”
2. Coupe-circuit du moteur “ENG. STOP”
3. Contacteur du démarreur “START”
1. Interruptor de luces “LIGHTS”
2. Interruptor de parada del motor “ENG. STOP”
3. Interruptor de arranque “START”
EBU00530
Handlebar switches
EBU13741
Light switch “LIGHTS”
Set the switch to the “LO” position to turn on the
low beam and the taillight.
Set the switch to the “HI” position to turn on the
high beam and the taillight.
Set the switch to the “OFF” position to turn off all
the lights.NOTE:_ The headlights and the taillight can be turned on
only when the engine is started. _
EBU06470
Start switch “START”
The starter motor cranks the engine when this
switch is pushed.CAUTION:_ See the starting instructions on page 6-3 prior
to starting the engine. _
U5TG61.book Page 7 Friday, April 2, 2004 11:28 AM

4-9 1. Light switch “LIGHTS”
2. Engine stop switch “ENG. STOP”
3. Start switch “START”
1. Contacteur d’éclairage “LIGHTS”
2. Coupe-circuit du moteur “ENG. STOP”
3. Contacteur du démarreur “START”
1. Interruptor de luces “LIGHTS”
2. Interruptor de parada del motor “ENG. STOP”
3. Interruptor de arranque “START”
EBU11580
Engine stop switch “ENG. STOP”
Make sure that the engine stop switch is in the
“RUN” position before starting the engine. The en-
gine stop switch controls ignition and can be used
at all times to stop the engine, especially in an
emergency. The engine will not start or run when
the engine stop switch is turned to “OFF”.
U5TG61.book Page 9 Friday, April 2, 2004 11:28 AM

4-11 1. Throttle lever
1. Levier d’accélération
1. Palanca de aceleración
EBU00630
Throttle lever
Once the engine is running, movement of the
throttle lever will increase the engine speed.
Regulate the speed of the machine by varying the
throttle position. Because the throttle is spring-
loaded, the machine will decelerate, and the en-
gine will return to an idle any time the hand is re-
moved 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
_ 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
operation of the throttle lever before you start
the engine. If the throttle does not work
smoothly, check for the cause. Correct the
problem before riding the ATV or consult a
Yamaha dealer. _
U5TG61.book Page 11 Friday, April 2, 2004 11:28 AM

4-13 1. Locknut 2. Adjusting screw
a. No more than 12 mm
1. Contre-écrou 2. Vis de réglage
a. 12 mm maximum
1. Contratuerca 2. Tornillo de ajuste
a. 12 mm como máximo
EBU11980
Speed limiter
The speed limiter keeps the throttle from fully
opening, even when the throttle lever is pushed to
the maximum. Turning in the adjusting screw limits
the maximum engine power available and de-
creases the maximum speed of the ATV.
WARNING
_ 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
or the throttle cable could be damaged. Always
make sure the throttle lever free play is adjust-
ed to 2–4 mm. See page 8-77. _
U5TG61.book Page 13 Friday, April 2, 2004 11:28 AM

4-15 1. Clutch lever
1. Levier d’embrayage
1. Palanca de embrague
EBU00690
Clutch lever
The clutch lever is located on the left handlebar
and the ignition circuit cut-off system is incorporat-
ed in the clutch lever holder. Pull the clutch lever to
the handlebar to disengage the clutch, and release
the lever to engage the clutch. The lever should be
pulled rapidly and released slowly for smooth
clutch operation. (Refer to “Starting a cold engine”
for a description of the ignition circuit cut-off sys-
tem.)
U5TG61.book Page 15 Friday, April 2, 2004 11:28 AM

4-19 1. Parking brake lever (Locked position)
1. Levier de frein de stationnement (frein serré)
1. Palanca del freno de estacionamiento (posición de bloqueo)
1. Parking brake lever (Unlocked position)
1. Levier de frein de stationnement (frein relâché)
1. Palanca del freno de estacionamiento
(posición de desbloqueo)
EBU14072
Parking brake lever
Use the parking brake when you have to start the
engine or park the machine, 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.
WARNING
_

Always set the parking brake before start-
ing the engine. The ATV could start mov-
ing unexpectedly if the parking brake is not
applied. This could cause loss of control or
a collision.


Always be sure you have released the
parking brake before you begin to ride. The
brake could overheat if you ride the ATV
without releasing the parking brake. You
could lose braking performance which
could cause an accident. You could also
wear out the brakes prematurely.
_
U5TG61.book Page 19 Friday, April 2, 2004 11:28 AM

4-21 1. Shift pedal
1. Pédale de sélection
1. Pedal del cambio
1. Fuel tank cap
1. Bouchon du réservoir de carburant
1. Tapón del depósito de combustible
EBU00820
Shift pedal
This machine 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 combi-
nation with the clutch when shifting.
EBU00920
Fuel tank cap
Remove the fuel tank cap by turning it counter-
clockwise.
U5TG61.book Page 21 Friday, April 2, 2004 11:28 AM