engine YAMAHA WR 450F 2004 User Guide

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GEN
INFO
IMPORTANT INFORMATION
EC132000
ALL REPLACEMENT PARTS
1. We recommend to use Yamaha genuine
parts for all replacements. Use oil and/or
grease recommended by Yamaha for
assembly and adjustment.
EC133000
GASKETS, OIL SEALS AND O-RINGS
1. All gaskets, oil seals, and O-rings should
be replaced when an engine is over-
hauled. All gasket surfaces, oil seal lips,
and O-rings must be cleaned.
2. Properly oil all mating parts and bearings
during reassembly. Apply grease to the
oil seal lips.
EC134000
LOCK WASHERS/PLATES AND COTTER
PINS
1. All lock washers/plates 1 and cotter pins
must be replaced when they are
removed. Lock tab(s) should be bent
along the bolt or nut flat(s) after the bolt
or nut has been properly tightened.
EC135001
BEARINGS AND OIL SEALS
1. Install the bearing(s) 1 and oil seal(s) 2
with their manufacturer’s marks or num-
bers facing outward. (In other words, the
stamped letters must be on the side
exposed to view.) When installing oil
seal(s), apply a light coating of light-
weight lithium base grease to the seal
lip(s). Oil the bearings liberally when
installing.
CAUTION:
Do not use compressed air to spin the
bearings dry. This causes damage to the
bearing surfaces.

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GEN
INFO
CONTROL FUNCTIONS
EC150000
CONTROL FUNCTIONS
MAIN SWITCH
Functions of the respective switch positions
are as follows:
ON:
The engine can be started only at this position.
OFF:
All electrical circuits are switched off.
Main switch indicator light
The main switch 1 is equipped with an indica-
tor light 2 to avoid forgetting to turn it off. This
light functions as follows.
It lights up with the main switch “ON”.
It goes out when the engine increases its
speed after being started.
It lights up again when the engine is stopped.
NOTE:
If the indicator light will not light up with the
main switch “ON”, it shows a lack of the battery
voltage. Recharge the battery. If the engine is
kick started, turn off the light switch.
EC151000
“ENGINE STOP” BUTTON
The “ENGINE STOP” button 1 is located on
the left handlebar. Continue pushing the
“ENGINE STOP” button till the engine comes
to a stop.
START SWITCH
The start switch 1 is located on the right han-
dlebar. Push this switch to crank the engine
with the starter.

GEN
INFO
FONCTIONS DES COMMANDES
STEUERFUNKTIONEN
FUNCIONES DE CONTROL
STEUERFUNKTIONEN
ZÜNDSCHALTER
Die Funktionen der einzelnen
Schalterpositionen sind wie folgt:
ON:
Der Motor kann nur in dieser Position
gestartet werden.
OFF:
Alle elektrischen Schaltkreise sind
deaktiviert.
Zündschalter-Anzeigeleuchte
Der Zündschalter 1 ist mit einer
Anzeigeleuchte 2 ausgestattet, um
versehentliches Vergessen des Aus-
schaltens zu verhindern. Diese
Leuchtet arbeitet wie folgt.
Sie leuchtet auf, wenn der Zünd-
schalter auf “ON” steht.
Sie erlischt, wenn die Motordreh-
zahl nach dem Starten zunimmt.
Es leuchtet erneut auf, wenn der
Motor gestoppt wird.
HINWEIS:
Wenn die Anzeige nicht aufleuchtet,
wenn der Zündschalter auf “ON”
steht, weist dies auf mangelnde Bat-
teriespannung hin. Die Batterie neu
aufladen. Wenn der Motor mit Kick-
starter gestartet wird, den Lichtschal-
ter ausschalten.
MOTORSTOPPSCHALTER “ENGI-
NE STOP”
Der Motorstoppschalter “ENGINE
STOP” 1 befindet sich auf der linken
Seite des Lenkers.
Den Motorstoppschalter “ENGINE
STOP” gedrückt halten, bis der
Motor abstirbt.
STARTSCHALTER
Der Startschalter 1 befindet sich am
rechten Lenkergriff. Diesen Schalter
drücken, um den Motor mit dem
Starter zu kurbeln.
FONCTIONS DES COM-
MANDES
COUPE-CIRCUIT DU MOTEUR
Les fonctions des différentes positions
du coupe-circuit sont les suivantes :
ON:
Le moteur ne peut être mis en marche
que lorsque le coupe-circuit est à cette
position.
OFF:
Tous les circuits électriques sont coupés.
Témoin de coupe-circuit du moteur
Le coupe-circuit du moteur 1 est muni
d’un témoin 2 rappelant qu’il est activé.
Ce témoin fonctionne de la façon sui-
vante.
Il s’allume lorsque le coupe-circuit est
en position “ON” .
Il s’éteint lorsque la vitesse du moteur
augmente après le démarrage.
Il s’allume lorsque le moteur est
arrêté.
N.B.:
Si le témoin ne s’allume pas lorsque le
coupe-circuit du moteur est en position
de “ON”, c’est que la batterie est faible
et doit être rechargée. Si la pédale est uti-
lisée pour mettre le moteur en marche, il
faut éteindre le témoin.
BOUTON D’ARRET DE MOTEUR
“ENGINE STOP”
Ce bouton d’arrêt de moteur “ENGINE
STOP” 1 est situé sur le guidon gauche.
Continuer à appuyer sur le bouton d’arrêt
de moteur “ENGINE STOP” jusqu’a que
ce le moteur s’arrête.
COMMUTATEUR DE DEMAR-
RAGE
Le commutateur de démarrage 1 se
trouve sur la manette droite du guidon.
Appuyer sur ce commutateur pour mettre
le moteur en marche avec le démarreur.
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FUNCIONES DE
CONTROL
INTERRUPTOR PRINCIPAL
Las funciones de las respectivas posicio-
nes del interruptor son como se indica a
continuación:
ON:
El motor solamente puede ser arrancado
en esta posición.
OFF:
Todos los circuitos eléctricos están des-
activados.
Luz indicadora del interruptor princi-
pal
El interruptor principal 1 tiene una luz
indicadora 2 incorporada para evitar
que se olvide de desactivarlo. Esta luz
funciona de la siguiente forma.
Se enciende con el interruptor princi-
pal puesto en “ON”.
Se apaga cuando el motor aumenta su
velocidad después de haberlo arran-
cado.
Se vuelve a encender cuando se para el
motor.
NOTA:
Si la luz indicadora no se enciende con el
interruptor principal en la posición
“ON”, muestra una falta de voltaje en la
batería. Cargue la batería. Si arranca el
motor con el arrancador de pedal, desac-
tive el interruptor de las luces.
BOTÓN DE PARADA DEL MOTOR
“ENGINE STOP”
El botón de parada del motor “ENGINE
STOP” 1 está situado en el manillar
izquierdo. Pulse de forma continuada
este botón hasta que se detenga el motor.
INTERRUPTOR DE ARRANQUE
El interruptor de arranque 1 está en la
parte derecha del manillar. Presione este
interruptor para arrancar el motor con el
arrancador eléctrico.

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GEN
INFO
CONTROL FUNCTIONS
EC152000
CLUTCH LEVER
The clutch lever 1 is located on the left han-
dlebar; it disengages or engages the clutch.
Pull the clutch lever to the handlebar to disen-
gage the clutch, and release the lever to
engage the clutch. The lever should be pulled
rapidly and released slowly for smooth starts.
EC153000
SHIFT PEDAL
The gear ratios of the constant-mesh 5 speed
transmission are ideally spaced. The gears
can be shifted by using the shift pedal 1 on
the left side of the engine.
EC154000
KICKSTARTER
Rotate the kickstarter 1 away from the
engine. Push the starter down lightly with your
foot until the gears engage, then kick smoothly
and forcefully to start the engine. This model
has a primary kickstarter so the engine can be
started in any gear if the clutch is disengaged.
In normal practices, however, shift to neutral
before starting.
1
EC155001
THROTTLE GRIP
The throttle grip 1 is located on the right han-
dlebar; it accelerates or decelerates the
engine. For acceleration, turn the grip toward
you; for deceleration, turn it away from you.
EC156000
FRONT BRAKE LEVER
The front brake lever 1 is located on the right
handlebar. Pull it toward the handlebar to acti-
vate the front brake.

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GEN
INFO
CONTROL FUNCTIONS
EC157000
REAR BRAKE PEDAL
The rear brake pedal 1 is located on the right
side of the machine. Press down on the brake
pedal to activate the rear brake.
FUEL COCK
The fuel cock supplies fuel from the tank to
carburetor and also filters the fuel. The fuel
cock has three positions:
OFF:With the lever in this position fuel will not
flow. Always return the lever to this posi-
tion when the engine is not running.
ON: With the lever in this position fuel flows to
the carburetor. Normal riding is done with
the lever in this position.
RES:With the lever in this position fuel flows to
the carburetor from the reserve section of
the fuel tank after the main supply of the
fuel has been depleted. Normal riding is
possible with the lever is in this position,
but it is recommended to add fuel as
soon as possible.
COLD STARTER KNOB
When cold, the engine requires a richer air-fuel
mixture for starting. A separate starter circuit,
which is controlled by the cold starter knob 1,
supplies this mixture. Pull the cold starter knob
out to open the circuit for starting. When the
engine has warmed up, push it in to close the
circuit.
HOT STARTER LEVER
The hot starter lever 1 is used when starting a
warm engine.
Use the hot starter lever when starting the
engine again immediately after it was stopped
(the engine is still warm). Pulling the hot starter
lever injects secondary air to thin the air-fuel
mixture temporarily, allowing the engine to be
started more easily.

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GEN
INFO
FUEL
Always use the recommended fuel as stated
below. Also, be sure to use new gasoline the
day of a race.
CAUTION:
Use only unleaded gasoline. The use of
leaded gasoline will cause severe damage
to the engine internal parts such as valves,
piston rings, and exhaust system, etc.
NOTE:
If knocking or pinging occurs, use a different
brand of gasoline or higher octane grade.
WARNING
For refueling, be sure to stop the engine
and use enough care not to spill any fuel.
Also be sure to avoid refueling close to a
fire.
Refuel after the engine, exhaust pipe, etc.
have cooled off.
Recommended fuel:
Except for ZA:
Premium unleaded gasoline
only with a research octane
number of 95 or higher.
For ZA:
Premium gasoline
FUEL

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GEN
INFO
STARTING AND BREAK-IN
STARTING AND BREAK-IN
WARNING
Never start or run the engine in a closed
area. The exhaust fumes are poisonous;
they can cause loss of consciousness and
death in a very short time. Always operate
the machine in a well-ventilated area.
CAUTION:
The carburetor on this machine has a
built-in accelerator pump. Therefore,
when starting the engine, do not operate
the throttle or the spark plug will foul.
Unlike a two-stroke engine, this engine
cannot be kick started when the throttle is
open because the kickstarter may kick
back. Also, if the throttle is open the air/
fuel mixture may be too lean for the
engine to start.
Before starting the machine, perform the
checks in the pre-operation check list.
AIR FILTER MAINTENANCE
According to “AIR FILTER CLEANING” section
in the CHAPTER 3, apply the foam-air-filter oil
or its equivalent to the element. (Excess oil in
the element may adversely affect engine start-
ing.)
STARTING A COLD ENGINE
NOTE:
This model is equipped with an ignition circuit
cut-off system. The engine can be started
under the following conditions.
When the transmission is in neutral.
When the clutch is disengaged with the
transmission in any position. However, it is
recommended to shift into neutral before
starting the engine.
1. Inspect the coolant level.
2. Turn the fuel cock to “ON”.
3. Push the main switch to “ON”.
4. Shift the transmission into neutral.
5. Fully open the cold starter knob 1.
6. Start the engine by pushing the start
switch or by kicking the kickstarter.

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GEN
INFO
STARTING AND BREAK-IN
NOTE:
If the engine fails to start by pushing the start
switch, release the switch, wait a few seconds,
and then try again. Each starting attempt
should be as short as possible to preserve the
battery. Do not crank the engine more than
10 seconds on any one attempt. If the engine
does not start with the starter motor, try using
the kickstarter.
WARNING
If the starter motor will not turn when
pushing the start switch, stop pushing it
immediately and kick start the engine in
order to avoid the load on the motor.
Do not open the throttle while kicking the
kickstarter. Otherwise, the kickstarter
may kick back.
7. Return the cold starter knob to its original
position and run the engine at 3,000 ~
5,000 r/min for 1 or 2 minutes.
NOTE:
Since this model is equipped with an accelera-
tor pump, if the engine is raced (the throttle
opened and closed), the air/fuel mixture will be
too rich and the engine may stall. Also unlike a
two-stroke engine, this model can idle.
CAUTION:
Do not warm up the engine for extended
periods of time.

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GEN
INFO
STARTING AND BREAK-IN
STARTING A WARM ENGINE
Do not operate the cold starter knob and throt-
tle. Pull the hot starter lever 1 and start the
engine by pushing the start switch or by kick-
ing the kickstarter forcefully with a firm stroke.
As soon as the engine starts, release the hot
starter lever to close the air passage.
Restarting an engine after a fall
Pull the hot starter lever and start the engine.
As soon as the engine starts, release the hot
starter lever to close the air passage.
The engine fails to start
Pull the hot starter lever all the way out and
while holding the lever, kick the kickstarter 10
to 20 times to clear the engine.
Then, restart the engine.
Refer to “Restarting an engine after a fall”.
* Operate the throttle grip before kick starting.
CAUTION:
Observe the following break-in procedures
during initial operation to ensure optimum
performance and avoid engine damage.
Throttle
grip oper-
ation*Cold
starter
knobHot
starter
lever
Starting a cold engine
Air temperature = less than
5 ˚C (41 ˚F)Open 3
or 4 timesON OFF
Air temperature = more
than 5 ˚C (41 ˚F)None ON OFF
Air temperature (normal tem-
perature) = between 5 ˚C
(41 ˚F) and 25 ˚C (77 ˚F)None ON/OFF OFF
Air temperature = more
than 25 ˚C (77 ˚F)None OFF OFF
Starting an engine after a long
period of timeNone ON OFF
Restarting a warm engine None OFF ON
Restarting an engine after a fall None OFF ON

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GEN
INFO
BREAK-IN PROCEDURES
1. Before starting the engine, fill the fuel
tank with the fuel.
2. Perform the pre-operation checks on the
machine.
3. Start and warm up the engine. Check the
idle speed, and check the operation of
the controls and the “ENGINE STOP”
button. Then, restart the engine and
check its operation within no more than 5
minutes after it is restarted.
4. Operate the machine in the lower gears
at moderate throttle openings for five to
eight minutes.
5. Check how the engine runs when the
machine is ridden with the throttle 1/4 to
1/2 open (low to medium speed) for
about one hour.
6. Restart the engine and check the opera-
tion of the machine throughout its entire
operating range. Restart the machine
and operate it for about 10 to 15 more
minutes. The machine will now be ready
to race.
CAUTION:
After the break-in or before each race,
you must check the entire machine for
loose fittings and fasteners as per
“TORQUE-CHECK POINTS”.
Tighten all such fasteners as required.
When any of the following parts have
been replaced, they must be broken in.
CYLINDER AND CRANKSHAFT:
About one hour of break-in operation is
necessary.
PISTON, RING, VALVES, CAMSHAFTS
AND GEARS:
These parts require about 30 minutes of
break-in operation at half-throttle or less.
Observe the condition of the engine care-
fully during operation.
STARTING AND BREAK-IN