2003 YAMAHA WR 450F engine

1 - 14
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

1 - 15
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.

1 - 16
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.

1 - 17
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

1 - 18
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

GEN
INFO
EINFAHRVORSCHRIFTEN
1. Vor dem Anlassen des Motors
volltanken.
2. Die “ROUTINEKONTROLLE
VOR FAHRTBEGINN” ausfüh-
ren.
3. Den Motor anlassen und
warmlaufen lassen. Dabei die
Leerlaufdrehzahl überwachen
und die Funktion der Bedie-
nungselemente sowie des Mo-
torstoppschalters “ENGINE
STOP” prüfen. Innerhalb der
nächsten fünf Minuten den
Motor wieder anlassen und die
folgenden Schritte ausführen.
4. Die Maschine fünf bis acht Mi-
nuten lang bei mäßiger Gas-
drehgrifföffnung in den unte-
ren Gängen fahren.
5. Den Motorbetrieb etwa eine
Stunde lang bei 1/4 bis 1/2 ge-
öffnetem Gasdrehgriff (niedri-
ge bis mittlere Geschwindig-
keit) überprüfen.
6. Den Motor erneut anlassen
und den Motorbetrieb im ge-
samten Betriebsbereich über-
prüfen. Den Motor abschalten
und noch einmal anlassen und
die Maschine 10 bis 15 Minu-
ten betreiben. Danach ist die
Maschine für Rennen einsatz-
bereit.
ACHTUNG:
Nach dem Einfahren und vor
jedem Rennen die Schraubver-
bindungen gemäß der Tabelle
“ANZUGSMOMENTE KONTROL-
LIEREN” auf festen Sitz prüfen
und vorschriftsmäßig anziehen.
Nach der Erneuerung eines der
folgenden Teile muß die
Maschine erneut eingefahren
werden.
- ZYLINDER UND KURBEL-
WELLE
Etwa eine Stunde Einfahrzeit
- KOLBEN, KOLBENRINGE, VEN-
TILE, NOKKENWELLEN UND -
RÄDER:
Etwa 30 Minuten Einfahrzeit bei
oder unter Halbgas (Sorgfältig
den Motorbetriebüberprüfen.)
MISE EN MARCHE ET RODAGE
ANLASSEN UND EINFAHREN
ARRANQUE Y RODAJE
PROCEDURE DE RODAGE
1. Avant de mettre le moteur en
marche, faire le plein d’essence.
2. Effectuer les contrôles avant utili-
sation de la machine.
3. Lancer le moteur et le laisser se
réchauffer. Vérifier le régime de
ralenti, le fonctionnement des
commandes et l’efficacité du bou-
ton d’arrêt du moteur “ENGINE
STOP”. Remettre ensuite le
moteur en marche et vérifier son
fonctionnement dans les 5 minutes
maximum.
4. Piloter la machine sur les rapports
inférieurs et à régime modéré
durant les cinq à huit premières
minutes. S’arrêter et vérifier l’état
de la bougie; elle devrait donner
des indices de richesse durant le
rodage.
5. Vérifier le fonctionnement du
moteur en roulant pendant envi-
ron 1 heure à une ouverture des
gaz de 1/4 à 1/2 (petite à moyenne
vitesse.)
6. Remettre le moteur en marche et
vérifier son fonctionnement à
tous les régimes. Arrêter et véri-
fier la bougie. Relancer le moteur
et piloter la machine pendant 10 à
15 minutes supplémentaires. Elle
sera alors prête pour la course.
ATTENTION:
Après le rodage ou avant chaque
course, il faut vérifier toutes les fixa-
tions et serrages comme indiqué
dans “POINTS DE VERIFICA-
TION DE COUPLE DE SER-
RAGE”.
Serrer toutes ces fixations comme
requis.
Après avoir remplacé les pièces sui-
vantes, un nouveau rodage est
nécessaire.
CYLINDRE ET VILEBREQUIN:
Une heure environ de rodage est
nécessaire.
PISTONS, SEGMENTS, SOUPAPES,
ARBRES A CAMES:
Ces pièces nécessitent un rodage de
30 minutes environ à une ouverture
des gaz de maximum 1/2. Surveiller
attentivement l’état du moteur pen-
dant la marche.PROCEDIMIENTOS DE RODAJE
1. Antes de arrancar el motor, llene
el depósito de combustible.
2. Realice las comprobaciones en el
vehículo previas a la conducción.
3. Arranque y deje que se caliente el
motor. Compruebe la velocidad
de ralentí, el funcionamiento de
los controles y el botón de parada
del motor “ENGINE STOP”. A
continuación, arranque nueva-
mente el motor y compruebe su
funcionamiento durante 5 minu-
tos como máximo después de
haberlo arrancado.
4. Maneje el vehículo en las mar-
chas inferiores y modere las aber-
turas del acelerador durante cinco
u ocho minutos.
5. Compruebe cómo funciona el
motor cuando maneje la motoci-
cleta con el acelerador 1/4 a 1/2
abierto (velocidad baja a mode-
rada) durante una hora aproxima-
damente.
6. Arranque el motor otra vez y
compruebe el funcionamiento del
vehículo en toda su gama de fun-
cionamiento. Arranque el motor y
maneje el vehículo durante otros
10 a 15 minutos. El vehículo ya
está preparado para la carrera.
ATENCION:
Después del rodaje o antes de cada
carrera, debe comprobar en todo el
vehículo la existencia de acopla-
mientos y remaches flojos así como
“TORSIONES-PUNTOS DE COM-
PROBACIÓN”.
En caso necesario, apriete todos los
remaches.
Cuando haya sustituido cualquiera
de las siguientes piezas, éstas deben
ser sometidas al rodaje.
CILINDRO Y CIGÜEÑAL:
Es necesario realizar aproximada-
mente una hora de conducción de
rodaje.
PISTÓN, ANILLO, VÁLVULAS,
ÁRBOLES DE LEVAS Y ENGRA-
NAJES:
Estas piezas requieren alrededor de
30 minutos de funcionamiento de
rodaje con el acelerador a la mitad o
inferior. Observe el estado del
motor cuidadosamente durante el
funcionamiento del mismo.
1 - 18

GEN
INFO
1 - 19
TORQUE-CHECK POINTS
TORQUE-CHECK POINTS
NOTE:
Concerning the tightening torque, refer to
“MAINTENANCE SPECIFICATIONS” section
in the CHAPTER 2.
Frame to rear frame
Fuel tank to frame
Silencer to rear frame
Frame to engine
Engine bracket to engine
Engine bracket to frame
Steering shaft to frame
Steering shaft to handle crown
Handle crown to handlebar
Front fork to handle crown
Front fork to under bracket
Assembly of links
Link to frame
Link to shock absorber
Link to swingarm
Shock absorber to frame
Tightening of pivot shaft
Tightening of front axle
Tightening of axle holder
Tightening of rear axle
Wheel to sprocket
Caliper to front fork
Brake disc to wheel
Tightening of union bolt
Master cylinder to handlebar
Tightening of air bleeder
Brake pedal to frame
Brake disc to wheel
Tightening of union bolt
Master cylinder to frame
Tightening of air bleeder
Fuel tank to fuel cock
Tightening of oil hose clamp Frame construction
Combined seat and tank
Exhaust system
Engine mounting
Steering Steering shaft to
handlebar
Suspension Front Steering shaft to front
fork
Rear For link type
Rear Installation of shock
absorber
Rear Installation of swing-
arm
Wheel Installation of wheel Front
Rear
Brake Front
Rear
Fuel system
Lubrication system

1 - 20
GEN
INFO
CLEANING AND STORAGE
EC1B0000
CLEANING AND STORAGE
EC1B1000
CLEANING
Frequent cleaning of your machine will
enhance its appearance, maintain good over-
all performance, and extend the life of many
components.
1. Before washing the machine, block off
the end of the exhaust pipe to prevent
water from entering. A plastic bag
secured with a rubber band may be used
for this purpose.
2. If the engine is excessively greasy, apply
some degreaser to it with a paint brush.
Do not apply degreaser to the chain,
sprockets, or wheel axles.
3. Rinse the dirt and degreaser off with a
garden hose; use only enough pressure
to do the job.
CAUTION:
Excessive hose pressure may cause water
seepage and contamination of wheel bear-
ings, front forks, brakes and transmission
seals. Many expensive repair bills have
resulted from improper high pressure
detergent applications such as those avail-
able in coin-operated car washers.
4. After the majority of the dirt has been
hosed off, wash all surfaces with warm
water and a mild detergent. Use an old
toothbrush to clean hard-to-reach places.
5. Rinse the machine off immediately with
clean water, and dry all surfaces with a
soft towel or cloth.
6. Immediately after washing, remove
excess water from the chain with a paper
towel and lubricate the chain to prevent
rust.
7. Clean the seat with a vinyl upholstery
cleaner to keep the cover pliable and
glossy.