2007 YAMAHA YZ450F Engine

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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 kick starter 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.
STARTING A COLD ENGINE
1. Inspect the coolant level.
2. Turn the fuel cock to “ON”.
3. Shift the transmission into neutral.
4. Fully open the cold starter knob 1.
5. Kick the kick starter.
WARNING
Do not open the throttle while kicking the
kick starter. Otherwise, the kick starter may
kick back.
1

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GEN
INFO
STARTING AND BREAK-IN
6. 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 kicking the kick starter 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 kick starter 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 operation
of the machine throughout its entire operat-
ing range. Restart the machine and oper-
ate 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 Starten voll tanken.
2. Die “Routinekontrolle vor Fahrtbeginn” aus-
führen.
3. Den Motor anlassen und einige Minuten
lang betreiben. Die Leerlaufdrehzahl und
die Funktion der Bedienelemente ein-
schließlich des Motorstoppschalters
“ENGINE STOP” kontrollieren. Den Motor
erneut anlassen und innerhalb 5 Minuten
dessen Funktion kontrollieren.
4. Die Maschine 5–8 Minuten lang mit mäßi-
gem Gas im unteren Gangbereich betrei-
ben.
5. Den Motorbetrieb bei 1/4 bis 1/2 geöffne-
tem Gasdrehgriff (niedriger bis mäßiger
Geschwindigkeit) etwa eine Stunde lang
überwachen.
6. Den Motor erneut starten und den gesam-
ten Betriebsbereich kontrollieren. Den
Motor erneut starten und weiter 10–15
Minuten lang betreiben. Die Maschine ist
nun rennfertig.
ACHTUNG:
Entsprechend dem Abschnitt “ANZUGS-
DREHMOMENTE KONTROLLIEREN”,
nach dem Einfahren sowie vor jedem
Rennen sämtliche Befestigungselemente
kontrollieren.
Befestigungselemente ggf. vorschrifts-
mäßig festziehen.
Folgende Bauteile müssen nach dem
Auswechseln eingefahren werden.
ZYLINDER UND KURBELWELLE:
Eine einstündige Einfahrzeit einlegen.
KOLBEN, KOLBENRINGE, VENTILE,
NOCKLENWELLEN UND RITZEL:
Eine halbstündige Einfahrzeit mit maxi-
mal halb geöffnetem Gasdrehgriff einle-
gen. Den Motorbetrieb gründlich
überwachen.
MISE EN MARCHE ET RODAGE
STARTEN UND EINFAHREN
PROCEDURE DE RODAGE
1. Avant de démarrer le moteur, faire le plein du
réservoir de carburant.
2. Effectuer les contrôles avant utilisation.
3. Mettre le moteur en marche et le laisser chauf-
fer. Contrôler le régime de ralenti et le bon
fonctionnement des commandes et du bouton
“ENGINE STOP”. Redémarrer ensuite le
moteur et contrôler son fonctionnement dans
les 5 minutes maximum qui suivent son redé-
marrage.
4. Rouler pendant cinq à huit minutes sur les rap-
ports inférieurs et à régime modéré.
5. Contrôler le fonctionnement du moteur lorsque
la moto est utilisée pendant une heure environ
aux régimes bas à moyens (ouverture des gaz
1/4 à 1/2).
6. Remettre le moteur en marche et vérifier le
fonctionnement de la moto à toutes les vitesses.
Redémarrer la moto et rouler pendant 10 à 15
minutes environ. La moto est maintenant prête
pour la course.
ATTENTION:
Après le rodage ou avant chaque course, il est
indispensable de contrôler le bon serrage des
raccords et des fixations conformément aux
instructions de la section “POINTS DE VERI-
FICATION DES COUPLES DE SERRAGE”.
Resserrer au couple requis tout élément des-
serré.
Si l’une quelconque des pièces suivantes a été
remplacée, un nouveau rodage est nécessaire.
CYLINDRE ET VILEBREQUIN:
Roder pendant environ une heure.
PISTON, SEGMENT, SOUPAPES, ARBRES
A CAMES ET PIGNONS:
Ces pièces nécessitent un rodage d’environ 30
minutes à une ouverture des gaz de 1/2 au
maximum. Surveiller attentivement l’état du
moteur pendant le rodage.
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GEN
INFO
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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
Tightening of brake hose holder
Brake pedal to frame
Brake disc to wheel
Tightening of union bolt
Master cylinder to frame
Tightening of air bleeder
Tightening of brake hose holder
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
swingarm
Wheel Installation of wheel Front
Rear
Brake Front
Rear
Fuel system
Lubrication system

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GEN
INFO
CLEANING AND STORAGE
EC1B0000
CLEANING AND STORAGE
EC1B1000
CLEANING
Frequent cleaning of your machine will
enhance its appearance, maintain good overall
performance, and extend the life of many com-
ponents.
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, sprock-
ets, or wheel axles.
3. Rinse the dirt and degreaser off with a gar-
den 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.

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GEN
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CLEANING AND STORAGE
8. Automotive wax may be applied to all
painted or chromed surfaces. Avoid combi-
nation cleaner-waxes, as they may contain
abrasives.
9. After completing the above, start the
engine and allow it to idle for several min-
utes.
EC1B2001
STORAGE
If your machine is to be stored for 60 days or
more, some preventive measures must be
taken to avoid deterioration. After cleaning the
machine thoroughly, prepare it for storage as
follows:
1. Drain the fuel tank, fuel lines, and the car-
buretor float bowl.
2. Remove the spark plug, pour a tablespoon
of SAE 10W-30 motor oil in the spark plug
hole, and reinstall the plug. With the engine
stop switch pushed in, kick the engine over
several times to coat the cylinder walls with
oil.
3. Remove the drive chain, clean it thoroughly
with solvent, and lubricate it. Reinstall the
chain or store it in a plastic bag tied to the
frame.
4. Lubricate all control cables.
5. Block the frame up to raise the wheels off
the ground.
6. Tie a plastic bag over the exhaust pipe out-
let to prevent moisture from entering.
7. If the machine is to be stored in a humid or
salt-air environment, coat all exposed
metal surfaces with a film of light oil. Do not
apply oil to rubber parts or the seat cover.
NOTE:
Make any necessary repairs before the
machine is stored.