tow YAMAHA YZ250F 2002 Owners Manual

1 - 11
GEN
INFO
CONTROL FUNCTIONS
DECOMPRESSION LEVER
CAUTION:
Never use the decompression lever after
the engine is started. The engine may be
damaged if you use the decompression
lever while it is running.
The decompression lever 1 is located on the
left handlebar and is used when starting the
engine. Squeezing the decompression lever
presses down on the exhaust valve and
releases the pressure in the cylinder head.
This enables the vehicle to be kickstarted
more easily.
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.
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.

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.
8. Automotive wax may be applied to all
painted or chromed surfaces. Avoid com-
bination cleaner-waxes, as they may con-
tain abrasives.
9. After completing the above, start the
engine and allow it to idle for several min-
utes.

GEN
INFO
NETTOYAGE ET RANGEMENT
REINIGUNG UND STILLEGUNG
PULIZIA ED IMMAGAZZINAGGIO
REINIGUNG UND STILLE-
GUNG
REINIGUNG
Eine regelmäßige, gründliche
Wäsche sorgt nicht nur für gutes
Aussehen, sondern verbessert auch
das allgemeine Betriebsverhalten,
reduziert Verschleiß und bewirkt
somit eine längere Lebensdauer und
besseren Werterhalt.
1. Vor der Wäsche eine Plastik-
tüte über die Schalldämpfer-
öffnung stülpen und mit einem
Gummiband sichern, damit
kein Wasser eindringen kann.
2. Bei stark veröltem Motor mit ei-
nem Pinsel Kaltreiniger auftra-
gen. Jedoch keinen Kaltreiniger
auf Antriebskette, Kettenräder
und Radachsen bringen.
3. Schmutz und Kaltreiniger mit ei-
nem Wasserschlauch gründlich
abspülen. Dabei den Wasser-
druck möglichst gering halten.
ACHTUNG:
Durch zu hohen Wasserdruck
können Wasser und Verunreini-
gungen in Radlager, Teleskopga-
bel, Schwingenlager, Bremsen,
Getriebedichtungen und elektri-
sche Komponenten eindringen.
Viele teure Reparaturen sind die
Folge falscher Anwendung von
Hochdruckreinigern (Dampfstrah-
ler), wie sie z. B. bei Münzwasch-
anlagen zu finden sind.
4. Nach dem Abspülen des gro-
ben Schmutzes alle Oberflä-
chen mit warmem Wasser und
einem milden Reinigungsmit-
tel abwaschen. Schwer zu-
gängliche Stellen lassen sich
am besten mit einer alten
Zahnbürste oder einer Fla-
schenbürste reinigen.
5. Unmittelbar danach das Fahr-
zeug mit sauberem Wasser
abspülen und mit einem
Waschleder, sauberen Tuch
oder weichen, saugfähigen
Lappen abtrocknen.
6. Die Kette trocknen und sofort
schmieren, um Korrosion zu
verhindern.
7. Die Sitzbank mit einem Reini-
ger für Vinylpolster abwischen,
damit der Bezug geschmeidig
und glänzend bleibt.
8. Lack- und Chromflächen kön-
nen mit Autowachs poliert
werden. Kombinierte Reiniger
und Polituren sind zu vermei-
den, da sie oft Scheuermittel
enthalten, die den Lack auf
Tank und Verkleidungsteilen
beschädigen würden.
9. Nach der Wäsche den Motor an-
lassen und warmlaufen lassen.
NETTOYAGE ET RANGE-
MENT
NETTOYAGE
Un nettoyage fréquent de la machine
améliorera son aspect, maintiendra ses
bonnes performances et augmentera la
durée de service de bon nombre de ses
composants.
1. Avant de laver la moto, boucher
la sortie du pot d’échappement
pour éviter toute pénétration
d’eau. Un sachet en plastique
retenu par un élastique fera
l’affaire.
2. Si le moteur est fortement
encrassé, appliquer un peu de
dégraissant au pinceau. Eviter
tout contact avec la chaîne, ses
pignons et les axes de roue.
3. Rincer la boue et le dégraissant
au tuyau d’arrosage, en utilisant
juste la pression suffisante.
ATTENTION:
Une pression excessive risque de pro-
voquer des infiltrations d’eau dans les
roulements des roues, la fourche
avant, des freins et les joints de la
transmission. Noter que bien des notes
de réparation onéreuses ont résulté de
l’emploi abusif des vaporisateurs de
détergent à haute pression, tels que
ceux qui équipent les laveries automa-
tiques de voitures.
4. Après avoir chassé la majeure
partie de la boue, laver toutes les
surfaces avec de l’eau chaude et
un détergent neutre. Utiliser une
vieille brosse à dents pour attein-
dre les endroits difficiles d’accès.
5. Rincer immédiatement l’engin
avec de l’eau propre et sécher
toutes les surfaces avec un chif-
fon doux.
6. Immédiatement après le lavage,
éliminer l’excès d’eau de la
chaîne avec des mouchoirs en
papier et lubrifier la chaîne pour
éviter qu’elle ne rouille.
7. Nettoyer la selle avec un produit
pour meubles rembourrés pour
que sa housse reste souple et
brillante.
8. Un encaustique pour automobile
peut être appliqué sur toutes les
surfaces peintes et chromées. Evi-
ter les liquides de nettoyage à
encaustique, car ils contiennent
de l’abrasif.
9. Les opérations ci-dessus termi-
nées, lancer le moteur et le laisser
tourner pendant quelques minu-
tes.
PULIZIA ED IMMAGAZ-
ZINAGGIO
PULIZIA
Una pulizia frequente del veicolo ne
migliora l’aspetto, aiuta a mantenere
buone prestazioni generali ed aumenta la
durata utile di molti componenti.
1. Prima di lavare il veicolo, bloc-
care l’estremità del tubo di sca-
rico per impedire la penetrazione
dell’acqua. A tal fine è possibile
utilizzare una busta di plastica
fermata con un elastico.
2. Se il motore è eccessivamente
grasso, applicare un agente sgras-
sante con un pennello. Non appli-
care l’agente sgrassante alla
catena, alle corone o agli assi
della ruota.
3. Sciaquare via lo sporco e l’agente
sgrassante con una pompa da
giardino, avendo cura di impie-
gare solo la pressione necessaria
allo scopo.
ATTENZIONE:
Una pressione eccessiva potrebbe cau-
sare infiltrazioni d’acqua e contamina-
zione dei cuscinetti delle ruote, delle
forcelle anteriori, dei freni e delle tenute
della trasmissione. Moltissime costose
riparazioni sono state il risultato di
applicazioni improprie di detergente ad
alta pressione quali quelli disponibili
presso i lavaggi auto a gettone.
4. Dopo aver lavato via la maggior
parte dello sporco, lavare tutte le
superfici con acqua calda ed un
detergente delicato. Utilizzare un
vecchio spazzolino da denti per
pulire i punti difficili da raggiun-
gere.
5. Sciacquare immediatamente il vei-
colo con acqua pulita ed asciugare
tutte le superfici con un asciuga-
mano o un panno morbido.
6. Immediatamente dopo il lavaggio,
rimuovere dalla catena l’acqua in
eccesso con un panno carta e lubri-
ficare la catena per impedire la for-
mazione di ruggine.
7. Pulire la sella con un detergente per
tappezzeria in vinile per mantenere
il rivestimento morbido e lucido.
8.È possibile applicare cera per
autovetture su tutte le superfici
verniciate o cromate. Evitare la
combinazione di cera e deter-
gente in quanto potrebbe conte-
nere abrasivi.
9. Dopo aver terminato, avviare il
motore e farlo funzionare in folle
per qualche minuto.
1 - 20

3 - 5
INSP
ADJ
EC350000
ENGINE
COOLANT LEVEL INSPECTION
WARNING
Do not remove the radiator cap 1, drain
bolt and hoses when the engine and radia-
tor are hot. Scalding hot fluid and steam
may be blown out under pressure, which
could cause serious injury.
When the engine has cooled, place a thick
towel over the radiator cap, slowly rotate
the cap counterclockwise to the detent.
This procedure allows any residual pres-
sure to escape. When the hissing sound
has stopped, press down on the cap while
turning counterclockwise and remove it.
CAUTION:
Hard water or salt water is harmful to the
engine parts. You may use distilled water, if
you can’t get soft water.
1. Place the machine on a level place, and
hold it in an upright position.
2. Remove:
Radiator cap
3. Check:
Coolant level a
Coolant level low → Add coolant.
1Radiator
1a
ENGINE/COOLANT LEVEL INSPECTION

3 - 25
INSP
ADJ
CHASSIS/BRAKE SYSTEM AIR BLEEDING
EC360000
CHASSIS
EC361012
BRAKE SYSTEM AIR BLEEDING
WARNING
Bleed the brake system if:
The system has been disassembled.
A brake hose has been loosened or
removed.
The brake fluid is very low.
The brake operation is faulty.
A dangerous loss of braking performance
may occur if the brake system is not prop-
erly bleed.
1. Remove:
Reservoir cap
Diaphragm
Protector (rear brake)
2. Bleed:
Brake fluid
ÅFront
ıRear
Air bleeding steps:
a. Add proper brake fluid to the reservoir.
b. Install the diaphragm. Be careful not to
spill any fluid or allow the reservoir to
overflow.
c. Connect the clear plastic tube 2 tightly
to the caliper bleed screw 1.
d. Place the other end of the tube into a
container.
e. Slowly apply the brake lever or pedal
several times.
f. Pull the lever in or push down on the
pedal. Hold the lever or pedal in position.
g. Loosen the bleed screw and allow the
lever or pedal to travel towards its limit.
h. Tighten the bleed screw when the lever
or pedal limit has been reached; then
release the lever or pedal.
T R..
Bleed screw:
6 Nm (0.6 m • kg, 4.3 ft • lb)
i. Repeat steps (e) to (h) until of the air
bubbles have been removed from the
system.
Å
ı

4 - 5
ENG

RADIATOR
EC456000
HANDLING NOTE
WARNING

Do not remove the radiator cap when the
engine and radiator are hot. Scalding hot
fluid and steam may be blown out under
pressure, which could cause serious
injury.
When the engine has cooled, open the radi-
ator cap by the following procedure:
Place a thick rag, like a towel, over the radi-
ator cap, slowly rotate the cap counter-
clockwise to the detent. This procedure
allows any residual pressure to escape.
When the hissing sound has stopped,
press down on the cap while turning coun-
terclockwise and remove it.
EC454000
INSPECTION
EC444100
Radiator
1. Inspect:

Radiator core
1

Obstruction
→
Blow out with com-
pressed air through rear of the radiator.
Bent fin
→
Repair/replace.
EC455000
ASSEMBLY AND INSTALLATION
Radiator
1. Install:

O-ring
1

Radiator pipe
2


Bolt (radiator pipe)
3

NOTE:

Apply the lithium soap base grease on the O-
ring.
2. Install:

Radiator breather hose
1
Radiator hose 4 (longer) 2
Radiator hose 2 (shorter) 3
To left radiator 4.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 77
ENGKICK SHAFT AND SHIFT SHAFT
3. Install:
Spring guide 1
NOTE:
Slide the spring guide into the kick shaft, make
sure the groove a in the spring guide fits on
the stopper of the torsion spring.
4. Install:
Kick shaft assembly 1
Washer 2
NOTE:
Apply the molybdenum disulfide grease on
the contacting surfaces of the kick shaft stop-
per a and stopper plate 3.
Apply the engine oil on the kick shaft.
Slide the kick shaft assembly into the crank-
case and make sure the kick shaft stopper a
fits into the stopper plate.
5. Hook:
Torsion spring 1
NOTE:
Turn the torsion spring clockwise and hook
into the proper hole a in the crankcase.
Kick idle gear
1. Install:
Kick idle gear 1
Washer 2
Circlip 3
NOTE:
Apply the engine oil on the kick idle gear
inner circumference.
Install the kick idle gear with its depressed
side a toward you.

7 - 11
TUN
EC720000
CHASSIS
Selection of the secondary reduction ratio
(Sprocket)
Secondary
reduction =
ratio
reduction ratio>
It is generally said that the secondary gear
ratio should be reduced for a longer straight
portion of a speed course and should be
increased for a course with many corners.
Actually, however, as the speed depends on
the ground condition of the day of the race,
be sure to run through the circuit to set the
machine suitable for the entire course.
In actuality, it is very difficult to achieve set-
tings suitable for the entire course and some
settings may be sacrificed. Thus, the settings
should be matched to the portion of the
course that has the greatest effect on the
race result. In such a case, run through the
entire course while making notes of lap times
to find the best balance; then, determine the
secondary reduction ratio.
If a course has a long straight portion where
a machine can run at maximum speed, the
machine is generally set such that it can
develop its maximum revolutions toward the
end of the straight line, with care taken to
avoid the engine over-revving.
NOTE:
Riding technique varies from rider to rider and
the performance of a machine also vary from
machine to machine. Therefore, do not imitate
other rider’s settings from the beginning but
choose your own setting according to the level
of your riding technique.Standard secondary
reduction ratio48/13 (3.692)
Number of rear wheel sprocket teeth
Number of drive sprocket teeth
SETTING

7 - 21
TUNSETTING
EC72H002
Suspension setting
Front fork
NOTE:
If any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
Before any change, set the rear shock absorber sunken length to the standard figure 90 ~
100 mm (3.5 ~ 3.9 in).
SymptomSection
Check Adjust
JumpLarge
gapMedium
gapSmall
gap
Stiff over entire range

Compression damping
Oil level (oil amount)
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with soft spring.
Unsmooth movement
over entire range

Outer tube
Inner tube
Under bracket tightening
torqueCheck for any bends, dents, and other noticeable
scars, etc. If any, replace affected parts.
Retighten to specified torque.
Poor initial
movement

Rebound damping
Oil sealTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Apply grease in oil seal wall.
Soft over entire range,
bottoming out

Compression damping
Oil level (oil amount)
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Increase oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with stiff spring.
Stiff toward stroke end
Oil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
Soft toward stroke end,
bottoming out
Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Stiff initial movement
Compression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front posture

Compression damping
Rebound damping
Balance with rear end
Oil level (oil amount)Turn adjuster clockwise (about 2 clicks) to increase
damping.
Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 95 ~ 100 mm (3.7 ~ 3.9 in) when
one passenger is astride seat (lower rear posture).
Increase oil level by about 5 mm (0.2 in).
“Obtrusive” front, tend-
ing to upper front pos-
ture

Compression damping
Balance with rear end
Spring
Oil lever (oil amount)Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 90 ~ 95 mm (3.5 ~ 3.7 in) when
one passenger is astride seat (upper rear posture).
Replace with soft spring.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).