tow YAMAHA WR 426F 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
FEC1B0000
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,
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
LIMPIEZA Y ALMACENAMIENTO
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 kön-
nen Wasser und Verunreinigun-
gen in Radlager, Teleskopgabel,
Schwingenlager, Bremsen, Getrie-
bedichtungen und elektrische
Komponenten eindringen. Viele
teure Reparaturen sind die Folge
falscher Anwendung von Hoch-
druckreinigern (Dampfstrahler),
wie sie z. B. bei Münzwaschanla-
gen 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
avec un tuyau d’arrosage, en utili-
sant 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.
LIMPIEZA Y ALMACE-
NAMIENTO
LIMPIEZA
La frecuente limpieza de su vehículo
intensificará su aspecto, manteniendo un
rendimiento general óptimo y exten-
diendo la duración de muchos de sus
componentes.
1. Antes de lavar el vehículo, tape el
extremo del tubo de escape para
evitar que penetre agua. Puede
utilizar una bolsa de plástico
sujeta por una goma.
2. Si el motor está engrasado en
exceso, aplique con un pincel un
desengrasante. No aplique el des-
engrasante a la cadena, a los piño-
nes o a los ejes de la rueda.
3. Aclare la suciedad y el desengra-
sante con una manguera; utilice
únicamente la presión necesaria
para realizar este trabajo.
PRECAUCION:
Una presión excesiva puede provocar
filtraciones y contaminación en los
cojinetes de la rueda, las horquillas
delanteras, los frenos y los retenes de
la caja de cambios. Una aplicación de
detergente a una presión alta inade-
cuada puede originar reparaciones
costosas como las que se producen en
los túneles de lavado automático.
4. Después de haber limpiado la
mayor parte de la suciedad, lim-
pie todas las superficies con agua
templada y detergente suave. Uti-
lice un cepillo de dientes viejo
para limpiar las zonas poco acce-
sibles.
5. Aclare inmediatamente el vehí-
culo con agua limpia y seque
todas las superficies con una toa-
lla o un paño suave.
6. Inmediatamente después de lavar
el vehículo, extraiga el exceso de
agua de la cadena con un papel de
cocina y engrase la cadena para
evitar que se oxide.
7. Limpie el asiento con un limpia-
dor de tapicería vinílico para
mantenerlo flexible y brillante.
8. Puede aplicar cera de automotor a
todas las superficies pintadas o
cromadas. Evite la combinación
de limpiadores y ceras ya que
contienen sustancias abrasivas.
9. Después de completar el procedi-
miento, arranque el motor y
déjelo unos minutos en ralentí.
1 - 20

2 - 39
SPECCABLE ROUTING DIAGRAM
ÈMake sure that the TPS read
coupler does not go outside
the chassis.
ÔFasten the TPS lead under the
coupler to the frame with a
plastic locking tie.
Pass the carburetor breather
hoses and overflow hose
between the connecting rod
and cross tube (frame).
ÒFasten the neutral switch lead
and oil hose together with a
plastic locking tie and cut off
the tie end.
˜Fasten the cylinder head
breather hose with the hose
holder.
ˆFasten the neutral switch lead
to the frame with a plastic
band ends toward the rear of
the frame.ØFasten the neutral switch lead
and CDI magneto lead
together with a plastic band.
∏Pass the clutch cable through
the cable guide.
ŒPass the cylinder head
breather hose along the inner
side of the radiator pipe.
ÂPass the clutch cable between
the frame and radiator and
over the lower boss on the
radiator.
ÍPass the neutral switch lead
and CDI magneto lead through
the cable guide and over the
middle radiator mounting boss.
Then, pass the decompression
cable under the middle radia-
tor mounting boss and along
the left side of the neutral
switch lead and CDI magneto
lead.ÊPass the clutch cable through
the cable guide.
ËFit the brake hose into the
guides on the protector.
◊Fasten the ignition coil lead
(in the sub wire harness) on
the upper inside of the frame
and cut off the tie end.
„Pass the ignition coil lead (in
the sub wire harness) under
the cushion bracket (frame).
≈Fasten the ignition coil lead
(in the sub wire harness) to
the frame with a plastic lock-
ing tie and cut off the tie end.
ÁPass the carburetor breather
hoses, overflow hose and
coolant reservoir tank
breather hose so that all there
hoses do not contact the rear
shock absorber.

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. Inspect:
Coolant level
Coolant level should be between the
maximum a and minimum b marks.
Coolant level is below the “LOW” level
line → Add soft water (tap water) up to
the proper level.
3. Start the engine and let it warm up for
several minutes.
4. Turn off the engine and check the coolant
level again.
NOTE:
Before checking the coolant level, wait a few
minutes until the coolant settles.
LOWFULLCOOLANT
a
b
COOLANT REPLACEMENT
WARNING
Do not remove the radiator cap when the
engine is hot.
ENGINE/COOLANT LEVEL INSPECTION/
COOLANT REPLACEMENT

3 - 26
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:
Master cylinder 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 - 6
ENGRADIATOR
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:
Pipe 1 1
Hose 1 2
Pipe 2 3
Hose 3 4
Hose 4 5
2. Install:
Hose 2 1
Radiator (left) 2
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 83
ENGKICK AXLE AND SHIFT SHAFT
3. Install:
Spring guide 1
NOTE:
Slide the spring guide into the kick axle, make
sure the groove a in the spring guide fits on
the stopper of the torsion spring.
4. Install:
Kick axle assembly 1
Plain washer 2
NOTE:
Apply the molybdenum disulfide grease on
the contacting surfaces of the kick axle stop-
per a and stopper plate 3.
Apply the engine oil on the kick axle.
Slide the kick axle assembly into the crank-
case and make sure the kick axle stopper 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
Plain washer 2
Circlip 3
NOTE:
Install the kick idle gear with its depressed
side a toward you.
Apply the engine oil on the kick idle gear
inner circumference.
New

TUN
REGLAGE
EINSTELLUNG
AJUSTE
Einstellung der Leerlaufgemisch-
Regulierschraube
Der Kraftstoffgehalt des Luft-Kraft-
stoff-Gemisches bei 0–1/4 Gas kann
durch Drehen der Leerlaufgemisch-
Regulierschraube 1 eingestellt wer-
den. Die Leerlaufgemisch-Regulier-
schraube heraus- bzw. hineindrehen,
um bei niedrigen Drehzahlen ein fet-
teres bzw. mageres Gemisch zu
erhalten.
* Nicht USA
HINWEIS:
Wenn die Leerlaufdrehzahl
schwanken sollte, die Leerlaufge-
misch-Regulierschraube nur bis
maximal 1/2 Drehung in beide
Richtungen drehen.
Um den Kraftstoff-Fluß bei kleinem
Öffnungswinkel der Drosselklappe
zu optimieren, wurde die Leerlauf-
gemisch-Regulierschraube im
Werk für jeden Motor einzeln opti-
mal eingestellt. Ehe die Leerlauf-
gemisch-Regulierschraube neu
eingestellt wird, die Schraube ganz
hineindrehen und die Anzahl der
Umdrehungen zählen. Diese An-
zahl als werkseitige Voreinstel-
lung für das Herausdrehen der
Schraube aufzeichnen.
Wirkung der Einstellung der leer-
laufgemisch-Regulierschraube
ÅLeerlauf
ıVollgas
12 1/8 Drehungen heraus
21 1/8 Drehung heraus
31 5/8 Drehungen heraus
Standard-Posi-
tion der Leer-
laufgemisch-
Regulier-
schraubeWR426F: 1 5/8
*1-1/8
WR400F: 1 1/2
(Beispiel)
1/4 1/2 3/4
+5%
–5% AB
1
23
Réglage de la vis de ralenti
La richesse de l’émulsion air-essence à
une ouverture des gaz de 0 à 1/4 se règle
en tournant la vis de ralenti 1. Serrer la
vis de ralenti afin d’appauvrir et la des-
serrer afin d’enrichir l’émulsion à vites-
ses réduites.
* Excepté pour USA
N.B.:
Si le régime de ralenti n’est pas stable,
tourner la vis de ralenti d’un seul 1/2
tour dans un sens ou l’autre.
La vis de ralenti de chaque véhicule
est réglée individuellement en usine
afin de maximiser le flux de carburant
à petite ouverture des gaz. Avant de
régler la vis de ralenti, la visser tout à
fait et compter le nombre de tours
nécessaires. Noter ce chiffre, car il
s’agit du réglage d’usine.
Effets du réglage de la vis de ralenti
(référence)
ÅRalenti
ıComplètement ouvert
1Desserrer de 2-1/8 tours
2Desserrer de 1-1/8 tour
3Desserrer de 1-5/8 de tours
Position standard
de la vis de ralentiWR426F: 1-5/8
*1-1/8
WR400F: 1-1/2
(exemple)
1/4 1/2 3/4
+5%
–5% AB
1
23
7 - 5
Ajuste del tornillo piloto
Se puede ajustar la riqueza de la mezcla
de aire y combustible con el acelerador
desde completamente cerrado hasta
abierto en 1/4 girando el tornillo piloto
1. Si gira hacia dentro el tornillo piloto,
la mezcla se empobrecerá a velocidades
bajas y si lo gira hacia fuera, se enrique-
cerá dicha mezcla.
* Excepto para USA
NOTA:
Si fluctúa la velocidad de ralentí, gire
el tornillo piloto sólo 1/2 de vuelta en
cualquier dirección.
Para optimizar el flujo del combusti-
ble a una abertura menor del acelera-
dor, cada tornillo piloto de la máquina
ha sido ajustado individualmente en
fábrica. Antes de ajustar el tornillo
piloto, gírelo completamente hacia
dentro y cuente el número de vueltas.
Registre este número como el número
de vueltas hacia fuera del ajuste de
fábrica.
Efectos del ajuste del tornillo piloto
(referencia)
ÅRalentí
ıCompletamente abierto
12-1/8 de vueltas hacia fuera
21-1/8 de vueltas hacia fuera
31-5/8 de vueltas hacia fuera
Posición estándar
del tornillo pilotoWR426F: 1-5/8
*1-1/8
WR400F: 1-1/2
(ejemplo)
1/4 1/2 3/4
+5%
–5% AB
1
23

7 - 11
TUN
EC720000
CHASSIS
EC71P002
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 ratio50/14 (3.571)
SETTING
Number of driven sprocket teeth
Number of drive sprocket teeth