2003 YAMAHA WR 250F check engine

IMPORTANT NOTICE
THIS MACHINE IS DESIGNED
STRICTLY FOR COMPETITION
USE, ONLY ON A CLOSED
COURSE. It is illegal for this machine
to be operated on any public street,
road, or highway. Off-road use on
public lands may also be illegal.
Please check local regulations
before riding.
1. THIS MACHINE IS TO BE
OPERATED BY AN EXPERI-
ENCED RIDER ONLY.
Do not attempt to operate
this machine at maximum
power until you are totally
familiar with its characteris-
tics.
2. THIS MACHINE IS
DESIGNED TO BE RIDDEN
BY THE OPERATOR ONLY.
Do not carry passengers on
this machine.
3. ALWAYS WEAR PROTEC-
TIVE APPAREL.
When operating this
machine, always wear an
approved helmet with gog-
gles or a face shield. Also
wear heavy boots, gloves,
and protective clothing.
Always wear proper fitting
clothing that will not be
caught in any of the moving
parts or controls of the
machine.
4. ALWAYS MAINTAIN YOUR
MACHINE IN PROPER
WORKING ORDER.
For safety and reliability,
the machine must be pro-
erly maintained. Always
perform the pre-operation
checks indicated in this
manual. Correcting a
mechanical problem before
you ride may prevent an
accident.
5. GASOLINE IS HIGHLY
FLAMMABLE.
Always turn off the engine
while refueling. Take care
to not spill any gasoline on
the engine or exhaust sys-
tem. Never refuel in the
vicinity of an open flame, or
while smoking.
SAFETY INFORMATION
NOTICE
IMPORTANTE
CETTE MACHINE EST STRICTE-
MENT DESTINEE A LA COMPETI-
TION, UNIQUEMENT SUR CIRCUIT
FERME. Il est illégal d’utiliser cette
machine sur une rue, route ou artère
publique. L’utilisation de tous-terrains
sur les domaines publics peut également
être illégale. Prière de vérifier les lois
locales avant de conduire.
1. CETTE MACHINE NE DOIT
ETRE UTILISEE QUE PAR
UN CONDUCTEUR EXPERI-
MENTE.
Ne pas essayer d’utiliser cette
machine à sa puissance maxi-
mum tant que vous n’êtes pas
familier avec ses caractéristi-
ques.
2. CETTE MACHINE N’EST
CONCUE POUR ETRE UTI-
LISEE QUE PAR LE CON-
DUCTEUR.
Ne pas prendre de passagers
sur cette machine.
3. TOUJOURS PORTER UN
EQUIPEMENT DE PROTEC-
TION.
Lors de l’utilisation de cette
machine, toujours porter un
casque homologué avec des
lunettes ou un protège-visage.
Porter également de grosses
bottes, des gants et des vête-
ments de protection. Toujours
porter des vêtements de taille
correcte qui ne seront pas pris
dans une des pièces ou com-
mandes mobiles de la machine.
4. TOUJOURS GARDER
VOTRE MACHINE EN BON
ETAT DE MARCHE.
La machine doit être correcte-
ment entretenue pour des
questions de sécurité et de fia-
bilité. Toujours effectuer les
opérations précédant l’utilisa-
tion indiquées dans ce manuel.
La correction d’un problème
mécanique avant la conduite
peut empêcher un éventuel
accident.
5. L’ESSENCE EST HAUTE-
MENT INFLAMMABLE.
Toujours arrêter le moteur en
faisant le plein. Faire attention
à ne pas verser d’essence sur le
moteur ou le pot d’échappe-
ment. Ne jamais faire le plein
au voisinage d’une flamme une
ou en fumant.
INFORMATION DE SECURITE

E0A0000
CONTENTS
CHAPTER 1
GENERAL
INFORMATION
DESCRIPTION............................ 1-1
MACHINE IDENTIFICATION...... 1-3
IMPORTANT INFORMATION..... 1-5
CHECKING OF CONNECTION... 1-9
SPECIAL TOOLS...................... 1-11
CONTROL FUNCTIONS........... 1-27
FUEL......................................... 1-35
STARTING AND BREAK-IN..... 1-37
TORQUE-CHECK POINTS....... 1-45
CLEANING AND STORAGE..... 1-51
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS.... 2-1
MAINTENANCE
SPECIFICATIONS....................... 2-4
GENERAL TORQUE
SPECIFICATIONS..................... 2-19
DEFINITION OF UNITS............. 2-19
CABLE ROUTING DIAGRAM... 2-97
CHAPTER 3
REGULAR
INSPECTION AND
ADJUSTMENTS
MAINTENANCE INTERVALS..... 3-1
PRE-OPERATION INSPECTION
AND MAINTENANCE................ 3-16
ENGINE..................................... 3-21
CHASSIS................................... 3-65
ELECTRICAL.......................... 3-107
TABLES DES
MATIERES
CHAPITRE 1
RENSEIGNEMENTSG
ENERAUX
DESCRIPTION................................ 1-1
IDENTIFICATION DE LA
MACHINE........................................ 1-3
INFORMATIONS
IMPORTANTES.............................. 1-5
VERIFICATION DES
CONNEXIONS................................ 1-9
OUTILS SPECIAUX..................... 1-14
FONCTIONS DES
COMMANDES.............................. 1-27
CARBURANT................................ 1-35
MISE EN MARCHE ET
RODAGE........................................ 1-37
POINTS DE VERIFICATION
DE COUPLE DE SERRAGE....... 1-46
NETTOYAGE ET
RANGEMENT............................... 1-51
CHAPITRE 2
CARACTERISTIQUES
CARACTERISTIQUES
GENERALES................................. 2-20
CARACTERISTIQUES
D’ENTRETIEN.............................. 2-23
CARACTERISTIQUES
GENERALES DE COUPLE......... 2-38
DEFINITION DES UNITES......... 2-38
CHEMINEMENT DES
CABLES......................................... 2-98
CHAPITRE 3
CONTROLES ET
REGLAGES
COURANTS
PROGRAMME D’ENTRETIEN... 3-4
CONTROLE ET ENTRETIEN
AVANT UTILISATION................ 3-17
MOTEUR....................................... 3-21
PARTIE CYCLE........................... 3-65
PARTIE ELECTRIQUE............. 3-107

1 - 12
GEN
INFO
SPECIAL TOOLS
YU-3112-C, 90890-03112 Pocket tester
Use this tool to inspect the coil resistance, output
voltage and amperage.
YU-8036-B
90890-03113Inductive tachometer
Engine tachometer
This tool is needed for observing engine rpm.
YM-33277-A, 90890-03141 Timing light
This tool is necessary for checking ignition timing.
YM-4019, 90890-04019 Valve spring compressor
This tool is needed to remove and install the valve
assemblies.
YM-91042, 90890-04086 Clutch holding tool
This tool is used to hold the clutch when removing or
installing the clutch boss securing nut.
YM-4111, 90890-04111
YM-4116, 90890-04116Valve guide remover
Intake 4.0 mm (0.16 in)
Exhaust 4.5 mm (0.18 in)
This tool is needed to remove and install the valve
guide.
YM-4112, 90890-04112
YM-4117, 90890-04117Valve guide installer
Intake 4.0 mm (0.16 in)
Exhaust 4.5 mm (0.18 in)
This tool is needed to install the valve guide.
YM-4113, 90890-04113
YM-4118, 90890-04118Valve guide reamer
Intake 4.0 mm (0.16 in)
Exhaust 4.5 mm (0.18 in)
This tool is needed to rebore the new valve guide.
YM-04141, 90890-04141 Rotor puller
This tool is used to remove the flywheel magneto.
Part number Tool name/How to use Illustration

1 - 37
GEN
INFO
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 oper-
ate the machine in a well-venti-
lated area.
CAUTION:
The carburetor on this machine
has a built-in accelerator pump.
Therefore, when starting the
engine, do not operate the throt-
tle 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 CLEAN-
ING” 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 starting.)
STARTING A COLD ENGINE
NOTE:This model is equipped with an igni-
tion circuit cut-off system. The
engine can be started under the fol-
lowing conditions.
When the transmission is in neu-
tral.
When the clutch is disengaged
with the transmission in any posi-
tion. However, it is recommended
to shift into neutral before starting
the engine.
MISE EN MARCHE ET
RODAGE
AVERTISSEMENT
Ne jamais mettre le moteur en marche
dans un endroit clos. Les gaz d’échap-
pement sont nocifs et peuvent causer
une perte de conscience et même la
mort en quelques minutes. Toujours
faire marcher le moteur dans un
endroit bien ventilé.
ATTENTION:
Le carburateur de cette machine est
équipé d’une pompe d’accélération.
Il faut donc éviter d’actionner
l’accélérateur au moment de la mise
en marche du moteur, sous peine
d’encrasser la bougie.
Comme pour tous les quatre temps,
il ne faut pas actionner l’accéléra-
teur au moment d’actionner le kick,
sinon celui-ci risque de se relever
brutalement. De plus, l’ouverture
des gaz risque d’appauvrir à l’excès
le mélange air/carburant, ce qui
rendrait la mise en marche difficile.
Avant la mise en marche, effectuer
les vérifications indiquées dans la
liste de contrôle avant utilisation.
ENTRETIEN DU FILTRE A AIR
Comme indiqué dans “NETTOYAGE
DU FILTRE A AIR” au CHAPITRE 3,
appliquer de l’huile de filtre à air en
mousse ou une huile équivalente sur
l’élément. (L’excès d’huile peut empê-
cher le moteur de démarrer correcte-
ment).
MISE EN MARCHE D’UN MOTEUR
FROID
N.B.:
Cette machine est équipée d’un système
de coupure du circuit d’allumage. Les
conditions suivantes doivent être rem-
plies pour que le moteur puisse être mis
en marche.
La machine doit être au point mort.
L’embrayage doit être désengagé et
une vitesse quelconque sélectionnée.
Il est toutefois recommandé de passer
au point mort avant de mettre la
machine en marche.
STARTING AND BREAK-IN
MISE EN MARCHE ET RODAGE

1 - 43
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 switch. 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 min-
utes.
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 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, CAM-
SHAFTS AND GEARS:
These parts require about 30
minutes of break-in operation at
half-throttle or less. Observe the
condition of the engine carefully
during operation.PROCEDURE DE RODAGE
1. Avant de mettre le moteur en mar-
che, faire le plein d’essence.
2. Effectuer les contrôles avant utilisa-
tion de la machine.
3. Lancer le moteur et le laisser se
réchauffer. Vérifier le régime de
ralenti, le fonctionnement des com-
mandes et l’efficacité du coupe-cir-
cuit. Remettre ensuite le moteur en
marche et vérifier son fonctionne-
ment dans les 5 minutes maximum.
4. Piloter la machine sur les rapports
inférieurs et à régime modéré durant
les cinq à huit premières minutes.
5. Vérifier le fonctionnement du
moteur en roulant pendant environ 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. 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 ET PIGNONS:
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.
STARTING AND BREAK-IN
MISE EN MARCHE ET RODAGE

1 - 45
GEN
INFO
TORQUE-CHECK POINTS
Frame construction Frame to rear frame
Combined seat and fuel tank Fuel tank to frame
Exhaust system Silencer to rear frame
Engine mounting Frame to engine
Engine bracket to engine
Engine bracket to frame
Steering Steering stem to handlebar Steering stem to frame
Steering stem to upper bracket
Upper bracket to handlebar
Suspension Front Steering stem to front fork Front fork to upper bracket
Front fork to lower bracket
Rear For link type Assembly of links
Link to frame
Link to rear shock absorber
Link to swingarm
Rear Installation of rear
shock absorberRear shock absorber to frame
Rear Installation of swingarm Tightening of pivot shaft
Wheel Installation of wheel Front Tightening of wheel axle
Tightening of axle holder
Rear Tightening of wheel axle
Wheel to rear wheel sprocket
Brake Front Brake caliper to front fork
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to handlebar
Tightening of bleed screw
Rear Brake pedal to frame
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to frame
Tightening of bleed screw
Fuel system Fuel tank to fuel cock
Lubrication system Tightening of oil hose clamp
NOTE:Concerning the tightening torque, refer to
“MAINTENANCE SPECIFICATIONS” sec-
tion in the CHAPTER 2.
TORQUE-CHECK POINTS

3 - 1
INSP
ADJ
MAINTENANCE INTERVALS
EC300000
REGULAR INSPECTION AND ADJUSTMENTS
MAINTENANCE INTERVALS
The following schedule is intended as a general guide to maintenance and lubrication. Bear in mind that such factors as
weather, terrain, geographical location, and individual usage will alter the required maintenance and lubrication intervals. If
you are a doubt as to what intervals to follow in maintaining and lubricating your machine, consult your Yamaha dealer.
ItemAfter
break-inEvery
race
Every third
(or
500 km)Every fifth
(or
1,000 km)As
requiredRemarks
ENGINE OIL
Replace
Inspect
VALVES
Check the valve clearances The engine must be cold.
Check the valve seats and
valve stems for wear. Inspect
Replace
VALVE SPRINGS
InspectCheck the free length and
the tilt.
Replace
VALVE LIFTERS
InspectCheck for scratches and
wear.
Replace
CAMSHAFTSInspect the camshaft
surface.
Inspect the decompression
system. Inspect
Replace
TIMING CHAIN SPROCKETS, TIMING
CHAIN
InspectCheck for wear on the teeth
and for damage.
Replace
PISTON
InspectInspect crack
Inspect carbon deposits and
eliminate them. Clean
Replace
PISTON RING
InspectCheck ring end gap
Replace
PISTON PIN
Inspect
Replace
CYLINDER HEADInspect carbon deposits and
eliminate them.
Change gasket Inspect and clean
CYLINDER
Inspect and clean Inspect score marks
Inspect wear
Replace
CLUTCH
Inspect and adjust Inspect housing, friction
plate, clutch plate and spring
Replace
TRANSMISSION
Inspect
Replace bearing
SHIFT FORK, SHIFT CAM, GUIDE BAR
InspectInspect wear

3 - 16
INSP
ADJ
PRE-OPERATION INSPECTION AND MAINTENANCE
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator cap.
Check the cooling system for leakage.P.3-21 ~ 29
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-35
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-39 ~ 47
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-29 ~ 31
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-31 ~ 33
Brakes Check the play of front brake and effect of front and rear brake. P.3-65 ~ 77
Drive chainCheck drive chain slack and alignment. Check that the drive
chain is lubricated properly.P.3-79 ~ 83
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-99 ~ 101
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-101 ~ 103
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-83 ~ 97
Cables (wires)Check that the clutch and throttle cables move smoothly. Check
that they are not caught when the handlebars are turned or when
the front forks travel up and down.—
Exhaust pipeCheck that the exhaust pipe is tightly mounted and has no
cracks.P.4-7 ~ 11
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-77
Lubrication Check for smooth operation. Lubricate if necessary. P.3-105
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-45
Lead connectorsCheck that the AC magneto, CDI unit, and ignition coil are
connected tightly.P.1-9
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs
before racing? Are inspection and maintenance completely
done?P.7-1 ~ 42