2004 YAMAHA YZ250F ECU

ZUR BEACHTUNG
Dieses Motorrad ist ausschließlich
für den Einsatz im Gelände-Renn-
sport auf geschlossenen Kursen
bestimmt. Die Benutzung dieses
Fahrzeugs auf öffentlichen Straßen
verstößt gegen die Straßenverkehrs-
ordnung. Aber auch Fahrten auf
öffentlichem Gelände können wal-
tende Verkehrsbestimmungen verlet-
zen. Erkundigen Sie sich deshalb vor
der Fahrt bei der zuständigen Ver-
kehrsbehörde.
1. Die Benutzung dieses
Motorrads setzt einegewisse Erfahrung voraus.Fahren Sie diese Maschine
nicht voll aus, bevor Sie
sich mit allen ihren Eigen-
schaften gründlich vertraut
gemacht haben.
2. Dieses Motorrad ist aus-
schließlich für Solofahrtenbestimmt.Führen Sie niemals einen
Sozius auf dieser Maschine
mit.
3. Geeignete Schutzkleidung
ist obligatorisch.Fahren Sie stets mit ange-
messener Schutzkleidung,
robusten Stiefeln, speziellen
Motorrad-Handschuhen,
einem geprüften, perfekt sit-
zenden Helm und ausrei-
chendem Augenschutz.
Achten Sie darauf, daß die
Kleidung eng anliegt und
nicht mit beweglichen Tei-
len oder Bedienungselemen-
ten der Maschine in
Berührung kommt.
4. Regelmäßige Pflege und
Wartung sind unerläßlich.
Nur vorschriftsmäßige War-
tung, regelmäßige Schmie-
rung und korrekte
Einstellung können opti-
male Leistung und Sicher-
heit gewährleisten.
Um Unfälle zu vermeiden,
stets die in dieser Anlei-
tung aufgeführte “Routine-
kontrolle vor Fahrtbeginn”
durchführen.
5. Benzin ist äußerst entzünd-
bar und u. U. explosiv.Stellen Sie vor dem Tanken
immer den Motor ab und
achten Sie darauf, daß kein
Benzin auf den Motor oder
die Auspuffanlage ver-
schüttet wird. Während des
Tankens offene Flammen
und Funken fernhalten und
keinesfalls rauchen.
SICHERHEITSTINFORMATION

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 caractéristiques.
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 ques-
tions de sécurité et de fiabilité.
Toujours effectuer les opérations
précédant l’utilisation 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

COMUNICAZIONE
IMPORTANTE
QUESTO VEICOLO È STATO PRO-
GETTATO ESCLUSIVAMENTE PER
LE COMPETIZIONI SU CIRCUITI
CHIUSI. L’impiego di questo veicolo su
strade pubbliche o autostrade è illegale.
L’impiego fuoristrada su terreni pubblici
potrebbe essere egualmente illegale.
Verificare la normativa locale prima di
mettersi alla guida.
1. L’IMPIEGO DI QUESTO
VEICOLO È LIMITATO
ESCLUSIVAMENTE A
PILOTI ESPERTI.
Non tentare di far funzionare
questo veicolo al massimo
numero di giri finché non si è
acquisita una familiarità totale
con le sue caratteristiche.
2. QUESTO VEICOLO È
STATO PROGETTATO PER
ESSERE GUIDATO ESCLU-
SIVAMENTE DA UN UNICO
PILOTA.
Non è consentito il trasporto di
passeggeri su questo veicolo.
3. INDOSSARE SEMPRE GLI
INDUMENTI DI PROTE-
ZIONE.
Durante l’impiego di questo
veicolo, indossare sempre un
casco omologato con relativi
occhiali protettivi o visiera.
Indossare inoltre stivali e
guanti resistenti nonché indu-
menti di protezione. Indossare
sempre indumenti aderenti in
modo tale che non possano
restare intrappolati nelle parti
in movimento o nei comandi
del veicolo.
4. MANTENERE SEMPRE IL
VEICOLO IN BUONE CON-
DIZIONI OPERATIVE.
Per la sicurezza e l’affidabilità,
il veicolo va manutenuto cor-
rettamente. Eseguire sempre i
controlli preliminari indicati
in questo manuale. Correggere
ogni eventuale problema mec-
canico prima di mettersi alla
guida onde evitare incidenti.
5. LA BENZINA È ALTA-
MENTE INFIAMMABILE.
Spegnere sempre il motore
durante il rifornimento. Fare
attenzione a non far cadere
benzina sul motore o sul sistema
di scarico. Non effettuare il
rifornimento in prossimità di
fiamme vive o mentre si fuma.
INFORMAZIONI DISICUREZZA

6. GASOLINE CAN CAUSE INJURY.
If you should swallow some gasoline,
inhale excess gasoline vapors, or
allow any gasoline to get into your
eyes, contact a doctor immediately. If
any gasoline spills onto your skin or
clothing, immediately wash skin areas
with soap and water, and change your
clothes.
7. ONLY OPERATE THE MACHINE IN AN
AREA WITH ADEQUATE VENTILA-
TION.
Never start the engine or let it run for
any length of time in an enclosed area.
Exhaust fumes are poisonous. These
fumes contain carbon monoxide,
which by itself is odorless and color-
less. Carbon monoxide is a dangerous
gas which can cause unconscious-
ness or can be lethal.
8. PARK THE MACHINE CAREFULLY;
TURN OFF THE ENGINE.
Always turn off the engine if you are
going to leave the machine. Do not
park the machine on a slope or soft
ground as it may fall over.
9. THE ENGINE, EXHAUST PIPE, MUF-
FLER, AND OIL TANK WILL BE VERY
HOT AFTER THE ENGINE HAS BEEN
RUN.
Be careful not to touch them or to
allow any clothing item to contact
them during inspection or repair.
10. PROPERLY SECURE THE MACHINE
BEFORE TRANSPORTING IT.
When transporting the machine in
another vehicle, always be sure it is
properly secured and in an upright
position and that the fuel cock is in
the “OFF” position. Otherwise, fuel
may leak out of the carburetor or fuel
tank.

COMMENT UTILISER
CE MANUEL
INFORMATIONS PARTI-
CULIEREMENT IMPOR-
TANTES
Le symbole d’alerte de sécurité signifie
ATTENTION! SOYEZ VIGILANT!
VOTRE SECURITE EST EN JEU!
Le non-respect des instructions AVER-
TISSEMENT peut entraîner de sérieuses
blessures ou la mort au pilote de la
machine, à un passant ou à une personne
inspectant ou réparant la machine.
Un ATTENTION indique les procédures
spéciales qui doivent être suivies pour
éviter d’endommager la machine.
N.B.:
Un N.B. fournit les renseignements
nécessaires pour rendre les procédures
plus faciles ou plus claires.
AVERTISSEMENT
ATTENTION:
TROUVER LA PAGE RECHER-
CHEE
1. Ce manuel comprend 7 chapitres:
“Renseignements généraux”,
“Caractéristiques”, “Controles et
réglages courants”, “Moteur”, “Par-
tie cycle”, “Partie électrique” et
“Mise au point”.
2. La table des matières se trouve au
début du manuel.
Regarder la disposition générale du
manuel avant de recherche le chapi-
tre et l’article désirés.
Arquer le manuel à son bord, de la
manière indiquée, pour trouver le
symbole de devant désiré et passer à
une page de la description et l’arti-
cle désirés.

BENUTZERHINWEISE
KENNZEICHNUNG WICH-
TIGER HINWEISE
Das Ausrufezeichen bedeutet:
“GEFAHR! Achten Sie auf Ihre
Sicherheit!”
Ein Mißachten dieser Warnhinweise
bringt Fahrer, Mechaniker und
andere Personen in Verletzungs-
oder Lebensgefahr.
Hierunter sind Vorsichtsmaßnah-
men zum Schutz des Fahrzeugs vor
Schäden aufgeführt.
HINWEIS:
Ein HINWEIS gibt Zusatzinformatio-
nen und Tips, um bestimmte Vor-
gänge oder Arbeiten zu
vereinfachen.
WARNUNG
ACHTUNG:
INFORMATION AUFFINDEN
1. Diese Anleitung umfaßt sieben
Kapitel: 1. Allgemeine Angaben
– 2. Technische Daten – 3.
Regelmässige Inspektion und
Einstellarbeiten – 4. Motor – 5.
Fahrwerk – 6. Elektrische
Anlage – 7. Abstimmung
2. Dem ersten Kapitel geht ein
Inhaltverzeichnis voran. Machen
Sie sich mit dem Inhalt und Auf-
bau der Anleitung vertraut, bevor
Sie nach bestimmten Angaben
suchen. Halten Sie das Buch wie
in der Abbildung gezeigt, um das
Auffinden der einzelnen Kapitel
zu erleichtern.

COME UTILIZZARE
QUESTO MANUALE
INFORMAZIONI PARTI-
COLARMENTE IMPOR-
TANTI
Questo simbolo segnala un pericolo che
richiede la MASSIMA ATTENZIONE!
PERICOLO! LA SICUREZZA DELLE
PERSONE È COINVOLTA!
Il mancato rispetto del richiamo di
AVVERTENZA può comportare gravi
lesioni personali o il decesso del pilota,
di persone presenti nelle vicinanze o di
coloro che controllano o riparano il vei-
colo.
Un richiamo di ATTENZIONE indica la
necessità di speciali precauzioni da pren-
dere per evitare danni materiali al vei-
colo.
NOTA:
Una NOTA fornisce informazioni utili
per rendere meglio comprensibili le pro-
cedure e per facilitarne l’esecuzione.
AVVERTENZA
ATTENZIONE:
COME TROVARE LA PAGINA
RICHIESTA
1. Questo manuale consta di sette capi-
toli: “Informazioni generali”, “Spe-
cifiche”, “Ispezioni e registrazioni
regolari”, “Motore”, “Parte cicli-
stica”, “Impianto elettrica” e
“Messa a punto”.
2. L’indice si trova all’inizio del
manuale. Dare uno sguardo alla
struttura del manuale prima di cer-
care il capitolo e l’argomento richie-
sti.
Piegare il libro sul bordo, come illu-
strato, per trovare il riferimento
simbolico del bordo anteriore e
andare alla pagina per l’argomento e
la descrizione richiesti.

GEN
INFO
1 - 7
SPECIAL TOOLS
SPECIAL TOOLS
The proper special tools are necessary for complete and accurate tune-up and assembly. Using the
correct special tool will help prevent damage caused by the use of improper tools or improvised
techniques. The shape and part number used for the special tool differ by country, so two types are
provided. Refer to the list provided to avoid errors when placing an order.
NOTE:
For U.S.A. and Canada, use part number starting with “YM-”, “YU-” or “ACC-”.
For others, use part number starting with “90890-”.
Part number Tool name/How to use Illustration
YU-1135-A, 90890-01135 Crankcase separating tool
These tool is used to remove the crankshaft from
either case.YU-1135-A 90890-01135
YM-1189, 90890-01189 Flywheel puller
This tool is used to remove the flywheel magneto.YM-1189 90890-01189
YU-1235, 90890-01235 Rotor holding tool
This tool is used when loosening or tightening the fly-
wheel magneto securing nut.YU-1235 90890-01235
YU-3097, 90890-01252
YU-1256Dial gauge and stand
Stand
These tools are used to check each part for runout or
bent.YU-3097
YU-125690890-01252
YU-90050, 90890-01274
YU-90050, 90890-01275
YU-91044, 90890-04081
YU-90063, 90890-01278Crankshaft installing tool
Crankshaft installing pot
Crankshaft installing bolt
Spacer (crankshaft installer)
Adapter (M12)
These tools are used to install the crankshaft.YU-90050
YU-90063
YU-9104490890-01274
90890-01275
90890-01278
90890-04081
YU-1304, 90890-01304 Piston pin puller set
This tool is used to remove the piston pin.YU-1304 90890-01304
YU-24460-01, 90890-01325
YU-33984, 90890-01352Radiator cap tester
Radiator cap tester adapter
These tools are used for checking the cooling sys-
tem.YU-24460-01
YU-3398490890-01325
90890-01352

GEN
INFO
1 - 8
SPECIAL TOOLS
YU-33975, 90890-01403 Steering nut wrench
This tool is used when tighten the steering ring nut to
specification.YU-33975 90890-01403
YM-01442, 90890-01442 Fork seal driver
This tool is used when install the fork oil seal.YM-01442 90890-01442
YM-01494, 90890-01494 Damper rod holder
Use this tool to remove and install the damper rod.YM-01494 90890-01494
YU-3112-C, 90890-03112 Pocket tester
Use this tool to inspect the coil resistance, output
voltage and amperage.YU-3112-C 90890-03112
YM-33277-A, 90890-03141 Timing light
This tool is necessary for checking ignition timing.YM-33277-A 90890-03141
YM-4019, 90890-04019 Valve spring compressor
This tool is needed to remove and install the valve
assemblies.YM-4019 90890-04019
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-91042 90890-04086
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-4111
YM-411690890-04111
90890-04116
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-4112
YM-411790890-04112
90890-04117
Part number Tool name/How to use Illustration

1 - 19
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.

4 - 40
ENGVALVES AND VALVE SPRINGS
ASSEMBLY AND INSTALLATION
Valve and valve spring
1. Apply:
Molybdenum disulfide oil
Onto the valve stem and valve stem
seal.
2. Install:
Valve 1
Valve spring seat 2
Valve stem seal 3
Valve spring 4
Valve spring retainer 5
To cylinder head.
NOTE:
Make sure that each valve is installed in its
original place, also referring to the painted
color as follows.
Intake (middle) a: yellow
Intake (right/left) b: white
Exhaust: no paint
Install the valve springs with the larger pitch
c facing upward.
dSmaller pitch
3. Install:
Valve cotter
NOTE:
While compressing the valve spring with a
valve spring compressor 1 install the valve
cotters.
4. To secure the valve cotters onto the
valve stem, lightly tap the valve tip with a
piece of wood.
CAUTION:
Hitting the valve tip with excessive force
could damage the valve.
Valve spring compressor:
YM-4019/90890-04019

4 - 82
ENGENGINE REMOVAL
EC4M0000
ENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the frame.
WARNINGSupport the machine securely so there is no
danger of it falling over.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Radiator Refer to “RADIATOR” section.
Shift pedal Refer to “KICK SHAFT AND SHIFT
SHAFT” section.
Cylinder head breather hose and
oil tank breather hoseRefer to “CAMSHAFTS” section.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.