2003 YAMAHA YZ250F diagram

EC083000
MANUAL FORMAT
All of the procedures in this manual are organized in a sequential, step-by-step format. The informa-
tion has been complied to provide the mechanic with an easy to read, handy reference that contains
comprehensive explanations of all disassembly, repair, assembly, and inspection operations.
In this revised format, the condition of a faulty component will precede an arrow symbol and the
course of action required will follow the symbol, e.g.,

Bearings
Pitting/damage
→
Replace.
EC084002
HOW TO READ DESCRIPTIONS
To help identify parts and clarify procedure steps, there are exploded diagrams at the start of each
removal and disassembly section.
1. An easy-to-see exploded diagram
1
is provided for removal and disassembly jobs.
2. Numbers
2
are given in the order of the jobs in the exploded diagram. A number that is
enclosed by a circle indicates a disassembly step.
3. An explanation of jobs and notes is presented in an easy-to-read way by the use of symbol
marks
3
. The meanings of the symbol marks are given on the next page.
4. A job instruction chart
4
accompanies the exploded diagram, providing the order of jobs,
names of parts, notes in jobs, etc.
5. Extent of removal
5
is provided in the job instruction chart to save the trouble of an unneces-
sary removal job.
6. For jobs requiring more information, the step-by-step format supplements
6
are given in addi-
tion to the exploded diagram and job instruction chart.

AUFBAU
Diese Anleitung wurde zusammen-
gestellt, um dem Benutzer ein leicht
verständliches Nachschlagewerk in
die Hand zu geben, in dem alle dar-
gestellten Arbeitsvorgänge (Ein- und
Ausbau, Zerlegung und Zusammen-
bau, Prüfung und Reparatur) detail-
liert und in der entsprechenden
Reihenfolge beschrieben sind.
Je nach Zustand eines fehlerhaften
Bauteils weist ein Pfeilsymbol auf die
erforderliche Maßnahme hin. Bei-
spiel:

Lager
Pitting/Beschädigung
→
Erneuern.
LESEN DER BESCHREIBUNGEN
Um bei der Identifikation der Teile zu
helfen und die Arbeitsschritte zu ver-
deutlichen, sind Explosionsdia-
gramme am Beginn jedes Ausbau-
und Demontageabschnittes darge-
stellt.
1. Für die Ausbau- und Demonta-
gearbeiten ist meistens ein über-
sichtliches Explosionsdiagramm
1
dargestellt.
2. Die Nummern
2
in dem Explosi-
onsdiagramm sind in der Rei-
henfolge der Arbeiten
aufgeführt. Eine in einen Kreis
eingeschriebene Nummer
bezeichnet einen Demontage-
schritt.
3. Eine Erläuterung der Arbeiten
und Hinweise ist durch ablese-
freundliche Symbolmarkierun-
gen
3
gegeben. Die
Bedeutungen der Symbolmar-
kierungen sind auf der nächsten
Seite aufgeführt.
4. Eine Arbeitsanweisungstabelle
4
begleitet das Explosionsdia-
gramm und gibt die Arbeitsrei-
henfolge, Bezeichnung der
Teile, Hinweise zu den Arbeiten
usw. an.
5. Der Umfang des Ausbaus
5
ist
in der Arbeitsanweisungstabelle
aufgeführt, um nicht erforderli-
che Ausbauarbeiten zu vermei-
den.
6. Für Arbeiten, für die weitere
Informationen benötigt werden,
sind schrittweise Ergänzungen
6
zusätzlich zu dem Explosi-
onsdiagramm und der Arbeitsan-
weisungstabelle aufgeführt.
FORMAT DU MANUEL
Dans ce manuel, toutes les procédures
sont décrites pas à pas. Les informations
ont été condensées pour fournir au méca-
nicien un guide pratique et facile à lire,
contenant des explications claires pour
toutes les procédures de démontage,
réparation, remontage et vérification.
Dans ce nouveau format, l’état d’un
composant défectueux est suivi d’une
flèche qui indique les mesures à prendre.
Exemple:

Roulements
Piqûres/endommagement
→
Rempla-
cer.
COMMENT LIRE LES DESCRIP-
TIONS
Chaque section détaillant des étapes de
démontage ou de remontage est précédée
de vues en éclaté qui permettent de clari-
fier ces opérations.
1. Exemple de vue en éclaté
1
clari-
fiant les opérations de démontage et
de remontage.
2. Sur les vues en éclaté, les pièces
sont numérotées
2
dans l’ordre des
opérations à effectuer. Un chiffre
entouré d’un cercle correspond à
une étape de démontage.
3. Les vues en éclaté portent égale-
ment des symboles
3
qui rappellent
des points importants à ne pas
oublier. La signification de ces sym-
boles est expliquée à la page sui-
vante.
4. Les vues en éclaté sont suivies d’un
tableau
4
fournissant l’ordre des
opérations, le nom des pièces, des
remarques, etc.
5. Pour éviter la dépose superflue de
pièces, l’étendue de la dépose
5
est
indiquée dans le tableau de descrip-
tion du travail.
6. Pour les travaux qui demandent des
explications supplémentaires, la vue
en éclaté et le tableau sont suivis
d’une description détaillée
6
des
opérations.
STRUTTURA DEL
MANUALE
Tutte le procedure di questo manuale
sono organizzate in sequenze passo a
passo. Le informazioni sono state redatte
in modo tale da fornire al meccanico un
riferimento comodo e di agevole lettura
che comprenda, al contempo, spiega-
zioni complete relative alle operazioni di
smontaggio, riparazione, montaggio ed
ispezione.
In questo nuovo formato, la condizione
di un componente non funzionante pre-
cede una freccia e l’azione richiesta
segue il simbolo., ad es.:

Cuscinetti
Puntinatura/danno
→
Sostituire.
COME LEGGERE LE DESCRI-
ZIONI
Allo scopo di agevolare l’identificazione
dei pezzi e di chiarire le fasi delle varie
procedure, sono state inserite rappresen-
tazioni esplose all’inizio di ciascun para-
grafo dedicato alla rimozione e allo
smontaggio.
1. Una rappresentazione esplosa di
immediata comprensione
1
viene
fornita per agevolare le operazioni
di rimozione e smontaggio.
2. I numeri
2
sono indicati nella rap-
presentazione esplosa secondo la
sequenza di lavoro. Un numero rac-
chiuso in un cerchietto indica una
fase di un’operazione di smontag-
gio.
3. Una spiegazione delle operazioni e
delle note viene illustrata in maniera
chiara dall’impiego di riferimenti
simbolici
3
. Il significato dei riferi-
menti simbolici viene fornito alla
pagina seguente.
4. Uno schema di istruzioni di lavoro
4
unitamente alla rappresenta-
zione esplosa, fornisce la sequenza
dei lavori, i nomi dei pezzi, le note
relative ai lavori, ecc.
5. L’indicazione relativa alla portata
dell’intervento di rimozione
5
viene fornita nello schema di istru-
zioni per evitare operazioni di rimo-
zione non necessaire.
6. Per quegli interventi che richiedono
maggiori informazioni, vengono
forniti supplementi in formato passo
a passo
6
oltre alla rappresenta-
zione esplosa e allo schema di istru-
zioni.

ILLUSTRATED SYMBOLS
(Refer to the illustration)
Illustrated symbols
1
to
7
are designed as
thumb tabs to indicate the chapter’s number
and content.
1
General information
2
Specifications
3
Regular inspection and adjustments
4
Engine
5
Chassis
6
Electrical
7
Tuning
Illustrated symbols
8
to
D
are used to identify
the specifications appearing in the text.
8
With engine mounted
9
Special tool
0
Filling fluid
A
Lubricant
B
Tightening
C
Specified value, Service limit
D
Resistance (
Ω
), Voltage (V), Electric current (A)
Illustrated symbols
E
to
H
in the exploded
diagrams indicate grade of lubricant and loca-
tion of lubrication point.
E
Apply engine oil
F
Apply molybdenum disulfide oil
G
Apply lightweight lithium-soap base grease
H
Apply molybdenum disulfide grease
Illustrated symbols
I
to
J
in the exploded
diagrams indicate where to apply a locking
agent and where to install new parts.
IApply locking agent (LOCTITE®)
JUse new one 12
34
56
78
90
AB
CD
EF
GH
IJ
GEN
INFOSPEC
INSP
ADJENG
CHAS–+ELEC
TUN
T R..
EM
BM

EC0A0000
CONTENTS
CHAPTER 1
GENERAL INFORMATION
DESCRIPTION .......................................... 1-1
MACHINE IDENTIFICATION .................... 1-2
IMPORTANT INFORMATION ................... 1-3
CHECKING OF CONNECTION ................ 1-6
SPECIAL TOOLS ...................................... 1-7
CONTROL FUNCTIONS ......................... 1-10
FUEL ....................................................... 1-13
STARTING AND BREAK-IN ................... 1-14
TORQUE-CHECK POINTS ..................... 1-18
CLEANING AND STORAGE .................. 1-19
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS .................. 2-1
MAINTENANCE SPECIFICATIONS ......... 2-4
GENERAL TORQUE
SPECIFICATIONS .................................. 2-17
DEFINITION OF UNITS .......................... 2-17
CABLE ROUTING DIAGRAM ................ 2-18
CHAPTER 3
REGULAR INSPECTION AND
ADJUSTMENTS
MAINTENANCE INTERVALS ................... 3-1
PRE-OPERATION INSPECTION
AND MAINTENANCE ............................... 3-4
ENGINE ..................................................... 3-5
CHASSIS ................................................. 3-24
ELECTRICAL .......................................... 3-45

CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS
AND WIRING DIAGRAM .......................... 6-1
MAP-CONTROLLED CDI UNIT ................ 6-2
IGNITION SYSTEM ................................... 6-3
THROTTLE POSITION SENSOR
SYSTEM .................................................... 6-7
CHAPTER 7
TUNING
ENGINE ..................................................... 7-1
CHASSIS ................................................. 7-11

2 - 18
SPECCABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1Fuel tank breather hose
2Clutch cable
3Oil tank breather hose
4Hot starter cable
5Cylinder head breather hose
6Cable guide
7Hose guide
8Brake hose
9Engine stop switch lead
0Clamp
ASub-wire harness
BThrottle position sensor lead
CNeutral switch lead
DOil hose
ECDI magneto lead
FRadiator breather hose
GCarburetor breather hose
HCarburetor overflow hoseÅPass the fuel tank breather hose
between the handlebar and ten-
sion bar, then insert its end into
the hole of the number plate.
ıPass the hot starter cable
between the cylinder head
breather hose, oil tank breather
hose and ignition coil, then on
the outside of the left engine
bracket.
ÇPass the clutch cable through
the cable guides.
ÎPass the clutch cable in front of
the radiator mounting boss.
‰Fit the brake hose into the
guides on the protector.ÏFasten the neutral switch lead
and CDI magneto lead to the
cable guide with a plastic locking
tie and cut off the tie end.
ÌFasten the engine stop switch
lead, neutral switch lead and
CDI magneto lead.
ÓFasten the engine stop switch
lead and sub-wire harness.
ÈFasten the sub-wire harness
and hot starter cable at the white
tape for the sub-wire harness.
ÔFasten the sub-wire harness.
Pass the sub-wire harness
between the engine brackets.

2 - 19
SPECCABLE ROUTING DIAGRAM
ÒMake sure that the throttle
position sensor lead coupler
does not go out side the chas-
sis.
˜Fasten the throttle position
sensor lead.
ˆFasten the neutral switch lead
on the oil hose with a plastic
locking tie and cut off the tie
end.
ØFasten the neutral switch lead.
∏Fasten the neutral switch lead
and CDI magneto lead.
ŒPass the neutral switch lead,
CDI magneto lead and radiator
breather hose between the
radiator and frame.ÂPass the carburetor breather
hoses and overflow hose so
that all there hoses do not con-
tact the rear shock absorber.

2 - 20
SPEC
1CDI unit
2Hot starter cable
3Throttle cable (return)
4Throttle cable (pull)
5Cable guide
6Ignition coil
7Radiator hose 2
8Radiator breather hose
9Radiator hose 4
0CDI unit bracket
ACDI unit bandÅPass the hot starter cable and
throttle cables through the
cable guides.
ıPass the hot starter cable and
throttle cables between the
radiator and frame, then under
the radiator mounting boss.
ÇPass the throttle cables on the
outside of the ignition coil.
ÎPass the radiator breather
hose in front of the radiator
hose 2, on the left of the chas-
sis, and then between the
frame and radiator hose 4.
‰Insert the CDI unit band over
the CDI unit bracket as far as
possible.ÏFirst install the CDI unit and
CDI unit band to the CDI unit
bracket, then the CDI unit
bracket to the frame.
7
8
91
A0
2
3
4 1 Î
ω
Å
ı
Ç B
A
A
B
5
6
CABLE ROUTING DIAGRAM