engine YAMAHA WR 250F 2003 Owners Manual

5 - 91
CHASHANDLEBAR
EC5B0000
HANDLEBAR
Extent of removal:
1 Handlebar removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removal
HANDLEBAR REMOVAL
Headlight
1 Hot starter cable 1 Disconnect at the lever side.
2 Hot starter lever holder 1
3 Clutch cable 1 Disconnect at the lever side.
4 Clutch lever holder 1 Disconnect the clutch switch lead.
5 Engine stop switch 1 Disconnect the engine stop switch lead.
6 Light switch 1
7 Brake master cylinder 1 Refer to “REMOVAL POINTS”.
8 Start switch 1 Disconnect the start switch lead.
9 Throttle cable cap 1
10 Throttle cable #2 (pushed) 1 Disconnect at the throttle side.
11 Throttle cable #1 (pulled) 1 Disconnect at the throttle side.
12 Right grip 1 Refer to “REMOVAL POINTS”.
13 Tube guide 1
14 Grip cap cover 1
15 Left grip 1 Refer to “REMOVAL POINTS”.
16 Handlebar upper holder 2
17 Handlebar 1
1

5 - 101
CHASHANDLEBAR
10. Install:
Engine stop switch
1
Clutch lever holder
2
Bolt (clutch lever holder)
3
Hot starter lever holder
4
Bolt
(hot starter lever holder)
5
Clamp
6
NOTE:The engine stop switch, clutch
lever holder and clamp should be
installed according to the dimen-
sions shown.
Pass the engine stop switch lead in
the middle of the clutch lever
holder.
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
11. Install:
Clutch cable
1
Hot starter cable
2
NOTE:Apply the lithium soap base grease
on the clutch cable end and hot
starter cable end.
12. Adjust:
Clutch lever free play
Refer to “CLUTCH ADJUST-
MENT” section in the CHAP-
TER 3.
Hot starter lever free play
Refer to “HOT STARTER
LEVER ADJUSTMENT” sec-
tion in the CHAPTER 3.
13. Fasten the hot starter cable
1
and clutch cable
2 with a clamp
3.
1
2
3
14. Insert the end of the fuel
breather hose
1 into the hole in
the steering stem cap
2.
1
2
10. Monter:
Coupe-circuit de moteur 1
Support de levier d’embrayage 2
Boulon (support de levier
d’embrayage) 3
Support du levier de démarreur à
chaud 4
Boulon (support du levier de
démarreur à chaud) 5
Bride 6
N.B.:
Le coupe-circuit de moteur, le support
de levier d’embrayage et l’attache en
plastique doivent être installés en res-
pectant les dimensions indiquées.
Faire passer le fil du coupe-circuit de
moteur au centre du support de levier
d’embrayage.
T R..4 Nm (0,4 m · kg, 2,9 ft · lb)
T R..4 Nm (0,4 m · kg, 2,9 ft · lb)
11. Monter:
Câble d’embrayage 1
Câble de démarreur à chaud 2
N.B.:
Enduire de la graisse à base de savon au
lithium sur l’extrémité du câble
d’embrayage, et sur l’extrémité du câble
de démarrage à chaud.
12. Régler:
Jeu du levier d’embrayage
Se reporter à la section “REGLA-
GE DE L’EMBRAYAGE” du
CHAPITRE 3.
Jeu du levier de démarreur à
chaud
Se reporter à la section
“REGLAGE DU LEVIER DE
DEMARREUR A CHAUD” du
CHAPITRE 3.
13. Attacher le câble de démarrage à
chaud 1 et le câble d’embrayage
2 à l’aide d’une bride 3.
14. Insérer l’extrémité de la durit de
mise à l’air du réservoir de carbu-
rant 1 dans le trou du capuchon 2
de la colonne de direction.
GUIDON

5 - 103
CHASSTEERING
EC560000
STEERING
Extent of removal:
1 Lower bracket removal
2 Bearing removal
Extent of removal Order Part name Q’ty Remarks
STEERING REMOVAL
WARNING
Support the machine securely so there is nodanger of it falling over. Preparation for removal Hold the machine by placing the suitable
stand under the engine.
Headlight
Handlebar Refer to “HANDLEBAR” section.
Front brake hose guide
Front fender
1 Coupler bracket 1
2 Trip meter 1
3 Main switch 1 Disconnect the main switch lead.
4 Steering stem cap 1
5 Steering stem nut 1
6 Front fork 2 Refer to “FRONT FORK” section.
7 Upper bracket 1
8 Steering ring nut 1 Use special tool.
Refer to “REMOVAL POINTS”.
9 Lower bracket 1
12

5 - 119
CHASSWINGARM
EC570000
SWINGARM
Extent of removal:
1 Swingarm removal
Extent of removal Order Part name Q’ty Remarks
SWINGARM REMOVAL
WARNING
Support the machine securely so there is nodanger of it falling over. Preparation for removal Hold the machine by placing the suitable
stand under the engine.
Brake hose holder
Refer to “FRONT BRAKE AND REAR BRAKE”
section.
Rear brake caliper
Bolt (brake pedal) Shift the brake pedal backward.
Drive chain
1 Drive chain support 1
2 Lower chain tensioner 1
3 Bolt (rear shock absorber-relay arm) 1 Hold the swingarm.
4 Bolt (connecting rod) 1
5 Pivot shaft 1
6 Swingarm 1
1

5 - 139
CHASREAR SHOCK ABSORBER
EC580000
REAR SHOCK ABSORBER
Extent of removal:
1 Rear shock absorber removal
2 Rear shock absorber disassembly
Extent of removal Order Part name Q’ty Remarks
REAR SHOCK ABSORBER REMOVAL
WARNING
Support the machine securely so there is nodanger of it falling over. Preparation for removal Hold the machine by placing the suitable
stand under the engine.
Seat, fitting band and side covers Refer to “SEAT, FUEL TANK AND SIDE COVERS”
section in the CHAPTER 4.
Air filter case cover Refer to “AIR FILTER CLEANING” section in the
CHAPTER 3.
Silencer Refer to “EXHAUST PIPE AND SILENCER” section
in the CHAPTER 4.
Drain the coolant. Refer to “COOLANT REPLACEMENT” section in the
CHAPTER 3.
Coolant reservoir breather hose Disconnect at the coolant reservoir side.
Coolant reservoir hose Disconnect at the coolant reservoir side.
Battery Refer to “BATTERY INSPECTION AND
CHARGING” section in the CHAPTER 3.
Disconnect the starter relay coupler.
Starter motor lead Disconnect at the starter relay side.

6 - 1
–+ELECELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000ELECTRICAL COMPONENTS
1Headlight
2Engine stop switch
3Clutch switch
4Diode
5Starter relay diode
6Throttle position sensor
7Starter relay
8Fuse
9Starting circuit cut-off relay
0TaillightANeutral switch
BStarter motor
CAC magneto
DRectifier/regulator
EIgnition coil
FSpark plug
GStart switch
HLight switch
IMain switch
JCDI unit
KBatteryCOLOR CODE
B ...................... Black
Br ..................... Brown
Gy .................... Gray
L ...................... Blue
O...................... Orange
R ...................... Red
Sb .................... Sky blue
W ..................... White
Y ...................... YellowB/L ................... Black/Blue
B/W .................. Black/White
L/B ................... Blue/Black
L/R ................... Blue/Red
L/Y ................... Blue/Yellow
L/W .................. Blue/White
R/B................... Red/Black
EC612000WIRING DIAGRAM
1 2345
678
90
A
B CDEFGH
I
J
K
WR
WR
R
BR/BBr
R
BR/BBr
RW
L/RL/BBB
SbL/W
WY
YW
L/YBBB
WY
RYW
R
LY
B
YLB/L
B
B
ON
OFF
10A
BB
OFF
ON
OFF
STARTSTART
R-BrL/W
BLY
YLB-LB
B
BrL/W
BrL/W
L/B-LB
YL
B
L-B
-Sb
B/WBBB
W/RB/W
R/BGyBrL/W
ON
STOP
OB
LYSbB/L
W RBrB/W
L/BGyWR/BO B
L Y SbB/L
B O
L/YSbL/R
R W
Y W
Y W
Y B
B
L
L L
L B
B
B
RRR/B
B Br B
B B B B
L/W
R
R
R R B
R
BrBr
L/W L/W
Br B
L/B
L/B
L/R

Br
R/B
L/B L/W
B/W
W W/RW
RO
L
Y
B/L
O

B
L
Y
B/LSbB/W
B
L/R L/Y L/Y
B
SbSb
BGy
C
HD
BI
5
9
G3 4
A 2J
EF
6 78
1
0K

6 - 3
–+ELECMAP-CONTROLLED CDI UNIT
MAP-CONTROLLED CDI UNIT
A map-controlled, CDI ignition system is used in the WR250F.
The microcomputer in the CDI unit detects the engine speed and throttle position, thus determining the optimum ignition
timing through the entire operating range. In this way, quick throttle response can be achieved according to various riding
conditions.






Function of Component






Principal of 3-Dimensional Control
Conventionally, ignition timing was controlled only by
engine revolutions (2-dimensional control).
However, ignition timing needs advancement also by
engine load. Thus, accurate ignition timing can be deter-
mined by adding throttle opening to determine ignition
timing (3-dimensional control).
3-D Image Map of Ignition Timing
(different from actual characteristics)
Component Function
Throttle position sensor Detects throttle valve opening and inputs it into the computer in the CDI unit as a
throttle opening signal.
Pickup coil Detects signal rotor revolutions and inputs them into the computer in the CDI unit as
engine revolution signals.
CDI unit The signals of the throttle position sensor and pickup coil sensor are analyzed by
the computer in the CDI unit, which then adjusts ignition timing for the operation
requirements.
CDI unit
Throttle position sensor
Pickup coil AC magneto rotorIgnition coil
Revolutions
Ignition timing
Throttle opening

6 - 8
–+ELECIGNITION SYSTEM
EC620000
IGNITION SYSTEM
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning engine being attributable to ignition system failure
and for checking the spark plug which will not spark.
*1 marked: Refer to “FUSE INSPECTION” section in the CHAPTER 3.
*2 marked: Refer to “BATTERY INSPECTION AND CHARGING” section in the CHAPTER 3.
*3 marked: Only when the ignition checker is used.
NOTE:Remove the following parts before inspection.
1) Seat
2) Fuel tank
Use the following special tools in this inspection.
*1 Check fuse.Replace fuse and check
wire harness.
*2 Check battery. Recharge or replace.
Spark gap test*3 Clean or replace spark
plug.
Check entire ignition system for
connection.
(couplers, leads and ignition coil)Repair or replace.
Check engine stop switch. Replace.
Check main switch.Replace.
Check ignition coil. Primary coil Replace.
Secondary coil Replace.
Check AC magneto. Pickup coil Replace.
Check neutral switch. Repair or replace.
Replace CDI unit.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754
Pocket tester:
YU-3112-C/
90890-03112
No good
OK
No good
OK
Spark
No spark
No good
OK
No good
OK
No good
OK
No good
OKNo good
No good
OK
No good
OK

6 - 13
–+ELECIGNITION SYSTEM
SPARK GAP TEST
1. Disconnect the ignition coil from
spark plug.
2. Remove the ignition coil cap.
3. Connect the dynamic spark
tester
1 (ignition checker
2) as
shown.
Ignition coil
3
Spark plug
4
ÈFor USA and CDN
ÉExcept for USA and CDN
4. Kick the kickstarter crank.
5. Check the ignition spark gap.
6. Start engine, and increase spark
gap until misfire occurs. (for USA
and CDN only)
Minimum spark gap:
6.0 mm (0.24 in)
È
É
COUPLERS, LEADS AND
IGNITION COIL CONNECTION
INSPECTION
1. Check:
Couplers and leads connec-
tion
Rust/dust/looseness/short-cir-
cuit
→ Repair or replace.
Ignition coil and spark plug as
they are fitted
Push in the ignition coil until it
closely contacts the spark plug
hole in the cylinder head
cover.
ENGINE STOP SWITCH
INSPECTION
1. Inspect:
Engine stop switch conduct
No continuity while being pushed
→
Replace.
Continuity while being freed
→
Replace.Tester (+) lead →
Black lead 1

Tester (–) lead →
Black lead 2

B
1
B
2
Tester
selector
position
PUSH IN
Ω
×
1
FREE
TEST DE LA LONGUEUR
D’ETINCELLE D’ALLUMAGE
1. Déconnecter la bobine d’allumage
de la bougie.
2. Déposer le capuchon de la bobine
d’allumage.
3. Connecter le testeur dynamique
d’étincelle 1 (testeur d’allumage
2) comme indiqué.
Bobine d’allumage 3
Bougie 4
È
USA et CDN
É
Excepté USA et CDN
4. Actionner le kick.
5. Contrôler la longueur d’étincelle
d’allumage.
6. Démarrer le moteur et augmenter la
longueur d’étincelle jusqu’à ce
qu’un raté se produise. (uniquement
USA et CDN)
Longueur d’étincelle
minimum:
6,0 mm (0,24 in)
CONTROLE DES CONNEXIONS
DES RACCORDS, FILS ET BOBINE
D’ALLUMAGE
1. Contrôler:
Connexion de coupleurs et fils
Rouille/poussière/jeu/court-cir-
cuit → Réparer ou remplacer.
Bobine d’allumage et bougie tel-
les quelles
Insérer la bobine d’allumage
jusqu’à ce qu’elle touche le trou
de bougie dans le couvercle de la
culasse.
CONTROLE DU COUPE-CIRCUIT
DU MOTEUR
1. Contrôler:
Continuité du coupe-circuit du
moteur
Pas de continuité lorsqu’enfoncé →
Remplacer.
Continuité lorsque relâché → Rempla-
cer.Fil (+) de multimètre → Fil noir 1
Fil (–) de multimètre → Fil noir 2
B
1 B
2 Position de
sélecteur du
multimètre
ENFONCE
Ω × 1
RELACHE
SYSTEME D’ALLUMAGE

6 - 21
–+ELECELECTRIC STARTING SYSTEM
ELECTRIC STARTING
SYSTEM
STARTING CIRCUIT CUT-OFF
SYSTEM OPERATION
If the main switch is set to “ON”, the
starter motor can only operate if at
least one of the following conditions
is met:
The transmission is in neutral (the
neutral switch is closed).
The clutch lever is pulled to the
handlebar (the clutch switch is
closed).
The starting circuit cut-off relay pre-
vents the starter motor from operat-
ing when neither of these conditions
has been met. In this instance, the
starting circuit cut-off relay is open so
current cannot reach the starter
motor. When at least one of the
above conditions has been met the
starting circuit cut-off relay is closed
and the engine can be started by
pressing the start switch.
WHEN THE TRANS-
MISSION IS IN NEU-
TRAL
WHEN THE CLUTCH
LEVER IS PULLED
TO THE HANDLEBAR
1Battery
2Main fuse
3Main switch
4Starting circuit cut-off relay
5Start switch
6Diode
7Clutch switch
8Neutral switch
9Starter relay
0Starter motor
12
M
3
4
5
8 76 9
0
SYSTEM DE DEMAR-
RAGE ELECTRIQUE
FONCTIONNEMENT DU
SYSTEME DE COUPURE-CIRCUIT
DE DEMARRAGE
Lorsque le commutateur principal est sur
“ON”, le démarreur ne fonctionne que si
au moins une des deux conditions sui-
vantes est remplie:
La boîte de vitesses est au point mort
(le contacteur de point mort est
fermé).
Le levier d’embrayage est tiré vers le
guidon (le contacteur d’embrayage est
fermé).
Le relais de coupe-circuit de démarrage
empêche le démarreur de fonctionner
lorsque aucune de ces conditions n’est
remplie. Dans ce cas, le relais de coupe-
circuit de démarrage est ouvert, de sorte
que le courant ne peut atteindre le
démarreur. Toutefois, si au moins une
des conditions décrites ci-dessus a été
remplie, le relais de coupe-circuit de
démarrage est fermé et le moteur peut
être mis en marche en appuyant sur le
contacteur du démarreur.
LORSQUE LA BOITE
DE VITESSES EST AU
POINT MORT
LORSQUE LE LEVIER
D’EMBRAYAGE EST
TIRE VERS LE GUI-
DON
1
Batterie
2
Fusible principal
3
Commutateur principal
4
Relais de coupe-circuit de démarrage
5
Contacteur du démarreur
6
Diode
7
Contacteur d’embrayage
8
Contacteur de point mort
9
Relais du démarreur
0
Moteur de démarreur
SYSTEM DE DEMARRAGE ELECTRIQUE