2003 YAMAHA WR 250F fuel

4 - 73
ENGCYLINDER HEAD
CYLINDER HEAD
Extent of removal:
1 Cylinder head removal
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE COVERS”
section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND SILENCER” section.
Radiator hose 1 Disconnect at cylinder head side.
Carburetor Refer to “CARBURETOR” section.
Camshaft Refer to “CAMSHAFTS” section.
Upper engine bracket Refer to “ENGINE REMOVAL” section.
1 Radiator pipe 1
2 Oil delivery pipe 1
3Nut 2
4 Bolt [L=135 mm (5.31 in)] 2
5 Bolt [L=145 mm (5.71 in)] 2
6 Cylinder head 1
7 Timing chain guide (exhaust side) 1
1

4 - 185
ENGAC MAGNETO AND STARTER CLUTCH
AC MAGNETO AND STARTER CLUTCH
Extent of removal:
1 Starter clutch/wheel gear removal
2 Rotor removal
3 Pickup coil/stator removal
Extent of removal Order Part name Q’ty Remarks
AC MAGNETO AND STATOR REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT” section in
the CHAPTER 3.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE COVERS”
section.
Bolt [radiator (left)] Refer to “RADIATOR” section.
Disconnect the AC magneto lead.
1 Shift pedal 1
2 Engine guard (left) 1
3 Cover (idle gear 1) 1
4 Idle gear 1 1
5 Bearing 1
6Shaft 1
7 Crankcase cover (left) 1
8 Gasket 1
9 Dowel pin 2
31

4 - 203
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.
WARNING
Support the machine securely so there is nodanger of it falling over.
Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT” section in
the CHAPTER 3.
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 the engine side.
Radiator Refer to “RADIATOR” section.
Shift pedal Refer to “AC MAGNETO AND STARTER CLUTCH”
section.
Cylinder head breather hose and oil tank
breather hoseRefer to “CAMSHAFTS” section.

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 - 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 - 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 - 45
–+ELECCHARGING SYSTEM
EC680000
CHARGING SYSTEM
EC681001INSPECTION STEPS
If the battery is not charged, use the following inspection steps.
*1 marked: Refer to “FUSE INSPECTION” section in the CHAPTER 3.
*2 marked: Refer to “BATTERY INSPECTION AND CHARGING” section in the CHAPTER 3.
NOTE:Remove the following parts before inspection.
1) Seat
2) Fuel tank
Use the following special tool in this inspection.
*1 Check fuse.Replace fuse and check
wire harness.
*2 Check battery. Recharge or replace.
Check each coupler and wire
connection.Repair or replace.
Check charging voltage. Charging system is good.
Check AC magneto. Charging coil Replace.
Replace rectifier/regulator.
Pocket tester:
YU-3112-C/
90890-03112
Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
No good
OK
No good
OK
No good
OK
OK
No good
No good
OK

6 - 67
–+ELECLIGHTING SYSTEM
LIGHTING SYSTEM
INSPECTION STEPS
Refer to the following flow chart when inspecting the ignition system for possible problems.
NOTE:Replace the bulb and/or bulb socket.
1) Seat
2) Fuel tank
Use the following special tool.
Check the bulb and bulb socket.Replace the bulb and/or
bulb socket.
Check the light switch. Replace.
Check the AC magneto. Lighting coil Replace.
Check the entire lighting system
proper for connections.Repair or replace.
Check the rectifier/regulator. Out-put voltage Replace.
Pocket tester:
YU-3112-C/
90890-03112
Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
No good
OK
No good
OK
No good
OK
Improperly connected
OK
No good