CHAPTER 4
ENGINE
SEAT, FUEL TANK AND SIDE
COVERS..................................... 4-1
EXHAUST PIPE AND
SILENCER.................................. 4-7
RADIATOR............................... 4-13
CARBURETOR........................ 4-21
CAMSHAFTS........................... 4-51
CYLINDER HEAD.................... 4-73
VALVES AND VALVE
SPRINGS.................................. 4-81
CYLINDER AND PISTON...... 4-101
CLUTCH................................. 4-117
OIL FILTER ELEMENT,
WATER PUMP AND RIGHT
CRANKCASE COVER........... 4-135
BALANCER............................ 4-151
OIL PUMP.............................. 4-159
KICK SHAFT AND
SHIFT SHAFT........................ 4-169
AC MAGNETO AND STARTER
CLUTCH................................. 4-185
ENGINE REMOVAL............... 4-207
CRANKCASE AND
CRANKSHAFT....................... 4-221
TRANSMISSION, SHIFT CAM
AND SHIFT FORK................. 4-245
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR
WHEEL....................................... 5-1
FRONT BRAKE AND
REAR BRAKE.......................... 5-23
FRONT FORK.......................... 5-61
HANDLEBAR........................... 5-91
STEERING............................. 5-103
SWINGARM........................... 5-119
REAR SHOCK ABSORBER.. 5-139
CHAPITRE 4
MOTEUR
SELLE, RESERVOIR DE
CARBURANT ET CACHES
LATERAUX..................................... 4-2
TUYAU D’ECHAPPEMENT ET
SILENCIEUX................................... 4-8
RADIATEUR................................. 4-14
CARBURATEUR.......................... 4-22
ARBRES A CAMES...................... 4-52
CULASSE....................................... 4-74
SOUPAPES ET RESSORTS DE
SOUPAPE....................................... 4-82
CYLINDRE ET PISTON............ 4-102
EMBRAYAGE............................. 4-118
ELEMENT DE FILTRE A
HUILE, POMPE A EAU ET
DEMI-CARTER DROIT............ 4-136
BALANCIER............................... 4-152
POMPE A HUILE....................... 4-160
ARBRE DE KICK ET
ARBRE DE SELECTEUR.......... 4-170
MAGNETO CA ET
ROCHET DE DEMARRAGE ... 4-186
DEPOSE DU MOTEUR.............. 4-208
CARTER ET VILEBREQUIN... 4-222
BOITE A VITESSES,
TAMBOUR ET FOURCHETTES
DE SELECTION.......................... 4-246
CHAPITRE 5
PARTIE CYCLE
ROUE AVANT ET ROUE
ARRIERE......................................... 5-2
FREIN AVANT ET FREIN
ARRIERE....................................... 5-24
FOURCHE AVANT...................... 5-62
GUIDON......................................... 5-92
DIRECTION................................ 5-104
BRAS OSCILLANT.................... 5-120
AMORTISSEUR ARRIERE...... 5-140
1 - 12
GEN
INFO
SPECIAL TOOLS
YS-1880-A, 90890-01701 Sheave holder
This tool is used for when loosening or tightening the
flywheel magneto securing nut.
YU-3112-C, 90890-03112 Pocket tester
Use this tool to inspect the coil resistance, output
voltage and amperage.
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 - 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
1 - 51
GEN
INFO
EC1B0000
CLEANING AND
STORAGE
EC1B1000CLEANING
Frequent cleaning of your machine
will enhance its appearance, main-
tain good overall 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 enter-
ing. 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 contami-
nation of wheel bearings, front
forks, brakes and transmission
seals. Many expensive repair bills
have resulted from improper high
pressure detergent applications
such as those available in coin-
operated car washers.
4. After the majority of the dirt has
been hosed off, wash all sur-
faces with warm water and a
mild detergent. Use an old tooth-
brush to clean hard-to-reach
places.
5. Rinse the machine off immedi-
ately 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 uphol-
stery cleaner to keep the cover
pliable and glossy.
8. Automotive wax may be applied
to all painted or chromed sur-
faces. Avoid combination
cleaner-waxes, as they may con-
tain abrasives.
9. After completing the above, start
the engine and allow it to idle for
several minutes.
NETTOYAGE ET
RANGEMENT
NETTOYAGE
Un nettoyage fréquent de la machine
améliorera son aspect, maintiendra ses
bonnes performances et augmentera la
durée de service de bon nombre de ses
composants.
1. Avant de laver la moto, boucher la
sortie du pot d’échappement pour
éviter toute pénétration d’eau. Un
sachet en plastique retenu par un
élastique fera l’affaire.
2. Si le moteur est fortement encrassé,
appliquer un peu de dégraissant au
pinceau. Eviter tout contact avec la
chaîne, ses pignons et les axes de
roue.
3. Rincer la boue et le dégraissant au
tuyau d’arrosage, en utilisant juste
la pression suffisante.
ATTENTION:
Une pression excessive risque de pro-
voquer des infiltrations d’eau dans les
roulements des roues, la fourche
avant, des freins et les joints de la
transmission. Noter que bien des notes
de réparation onéreuses ont résulté de
l’emploi abusif des vaporisateurs de
détergent à haute pression, tels que
ceux qui équipent les laveries automa-
tiques de voitures.
4. Après avoir chassé la majeure partie
de la boue, laver toutes les surfaces
avec de l’eau chaude et un détergent
neutre. Utiliser une vieille brosse à
dents pour atteindre les endroits dif-
ficiles d’accès.
5. Rincer immédiatement l’engin avec
de l’eau propre et sécher toutes les
surfaces avec un chiffon doux.
6. Immédiatement après le lavage, éli-
miner l’excès d’eau de la chaîne
avec des mouchoirs en papier et
lubrifier la chaîne pour éviter
qu’elle ne rouille.
7. Nettoyer la selle avec un produit
pour meubles rembourrés pour que
sa housse reste souple et brillante.
8. Un encaustique pour automobile
peut être appliqué sur toutes les sur-
faces peintes et chromées. Eviter les
liquides de nettoyage à encaustique,
car ils contiennent de l’abrasif.
9. Les opérations ci-dessus terminées,
lancer le moteur et le laisser tourner
pendant quelques minutes.
CLEANING AND STORAGE
NETTOYAGE ET RANGEMENT
1 - 53
GEN
INFO
EC1B2001STORAGE
If your machine is to be stored for 60
days or more, some preventive mea-
sures must be taken to avoid deterio-
ration. After cleaning the machine
thoroughly, prepare it for storage as
follows:
1. Drain the fuel tank, fuel lines,
and the carburetor float bowl.
2. Remove the spark plug, pour a
tablespoon of SAE 10W-30
motor oil in the spark plug hole,
and reinstall the plug. With the
engine stop switch pushed in,
kick the engine over several
times to coat the cylinder walls
with oil.
3. Remove the drive chain, clean it
thoroughly with solvent, and
lubricate it. Reinstall the chain or
store it in a plastic bag tied to the
frame.
4. Lubricate all control cables.
5. Block the frame up to raise the
wheels off the ground.
6. Tie a plastic bag over the
exhaust pipe outlet to prevent
moisture from entering.
7. If the machine is to be stored in a
humid or salt-air environment,
coat all exposed metal surfaces
with a film of light oil. Do not
apply oil to rubber parts or the
seat cover.
NOTE:Make any necessary repairs before
the machine is stored.RANGEMENT
Si l’on remise la machine pour 60 jours
ou plus, il faut prendre des mesures de
conservation pour éviter sa détérioration.
Après un nettoyage soigné, préparer la
machine de la manière suivante:
1. Vider le réservoir, les conduites
d’essence et la cuve du carburateur.
2. Déposer la bougie, verser une
cuillère à soupe d’huile moteur SAE
10W-30 dans le trou de bougie, et la
remettre en place. Coupe-circuit à la
position arrêt, donner plusieurs
coups de kick pour enduire le cylin-
dre d’huile.
3. Déposer la chaîne, la nettoyer soi-
gneusement au dissolvant et lubri-
fier. Remonter la chaîne ou la
ranger dans un sachet plastique
fermé fixé au cadre.
4. Lubrifier tous les câbles de com-
mande.
5. Mettre le cadre sur plots pour soule-
ver les roues du sol.
6. Fixer un sachet plastique sur la sor-
tie du pot d’échappement pour évi-
ter l’introduction d’humidité.
7. Si la machine est placée dans une
atmosphère humide ou marine,
enduire toutes les surfaces métalli-
ques nues d’une fine couche
d’huile. Ne pas appliquer d’huile
sur les parties en caoutchouc ou sur
la selle.
N.B.:
Avant de ranger la machine, effectuer
toutes les réparations nécessaires.
CLEANING AND STORAGE
NETTOYAGE ET RANGEMENT
GENERAL SPECIFICATIONS
2 - 1
SPEC
EC200000
SPECIFICATIONS
EC211000
GENERAL SPECIFICATIONS
Model name: WR250FS (USA)
WR250F (EUROPE)
WR250F(S) (CDN, AUS, NZ, ZA)
Model code number: 5UM5 (USA)
5UM6 (EUROPE)
5UM7 (CDN, AUS, NZ, ZA)
Dimensions:
Overall length 2,165 mm (85.2 in)
Overall width 827 mm (32.6 in)
Overall height 1,303 mm (51.3 in)
Seat height 998 mm (39.3 in)
Wheelbase 1,475 mm (58.1 in)
Minimum ground clearance 382 mm (15.0 in)
Dry weight:
Without oil and fuel 105.5 kg (232.6 lb)
Engine:
Engine type Liquid cooled 4-stroke, DOHC
Cylinder arrangement Single cylinder, forward inclined
Displacement 249 cm
3 (8.76 Imp oz, 8.42 US oz)
Bore × stroke 77.0 × 53.6 mm (3.03 × 2.11 in)
Compression ratio 12.5 : 1
Starting system Kick and electric starter
Lubrication system: Dry sump
Oil type or grade:
Engine oil (For USA and CDN)
At 5 °C (40 °F) or higher È
Yamalube 4 (20W-40) or SAE 20W-40 type
SG motor oil
(Non-Friction modified)
At 15 °C (60 °F) or lower É
Yamalube 4 (10W-30) or SAE 10W-30 type
SG motor oil
(Non-Friction modified)
and/or
Yamalube 4-R (15W-50)
(Non-Friction modified)
(Except for USA and CDN)
API “SG” or higher grade
-20
-4-10
140
3010
5020
6830
8640 50
104
122˚CTemp.
˚F
10W-30
10W-40
20W-40
20W-50
15W-40
2
GENERAL SPECIFICATIONS
2 - 3
SPEC
Brake:
Front brake type Single disc brake
Operation Right hand operation
Rear brake type Single disc brake
Operation Right foot operation
Suspension:
Front suspension Telescopic fork
Rear suspension Swingarm (link type monocross suspension)
Shock absorber:
Front shock absorber Coil spring/oil damper
Rear shock absorber Coil spring/gas, oil damper
Wheel travel:
Front wheel travel 300 mm (11.8 in)
Rear wheel travel 315 mm (12.4 in)
Electrical:
Ignition system CDI
Generator system AC magneto
Battery type YTX5L-BS
Battery voltage/capacity 12 V/4 AH
Specific gravity 1.320
Headlight type: Quartz bulb (halogen)
Bulb wattage × quantity:
Headlight 12 V 60/55 W × 1
Taillight 12 V 21/5 W × 1
MAINTENANCE SPECIFICATIONS
2 - 11
SPEC
NOTE:
- marked portion shall be checked for torque tightening after break-in or before each race. Silencer M8 × 1.25 2 35 3.5 25
Silencer clamp M8 × 1.25 1 16 1.6 11
Spark arrester (for USA) M6 × 1.0 3 10 1.0 7.2
Silencer end pipe (for USA) M6 × 1.0 1 10 1.0 7.2
Crankcase M6 × 1.0 11 12 1.2 8.7
Crankcase bearing stopper M6 × 1.0 11 10 1.0 7.2
Crankcase bearing stopper (crankshaft) M6 × 1.0 4 10 1.0 7.2
Left crankcase cover M6 × 1.0 8 10 1.0 7.2
Idle gear cover (starter motor) M6 × 1.0 3 10 1.0 7.2
Idle gear plate M6 × 1.0 2 10 1.0 7.2
Right crankcase cover M6 × 1.0 8 10 1.0 7.2
Clutch cover M6 × 1.0 7 10 1.0 7.2
Crankcase oil drain bolt M10 × 1.25 1 20 2.0 14
Drive chain sprocket cover M6 × 1.0 2 8 0.8 5.8
Kick shaft ratchet wheel guide M6 × 1.0 2 12 1.2 8.7
Kickstarter crank M8 × 1.25 1 33 3.3 24
Primary drive gear M18 × 1.0 1 75 7.5 54
Clutch spring M6 × 1.0 5 8 0.8 5.8
Clutch boss M16 × 1.0 1 60 6.0 43
Push lever shaft M6 × 1.0 1 10 1.0 7.2
Drive sprocket M18 × 1.0 1 75 7.5 54
Drive axle oil seal stopper M6 × 1.0 2 10 1.0 7.2
Segment M8 × 1.25 1 30 3.0 22
Shift guide M6 × 1.0 2 10 1.0 7.2
Stopper lever M6 × 1.0 1 10 1.0 7.2
Shift pedal M6 × 1.0 1 12 1.2 8.7 Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb