2005 YAMAHA WR 250F ignition

3 - 49
INSP
ADJ
ENGINE IDLING SPEED
ADJUSTMENT
1. Start the engine and thoroughly
warm it up.
2. Adjust:
Engine idling speed
Adjustment steps:
Adjust the pilot screw.
Refer to “PILOT SCREW
ADJUSTMENT” section.
Turn the throttle stop screw
1
until the specified engine idling
speed.
NOTE:Using a digital engine tachometer
for idle speed adjustment, detect
the engine idling speed by bring-
ing the sensing element
c of the
engine tachometer close to the
ignition coil
2.
To increase idle speed →
Turn the throttle stop screw
1 in a.
To decrease idle speed →
Turn the throttle stop screw
1 out b.
Engine idling speed:
1,900 ~ 2,100 r/min
c2
VALVE CLEARANCE INSPECTION
AND ADJUSTMENT
NOTE:The valve clearance should be
adjusted when the engine is cool to
the touch.
The piston must be at Top Dead
Center (T.D.C.) on compression
stroke to check or adjust the valve
clearance.
1. Remove:
Seat
Fuel tank
Refer to “SEAT, FUEL TANK
AND SIDE COVERS” section
in the CHAPTER 4.
2. Drain:
Coolant
Refer to “COOLANT
REPLACEMENT” section.REGLAGE DU REGIME DE
RALENTI DU MOTEUR
1. Mettre le moteur en marche et bien
le laisser chauffer.
2. Régler:
Régime de ralenti
Étapes du réglage:
Régler la vis de ralenti.
Se reporter à la section
“REGLAGE DE LA VIS DE
RALENTI”.
Tourner la vis de butée de papillon
des gaz 1 jusqu’à obtention de la
vitesse de ralenti spécifiée.
N.B.:
A l’aide d’un compte-tours moteur
numérique pour réglage du ralenti,
déterminer le régime de ralenti en
approchant le capteur c du compte-
tours de la bobine d’allumage 2.
Pour augmenter le régime de
ralenti → Serrer la vis de butée
de papillon des gaz 1 dans le
sens a.
Pour diminuer le régime de ralenti
→ Tourner la vis de butée de
papillon des gaz 1 dans le sens
b.
Régime de ralenti:
1.900 à 2.100 tr/min
INSPECTION ET REGLAGE DU
JEU AUX SOUPAPES
N.B.:
Le jeu aux soupapes doit être réglé
quand le moteur est froid au toucher.
Le piston doit être au point mort haut
(PMH) de la course de compression
pour permettre le contrôle ou le
réglage du jeux aux soupapes.
1. Déposer:
Selle
Réservoir de carburant
Se reporter à la section “SELLE,
RESERVOIR DE CARBURANT
ET CACHES LATERAUX” au
CHAPITRE 4.
2. Vidanger:
Liquide de refroidissement
Se reporter à la section “CHAN-
GEMENT DU LIQUIDE DE
REFROIDISSEMENT”.
ENGINE
MOTEUR

3 - 107
INSP
ADJ
EC370000
ELECTRICAL
EC371001SPARK PLUG INSPECTION
1. Remove:
Spark plug
2. Inspect:
Electrode
1
Wear/damage
→ Replace.
Insulator color
2
Normal condition is a medium
to light tan color.
Distinctly different color
→
Check the engine condition.
NOTE:When the engine runs for many
hours at low speeds, the spark plug
insulator will become sooty, even if
the engine and carburetor are in
good operating condition.
3. Measure:
Plug gap
a
Use a wire gauge or thickness
gauge.
Out of specification
→ Regap.
4. Clean the plug with a spark plug
cleaner if necessary.
Spark plug gap:
0.7 ~ 0.8 mm
(0.028 ~ 0.031 in)
5. Tighten:
Spark plug
NOTE:Before installing a spark plug,
clean the gasket surface and plug
surface.
Finger-tighten
a the spark plug
before torquing to specification
b.
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)
IGNITION TIMING CHECK
1. Remove:
Timing mark accessing screw
1
PARTIE ELECTRIQUE
CONTROLE DE LA BOUGIE
1. Déposer:
Bougie
2. Contrôler:
Electrode 1
Usure/endommagement → Rem-
placer.
Couleur de l’isolant 2
La couleur normale est une cou-
leur bronze clair ou légèrement
foncé.
Couleur franchement différente
→ Contrôler l’état du moteur.
N.B.:
Lorsque le moteur tourne pendant des
heures à bas régime, l’isolant de la bou-
gie s’encrasse, même si le moteur et le
carburateur sont en bon état de fonction-
nement.
3. Mesurer:
Ecartement a
Utiliser un calibre pour fils ou un
calibre d’épaisseur.
Hors spécifications → Régler.
4. Si nécessaire, nettoyer la bougie à
l’aide d’un nettoie-bougies.
Ecartement des électrodes:
0,7 à 0,8 mm
(0,028 à 0,031 in)
5. Serrer:
Bougie
N.B.:
Avant de monter une bougie, nettoyer
la surface du joint et la surface de la
bougie.
Serrer la bougie à la main a avant de
la serrer au couple correct b.
T R..13 Nm (1,3 m · kg, 9,4 ft · lb)
CONTROLE DE L’AVANCE A
L’ALLUMAGE
1. Déposer:
Vis d’accès de repère d’allumage
1
ELECTRICAL
PARTIE ELECTRIQUE

3 - 109
INSP
ADJ
2. Attach:
Timing light
Inductive tachometer
To the ignition coil lead
(orange lead
1).
Timing light:
YM-33277-A/
90890-03141
1
3. Adjust:
Engine idling speed
Refer to “ENGINE IDLING
SPEED ADJUSTMENT” sec-
tion.
4. Check:
Ignition timing
Visually check the stationary
pointer
a is within the firing
range b on the rotor.
Incorrect firing range → Check
rotor and pickup assembly.
5. Install:
Timing mark accessing screw
2. Fixer:
Lampe stroboscopique
Compte-tours inductif
Au fil de la bobine d’allumage
(fil orange 1).
Lampe stroboscopique:
YM-33277-A/
90890-03141
3. Régler:
Régime de ralenti du moteur
Se reporter à la section
“REGLAGE DU REGIME DE
RALENTI DU MOTEUR”.
4. Contrôler:
Avance à l’allumage
Contrôler visuellement que
l’index fixe a se trouve dans la
plage d’allumage b indiquée sur
le rotor.
Plage d’allumage incorrecte →
Contrôler le rotor et le capteur
d’allumage.
5. Monter:
Vis d’accès de repère d’allumage
ELECTRICAL
PARTIE ELECTRIQUE

3 - 129
INSP
ADJ
2. Check:
Continuity
2Reserve fuse
Checking steps:
Remove the fuse
1.
Connect the pocket tester to the
fuse and check the continuity.
NOTE:Set the pocket tester selector to
“
Ω
× 1”.
Pocket tester:
YU-3112-C/
90890-03112
If the pocket tester indicates
“
∞”, replace the fuse.
2
1
3. Replace:
Blown fuse
WARNING
Never use a fuse with an amper-
age rating other than that speci-
fied. Improvising or using a fuse
with the wrong amperage rating
may cause extensive damage to
the electrical system, cause the
starting and ignition systems to
malfunction and could possibly
cause a fire.
4. Install:
Fuse cover
Seat Replacement steps:
Set the main switch to “OFF”.
Install a new fuse of the correct
amperage.
Set on the switches to verify if
the electrical circuit is opera-
tional.
If the fuse immediately blows
again, check the electrical cir-
cuit.
ItemsAmperage
ratingQ’ty
Main fuse 10 A 1
2. Contrôler:
Continuité
2
Fusible de réserve
Etapes du contrôle:
Déposer le fusible 1
.
Connecter le multimètre au fusible
et contrôler la continuité du circuit.
N.B.:
Régler le sélecteur du multimètre sur
“Ω × 1”.
Multimètre:
YU-3112-C/90890-03112
Si le multimètre indique “∞”, rem-
placer le fusible.
3. Remplacer:
Fusible grillé
AVERTISSEMENT
Ne jamais utiliser un fusible d’ampé-
rage différent de celui spécifié. Toute
improvisation ou la mise en place d’un
fusible d’un ampérage incorrect ris-
que de gravement endommager le cir-
cuit électrique, de provoquer un
mauvais fonctionnement des systèmes
de démarrage et d’allumage, voire de
provoquer un incendie.
4. Monter:
Couvercle de la boîte à fusibles
Selle Etapes de remplacement:
Placer le contacteur à clé sur
“OFF”.
Monter un nouveau fusible
d’ampérage correct.
Mettre les contacteurs en circuit
pour s’assurer que le circuit électri-
que fonctionne.
Si le fusible grille de nouveau, con-
trôler le circuit électrique.
Eléments Ampérage Qté
Fusible
principal10 A 1
ELECTRICAL
PARTIE ELECTRIQUE

4 - 211
ENGENGINE REMOVAL
Extent of removal:
1 Engine removal
Extent of removal Order Part name Q’ty Remarks
Ignition coil
Disconnect the AC magneto lead.
Starter motor lead Disconnect at the starter motor side.
Negative battery lead Disconnect at the engine side.
Right engine guard
1 Neutral switch 1
2 Drive chain sprocket cover 1
3 Nut (drive sprocket) 1
Refer to “REMOVAL POINTS”. 4 Lock washer 1
5 Drive sprocket 1
6 Clip 1
7 Bolt (brake pedal) 1
8 Brake pedal 1
9 Upper engine bracket 2
10 Lower engine bracket 2
11 Engine mounting bolt 3
12 Pivot shaft 1
Refer to “REMOVAL POINTS”.
13 Engine 1
1

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
HMain switch
ICDI unit
JBatteryCOLOR 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
WR
WR
R
BR/BBr
R
BR/BBr
RW
L/RL/BBB
SbL/W
L/YBBB
WY
RYW
R
LY
B
YLB/L
B
B
ON
OFF
10A
BB
OFF
STARTSTART
R-BrL/W
B
BrL/W
BrL/W
L/B-YB
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
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
CD
BH
5
9
G3 4
A 2I
EF
6 78
1
0J
WY
YW

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.
Throttle position sensorCDI unitIgnition coil
Pickup coilAC magneto rotor
Ignition timing
Th
rot
t
le
o
peni
ngRev
ol
ut
ion
s

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