stop start YAMAHA WR 426F 2001 User Guide

3 - 19
INSP
ADJIDLE SPEED ADJUSTMENT/
VALVE CLEARANCE ADJUSTMENT
EC35M021
IDLE SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it
up.
2. Adjust:
lIdle speed
Adjustment steps:
lAdjust the pilot screw.
Refer to “PILOT SCREW ADJUSTMENT”
section.
lTurn the throttle stop screw 1 until the
engine runs at the lowest possible speed.
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:
1,700 ~ 1,900 r/min
VALVE CLEARANCE ADJUSTMENT
NOTE:
lThe valve clearance should be adjusted
when the engine is cool to the touch.
lThe piston must be at Top Dead Center
(T.D.C.) on compression stroke to check or
adjust the valve clearance.
1. Remove:
lSeat
lFuel tank
Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
2. Remove:
lCarburetor
Refer to “CARBURETOR” section in
the CHAPTER 4.
lSpark plug cap
lEngine stay (upper)
lCylinder head cover
Refer to “CAMSHAFTS” section in the
CHAPTER 4.
3. Remove:
lTiming plug 1
lStraight plug 2
lO-ring

4 - 17
ENGCARBURETOR
10. Install:
lStarter jet 1
lPilot jet 2
lSpacer 3
lNeedle jet 4
lMain jet 5
11. Install:
lValve seat
lScrew (valve seat) 1
lNeedle valve 2
lFloat 3
lFloat pin 4
NOTE:
lAfter installing the needle valve to the float,
install them to the carburetor.
lCheck the float for smooth movement.
12. Install:
lPilot screw 1
lSpring 2
lWasher 3
lO-ring 4
* Except for USANote the following installation points:
lTurn in the pilot screw until it is lightly
seated.
lTurn out the pilot screw by the number of
turns recorded before removing.
Pilot screw:
WR426F: 1-5/8 turns out
*7/8 turns out
WR400F: 1-1/2 turns out
(example)
13. Install:
lO-ring
lFloat chamber 1
lScrew (float chamber) 2
lCable holder (throttle stop screw cable)
3
lHose holder (carburetor breather hose)
4
WR426F
õWR400F421 3
44õ

6 - 4
–+ELEC

IGNITION SYSTEM
EC622001
SPARK GAP TEST
1. Disconnect the spark plug cap from spark
plug.
2. Connect the dynamic spark tester
1
(ignition checker
2
) as shown.
l
Spark plug cap
3

l
Spark plug
4


For USA and CDN
õ
Except for USA and CDN
3. Kick the kick starter.
4. Check the ignition spark gap.
5. Start engine, and increase spark gap
until misfire occurs. (for USA and CDN
only)
Minimum spark gap:
6.0 mm (0.24 in)

õ

EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
l
Couplers and leads connection
Rust/dust/looseness/short-circuit
®

Repair or replace.
EC625001
“ENGINE STOP” BUTTON INSPECTION
1. Inspect:
l
“ENGINE STOP” button conduct
No continuity while being pushed
®
Replace.
Continuity while being freed
®
Replace.
Tester (+) lead
®
Black/White lead
1

Tester (–) lead
®
Black lead
2

B/W
1
B
2
Tester selec-
tor position
PUSH IN
W

´
1
FREE

–+ELEC
SYSTEME D’ALLUMAGE
ZÜNDANLAGE
SISTEMA DE ENCENDIDO
ZÜNDFUNKENSTRECKE KON-
TROLLIEREN
1. Den Zündkerzenstecker von
der Zündkerze abziehen.
2. Den Zündfunkenstreckente-
ster 1 (bzw. 2) wie abgebil-
det anschließen.
lZündkerzenstecker 3
lZündkerze 4
Nur USA und CDN
õNicht USA und CDN
3.Den Motor mit dem Kick-
starter durchdrehen
.
4. Die Zündfunkenstrecke kon-
trollieren.
5. Den Motor anlassen und die
Zündfunkenstrecke vergrö-
ßern, bis es zu Fehlzündun-
gen kommt (nur USA und
CDN).
Min. Zündfunkenstrecke
6,0 mm
STECKVERBINDER- UND KABEL-
ANSCHLÜSSE KONTROLLIEREN
1. Kontrollieren:
lSteckverbinder- und Kabel-
anschlüsse
Rost/Staub/Lockerheit/Kurz-
schluß ® Instand setzen
oder erneuern.
MOTORSTOPPSCHALTER “ENGI-
NE STOP” KONTROLLIEREN
1. Kontrollieren:
lMotorstoppschalter
(auf Durchgang)
Kein Durchgang bei gedrücktem
Schalter ® Erneuern.
Durchgang bei freigelassenem
Schalter ® Erneuern. Meßkabel (+) ®
Schwarz/Weiß Kabel 1
Meßkabel (–) ®
Schwarz Kabel 2
B/W
1 B
2 Meßge-
rät-
Einstel-
GE-
DRÜCKT
W ´ 1
FREI
TEST DE L’INTERVALLE D’ETIN-
CELLEMENT D’ALLUMAGE
1. Déconnecter le capuchon de bou-
gie de la bougie.
2. Connecter le testeur dynamique
d’étincelle 1 (testeur d’allu-
mage 2) comme indiqué.
lCapuchon de bougie 3
lBougie 4
Pour les USA et le CDN
õExcepté pour les USA et le CDN
3. Actionner le démarreur au pied.
4. Contrôler la longueur d’étincelle
d’allumage.
5. Démarrer le moteur et augmenter
la longueur d’étincelle jusqu’à ce
qu’un raté se produise. (unique-
ment USA et CDN)
Longueur d’étincelle mini-
mum:
6,0 mm (0,24 in)
CONTROLE DES CONNEXIONS
DE COUPLEURS ET FILS
1. Contrôler:
lConnexion de coupleurs et fils
Rouille/poussière/jeu/court-cir-
cuit ® Réparer ou changer.
CONTROLE DU BOUTON
D’ARRET DU MOTEUR “ENGINE
STOP”
1. Vérifier:
lContinuité du bouton d’arrêt du
moteur “ENGINE STOP”
Pas de continuité lorsque enfoncé ®
Changer.
Continuité lorsque relâché ® Changer. Fil (+) de multimètre ®
Fil noir/blanc 1
Fil (–) de multimètre ® Fil noir 2
B/W
1B
2Position de
sélecteur
du multi-
mètre
EN-
FONCE
W ´ 1
RE-
LACHE
6 - 4
PRUEBA DE LA SEPARACIÓN
ENTRE PUNTAS DE LA BUJÍA
1. Desconecte la tapa de puntas de la
bujía de la bujía misma.
2. Conecte el tester dinámico de la
bujía 1 (comprobador de encen-
dido 2) tal y como se muestra.
lTapa de la bujía 3
lBujía 4
Para USA y CDN
õExcepto USA y CDN
3. Accione el arrancador del pedal.
4. Compruebe la separación entre
puntas de la bujía de encendido.
5. Arranque el motor e incremente
la separación entre puntas de la
bujía hasta que deje de saltar la
chispa (solamente para USA y
CDN).
Separación entre puntas
mínima de la bujía:
6,0 mm (0,24 in)
INSPECCIÓN DE ACOPLADORES
Y CONEXIÓN DE CABLES
1. Comprobar:
lConexión de acopladores y
cables
Oxido/polvo/flojedad/cortocir-
cuito ® Reparar o reemplazar.
INSPECCIÓN DEL BOTÓN DE
PARADA DE MOTOR “ENGINE
STOP”
1. Inspeccionar:
lConducto del botón de parada
de motor “ENGINE STOP”
Sin continuidad mientras se mantiene
pulsado ® Reemplazar.
Con continuidad mientras se suelta ®
Reemplazar.Cable del tester (+) ®
Cable negro/blanco 1
Cable del tester (–) ®
Cable negro 2
B/W
1B
2Posición
del selec-
tor del tes-
ter
PULSAR
(PUSH
IN)
W ´ 1
LIBRE

7 - 2
TUN
CAUTION:

l
The carburetor is extremely sensitive to
foreign matter (dirt, sand, water, etc.).
During installation, do not allow foreign
matter to get into the carburetor.
l
Always handle the carburetor and its
components carefully. Even slight
scratches, bends or damage to carbure-
tor parts may prevent the carburetor from
functioning correctly. Carefully perform
all servicing with the appropriate tools
and without applying excessive force.
l
When the engine is stopped or when
riding at no load, do not open and close
the throttle unnecessarily. Otherwise, too
much fuel may be discharged, starting
may become difficult or the engine may
not run well.
l
After installing the carburetor, check that
the throttle operates correctly and opens
and closes smoothly.
Atmospheric conditions and carburetor
settings
The air density (i.e., concentration of oxygen
in the air) determines the richness or lean-
ness of the air/fuel mixture. Therefore, refer
to the above table for mixture settings.
That is:
l
Higher temperature expands the air with its
resultant reduced density.
l
Higher humidity reduces the amount of oxy-
gen in the air by so much of the water vapor
in the same air.
l
Lower atmospheric pressure (at a high alti-
tude) reduces the density of the air.
Air temp. HumidityAir
pressure
(altitude)Mixture Setting
High High Low (high) Richer Leaner
Low Low High (low) Leaner Richer
SETTING