2003 YAMAHA YZ450F stop start

6 - 4
–+ELEC

IGNITION 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

Å
For USA and CDN
ı
Except for USA and CDN
4. Kick the kick starter.
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)
Å
ı

COUPLERS, LEADS AND IGNITION COIL
CONNECTION INSPECTION
1. Check:

Couplers and leads connection
Rust/dust/looseness/short-circuit
→

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 cyl-
inder head cover.
EC625001
“ENGINE STOP” BUTTON INSPECTION
1. Inspect:

“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
Ω

×
1
FREE
B/W B
11 2 2

–+ELEC

SYSTEME D’ALLUMAGE
ZÜNDANLAGE
ZÜNDFUNKENSTRECKE KONTROLLIEREN
1. Die Zündspule von der Zündkerze ab-
trennen.
2. Die Zündspule ausbauen.
3. Den Zündfunkenstreckentester
1
(bzw.
2
) wie abgebildet anschließen.

Zündkerzenstecker
3


Zündspule
4

Å
Nur USA und CAN
ı
Nicht USA und CAN
4. Den Motor mit dem Kickstarter durchdre-
hen.
5. Die Zündfunkenstrecke kontrollieren.
6. Den Motor anlassen und die Zündfunken-
strecke vergrößern, bis es zu Fehlzün-
dungen kommt (nur USA und CAN).
STECKVERBINDER-, KABEL- UND
ZÜNDSPULENANSCHLÜSSE KONTROL-
LIEREN
1. Kontrollieren:

Steckverbinder- und Kabelanschlüsse
Rost/Staub/Lockerheit/Kurzschluß
→

Instand setzen oder erneuern.

Zündspule und Zündkerze wie ange-
bracht
Die Zündspule eindrücken, bis sie das
Zündkerzenloch im Zylinderkopfdeckel
fest berührt.
MOTORSTOPPSCHALTER “ENGINE STOP”
KONTROLLIEREN
1. Kontrollieren:

Motorstoppschalter
(auf Durchgang)
Kein Durchgang bei gedrücktem Schalter
→
Erneuern.
Durchgang bei freigelassenem Schalter
→
Erneuern.
Min. Zündfunkenstrecke
6,0 mm
Meßkabel (+)
→
schwarz/weiß
1

Meßkabel (–)
→
schwarz
2

B/W
1
B2 Meßgerät-
Einstellung
GE-
DRÜCKT
Ω × 1
FREI
TEST DE L’INTERVALLE
D’ETINCELLEMENT D’ALLUMAGE
1. Débrancher la bobine d’allumage de la bou-
gie.
2. Déposer la bobine d’allumage.
3. Connecter le testeur dynamique d’étincelle 1
(testeur d’allumage 2) comme indiqué.
Bobine d’allumage 3
Bougie 4
ÅPour les E.-U. et le Canada
ıExcepté pour les E.-U. et le Canada
4. Actionner le démarreur au pied.
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 E.-U. et Canada)
INSPECTION DES CONNEXIONS DES
RACCORDS, FILS ET BOBINE
D’ALLUMAGE
1. Contrôler:
Connexion de coupleurs et fils
Rouille/poussière/jeu/court-circuit →
Réparer ou changer.
Mise en place de la bobine d’allumage et de
la bougie
Enfoncer la bobine d’allumage jusqu'à ce
qu’elle touche bien l’orifice de la bougie
dans le couvercle de culasse.
CONTROLE DU BOUTON D’ARRET DU
MOTEUR “ENGINE STOP”
1. Vérifier:
Continuité du bouton d’arrêt du moteur
“ENGINE STOP”
Pas de continuité lorsqu’enfoncé → Changer.
Continuité lorsque relâché → Changer.
Longueur d’étincelle minimum:
6,0 mm (0,24 in)
Fil (+) de testeur → Fil noir/blanc 1
Fil (–) de testeur → Fil noir 2
B/W
1 B
2 Position de
sélecteur de
testeur
EN-
FONCE
Ω × 1
RE-
LACHE
6 - 4

6 - 10
–+ELECTPS (THROTTLE POSITION SENSOR) SYSTEM
4. Adjust:
Idle speed
5. Insert the thin electric conductors 2
(lead) into the TPS coupler 1, as shown,
and connect the tester to them.
CAUTION:
Do not insert the electric conductors
more than required because it may
reduce the waterproof function of the
coupler.
Make sure that a short-circuit does not
develop between the terminals because it
may cause damage to electrical compo-
nents.
6. Start the engine.
7. Adjust:
TPS output voltage Adjustment steps:
Attach the inductive tachometer (engine
tachometer) to the high tension cord.
Turn the throttle stop screw 1 until the
specified idle speed.
Refer to “IDLE SPEED ADJUSTMENT”
section in the CHAPTER 3.
Idle speed:
1,900 ~ 2,100 r/min
Tester (+) lead → Yellow lead 3
Tester (–) lead → Black lead 4
Adjustment steps:
Adjust the installation angle of the TPS 1
to obtain the specified output voltage.
NOTE:
Measure the output voltage accurately with a
digital electronic voltmeter that gives an easy
reading of a small voltage.
TPS output
voltageTester selector
position
0.58 ~ 0.78 V DCV

6 - 11
–+ELECTPS (THROTTLE POSITION SENSOR) SYSTEM
8. Tighten:
Screw (TPS) 1
9. Stop the engine.
1
EC694000
TPS INPUT VOLTAGE INSPECTION
1. Disconnect the TPS coupler.
2. Start the engine.
3. Inspect:
TPS input voltage
Out of specification → Replace the CDI
unit.
Tester (+) lead → Blue lead 1
Tester (–) lead → Black/Blue lead 2
TPS input
voltageTester selector
position
4 ~ 6 V DCV-20

–+ELEC
8. Festziehen:
Schraube (TPS) 1
9. Den Motor stoppen.
PRÜFEN DER TPS-EINGANGSSPANNUNG
1. Die TPS-Steckverbindung trennen.
2. Den Motor starten.
3. Prüfen:
TPS-Eingangsspannung
Außerhalb des Sollwerts → Die CDI-
Einheit austauschen.
Prüfgerätkabel (+) → Blaues Kabel 1
Prüfgerätkabel (–) →
Schwarzes/blaues Kabel 2
TPS-Eingangs-
spannung Prüfgerätein-
stellung
4–6 V DCV-20
8. Serrer:
Vis (TPS) 1
9. Arrêter le moteur.
CONTROLE DE LA TENSION D’ENTREE
DU TPS
1. Débrancher le coupleur de TPS.
2. Démarrer le moteur.
3. Contrôler:
Tension d’entrée du TPS
Hors spécifications → Remplacer le bloc
CDI.
Fil de l’appareil de contrôle (+) → Fil bleu 1
Fil de l’appareil de contrôle (–) →
Fil noir/bleu 2
Tension d’entrée
du TPS Position du sélec-
teur de l’appareil
de contrôle
4 à 6 V DCV-20
6 - 11
SYSTEME TPS (CAPTEUR DU PAPILLON D’ACCELERATION)
TPS-SYSTEM (DROSSELKLAPPEN-POSITIONSSENSOR)

7 - 2
TUN
CAUTION:


The carburetor is extremely sensitive to
foreign matter (dirt, sand, water, etc.).
During installation, do not allow foreign
matter to get into the carburetor.

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.

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.

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:

Higher temperature expands the air with its
resultant reduced density.

Higher humidity reduces the amount of oxy-
gen in the air by so much of the water vapor
in the same air.

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