engine YAMAHA YZ450F 2003 Owners Manual

–+ELEC

ZÜNDANLAGE
ZÜNDANLAGE
FEHLERSUCHE
Folgendes Diagramm hilft zündanlagen- und zündkerzenbedingte Motorstörungen zu beheben.
* Nur wenn der Zündfunkenstreckentester verwendet wird
HINWEIS:


Die folgenden Teile vor Beginn der Störungsbeseitigung ausbauen.
1) Sitz
2) Kraftstofftank

Folgendes Spezialwerkzeug verwenden.
Zündfunkenstrecke
kontrollieren*Zündkerze reinigen
oder erneuern.
Kabelanschlüsse der
gesamten Zündenlage
kontrollieren.
(Steckverbinder,
Kabel und Zündspule)Erneuern oder instand
setzen.
Motorstoppschalter
“ENGINE STOP”
kontrollieren.Erneuern.
Zündspule kontrollieren. Primärspule Erneuern.
Sekundär-
spuleErneuern.
CDI-Schwungradmagnet-
zünder kontrollieren.Impulsgeber Erneuern.
Erregerspule Erneuern.
Leerlaufschalter
kontrollieren.Erneuern oder instand
setzen.
CDI-Zündbox erneuern.
Zündfunkenstreckentester
YM-34487
Zündprüfer
90890-06754
Taschen-Multimeter
YU-3112-C/90890-03112
Kein Zündfunke
In Ordnung
In Ordnung
In Ordnung
In Ordnung
Zündfunke
Nicht in Ordnung
In Ordnung
Nicht in Ordnung
Nicht in Ordnung
Nicht in Ordnung
Nicht in Ordnung
Nicht in Ordnung
Nicht in Ordnung

6 - 3

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

–+ELEC
6 - 7
TPS (THROTTLE POSITION SENSOR) SYSTEM
EC690000
TPS (THROTTLE POSITION SENSOR) SYSTEM
INSPECTION STEPS
If the TPS will not operate, use the following inspection steps.
*marked: Refer to “IGNITION SYSTEM” section.
NOTE:
Use the following special tools in this inspection.
Pocket tester:
YU-3112-C/90890-03112Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
Check entire ignition
system for connection.Repair or replace.
Check TPS. TPS coil Replace.
*Check CDI magneto. Source coil Replace.
Check CDI unit.TPS input
voltageReplace.
OK
OK
OK
No good
No good
No good
No good

6 - 8
–+ELECTPS (THROTTLE POSITION SENSOR) SYSTEM
HANDLING NOTE
CAUTION:
Do not loosen the screws {TPS (throttle
position sensor)} 1 except when changing
the TPS (throttle position sensor) due to
failure because it will cause a drop in
engine performance.
1
EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
Couplers and leads connection
Rust/dust/looseness/short-circuit →
Repair or replace.
TPS COIL INSPECTION
1. Inspect:
TPS coil resistance
Out of specification → Replace.
2. Loosen:
Throttle stop screw 1
NOTE:
Turn out the throttle stop screw until the throt-
tle shaft is in the full close position.Tester (+) lead → Blue lead 1
Tester (–) lead → Black lead 2
TPS coil
resistanceTester selector
position
4 ~ 6 kΩ at
20 ˚C (68 ˚F)kΩ × 1

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

7 - 1
TUN

EC700000
TUNING
EC710000
ENGINE
Carburetor setting

The air/fuel mixture will vary depending on
atmospheric conditions. Therefore, it is nec-
essary to take into consideration the air pres-
sure, ambient temperature, humidity, etc.,
when adjusting the carburetor.

Perform a test run to check for proper engine
performance (e.g., throttle response) and
spark plug(-s) discoloration or fouling. Use
these readings to determine the best possi-
ble carburetor setting.
NOTE:

It is recommended to keep a record of all car-
buretor settings and external conditions (e.g.,
atmospheric conditions, track/surface condi-
tions, lap times) to make future carburetor set-
ting easier.
WARNING


The carburetor is a part of the fuel line.
Therefore, be sure to install it in a well-
ventilated area, away from flammable
objects and any sources of fire.

Never look into the carburetor intake.
Flames may shoot out from the pipe if the
engine backfires while it is being started.
Gasoline may be discharged from the
accelerator pump nozzle when the carbu-
retor has been removed.
SETTING

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

7 - 4
TUN

SETTING
Pilot system
The FLATCR carburetor is manufactured with
a pilot screw. The pilot screw adjustment
ranges from fully closed throttle to 1/4 open
throttle.
Main jet adjustment
The richness of the air-fuel mixture at full throt-
tle can be set by changing the main jet
1
.
If the air-fuel mixture is too rich or too lean, the
engine power will drop, resulting in poor accel-
eration.
Effects of changing the main jet (reference)
Å
Idle
ı
Fully open
Standard main jet #165
1/4 1/2 3/4
+10%
#165
–10%
#168
#162
Åı