2000 YAMAHA YZ426F engine

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CHASSWINGARM
EC570000
SWINGARM
Extent of removal:1 Swingarm removal
Extent of removal Order Part name Q’ty Remarks
STEERING REMOVAL
Refer to “FRONT BRAKE AND REAR
BRAKE” section.
Shift the brake pedal backward. Preparation for removal Hold the machine by placing the
suitable stand under the engine.
Brake hose holder
Rear caliper
Bolt (brake pedal)
Drive chain
1 Chain support 1
2 Chain tensioner (lower) 1
3 Bolt (rear shock absorber-relay
arm)1 Hold the swingarm.
4 Bolt (connecting rod) 1
5 Pivot shaft 1
6 Swingarm 1
WARNING
Support the machine securely so there is nodanger of it falling over.
1

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CHASREAR SHOCK ABSORBER
EC580000
REAR SHOCK ABSORBER
Extent of removal:1 Rear shock absorber removal2 Rear shock absorber disassembly
Extent of removal Order Part name Q’ty Remarks
Preparation for removalREAR SHOCK ABSORBER
REMOVAL
Hold the machine by placing the
suitable stand under the engine.
Seat and fitting band Refer to “SAET, FUEL TANK AND SIDE
COVERS” section.
Silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
1 Bolt (reservoir tank) 1
2 Clamp (air cleaner joint) 1Only loosening.
3 Rear frame 1
4 Bolt (rear shock absorber-relay
arm)1 Hold the swingarm.
5 Bolt (rear shock absorber-frame) 1
6 Rear shock absorber 1
7 Locknut 1Only loosening.
8 Adjuster 1Only loosening.
9 Spring guide (lower) 1
WARNING
Support the machine securely so there is nodanger of it falling over.
1
2

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ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC600000
ELECTRICAL
EC610000
ELECTRICAL COMPONENTS AND WIRING DIAGRAM
EC611000
ELECTRICAL COMPONENTS
1
“ENGINE STOP” button
2
TPS (throttle position sensor)
3
Neutral switch
4
CDI magneto
5
Ignition coil
6
Spark plug
7
CDI unit
COLOR CODE
B...................... Black
Br .................... Brown
G ..................... Green
L ...................... Blue
O ..................... Orange
P...................... Pink
R ..................... Red
EC612000
WIRING DIAGRAM
7
15
6
2 3 4
LY
BYL
B/LL
G
P
W
R
Y
B
G
BR PBrWG
RB Br WP
R/W WL/W SbW R/W Sb L/WY
B/LL Sb B OY
LB/L B OSbSb
L/WR/W
WSb
B/L
B/WB/W
B/WB/W
Br
BB
LBBY
O
N
13
4
5 2

Sb .................... Sky blue
W ..................... White
Y ...................... Yellow
B/L ................... Black/Blue
B/W .................. Black/White
L/W .................. Blue/White
R/W .................. Red/White
6

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COMPOSANTS ELECTRIQUES ET SCHEMA DE CABLAGE
ELEKTRISCHE BAUTEILE UND SCHALTPLAN
ELEKTRISCHE ANLAGE
ELEKTRISCHE BAUTEILE UND
SCHALTPLAN
ELEKTRISCHE BAUTEILE
1
Motorstoppschalter “ENGINE STOP”
2
Drosselklappensensor
3
Leerlaufschalter
4
CDI-Schwungradmagnetzünder
5
Zündspule
6
Zündkerze
7
CDI-Zündbox
FARB-KODIERUNG
B ...................... schwarz
Br..................... braun
G ..................... grün
L ...................... blau
O ..................... orange
P ...................... rosa
R...................... rot
Sb .................... hellblau
W ..................... weiß
Y ...................... gelb
B/L ................... schwarz/blau
B/W ................. schwarz/weiß
L/W .................. blau/weiß
R/W ................. rot/weiß
SCHALTPLAN
PARTIE ELECTRIQUE
COMPOSANTS ELECTRIQUES ET
SCHEMA DE CABLAGE
COMPOSANTS ELECTRIQUES
1
Bouton d’arrêt du moteur “ENGINE STOP”
2
TPS (détecteur de position d’acceleration)
3
Contacteur de point mort
4
Magnéto CDI
5
Bobine d’allumage
6
Bougie
7
Bloc CDI
CODE DE COULEUR
B .........................Noir
Br ........................Brun
G .........................Vert
L .........................Bleu
O .........................Orange
P..........................Rose
R .........................Rouge
Sb........................Bleu ciel
W ........................Blanc
Y .........................Jaune
B/L......................Noir/Bleu
B/W ....................Noir/Blanc
L/W ....................Bleu/Blanc
R/W ....................Rouge/Blanc
SCHEMA DE CABLAGE
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MAP-CONTROLLED CDI UNIT
MAP-CONTROLLED CDI UNIT
A map-controlled, CDI ignition system is used in the YZ426F.
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.
CDI unit
Throttle position sensor
Pickup coil AC magneto rotorIgnition coil

n
Function of Component

Component Function
TPS
(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 TPS and pickup coil sensor are analyzed by the
computer in the CDI unit, which then adjusts ignition timing for the
operation requirements.
n
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 determined by adding throttle opening to deter-
mine ignition timing (3-dimensional control).
Revolutions
Ignition timing
Throttle opening

3-D Image Map of Ignition Timing
(different from actual characteristics)

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IGNITION SYSTEM
EC620000
IGNITION SYSTEM
EC621001
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.
*marked: Only when the ignition checker is used.
NOTE:

l
Remove the following parts before inspection.
1) Seat
2) Fuel tank
l
Use the following special tools in this inspection.
Spark gap test*Clean or replace
spark plug.
Check entire ignition
system for connection.Repair or replace.
Check “ENGINE STOP”
button.Replace.
Check ignition coil. Primary coil Replace.
Secondary coilReplace.
Check CDI magneto. Pick-up coil Replace.
Source coil Replace.
Check neutral switch. Repair or replace.
Replace CDI unit.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754
Pocket tester:
YU-03112/90890-03112
No Spark
OK
OK
OK
OK
Spark
No good
No good
No good
No good
No good
No good
No good
OK

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SYSTEME D’ALLUMAGE
SYSTEME D’ALLUMAGE
ETAPES DU CONTROLE
Suivre le procédé suivant pour déterminer si le mauvais fonctionnement du moteur est dû à une panne dans le
circuit d’allumage et pour vérifier l une bougie qui ne produit pas d’étincelle.
Indication *: Seulement quand le contrôleur d’allumage et utilisé.
N.B.:

l
Déposer les pièces suivantes avant de procéder au dépistage des pannes.
1) Selle
2) Réservoir à essence
l
Utiliser les outils spéciaux suivants dans ce dépistage des pannes.
Test de longueur d’étincelle* Nettoyer ou remplacer la
bougie.
Contrôler du système entier
d’allumage pour les connexions.Réparer ou remplacer.
Contrôler le bouton d’arrêt du
moteur “ENGINE STOP”.Changer.
Contrôler la bobine d’allumage. Bobine primaire Changer.
Bobine secon-
daireChanger.
Contrôler la magnéto CDI.Bobine d’excita-
tionChanger.
Bobine de source Changer.
Contrôler le contacteur de point
mort.Réparer ou remplacer.
Changer le bloc CDI.
Testeur d’étincelle dynamique:
YM-34487
Contrôleur d’allumage:
90890-06754
Tester de poche:
YU-03112/90890-03112
Pas d’étincelle
O.K.
Etincelle
Mauvais
Mauvais
Mauvais
Mauvais
Mauvais
Mauvais
Mauvais
O.K.
O.K.
O.K.
O.K.

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

l
Die folgenden Teile vor Beginn der Störungsbeseitigung ausbauen.
1) Sitz
2) Kraftstofftank
l
Folgendes Spezialwerkzeug verwenden.
Zündfunkenstrecke
kontrollieren*Zündkerze reinigen
oder erneuern.
Kabelanschlüsse der
gesamten Zündenlage
kontrollieren.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-03112/90890-03112
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

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