2001 YAMAHA WR 426F engine

5. GASOLINE IS HIGHLY FLAMMABLE.
Always turn off the engine while refu-
eling. Take care to not spill any gaso-
line on the engine or exhaust system.
Never refuel in the vicinity of an open
flame, or while smoking.
6. GASOLINE CAN CAUSE INJURY.
If you should swallow some gasoline,
inhale excess gasoline vapors, or
allow any gasoline to get into your
eyes, contact a doctor immediately. If
any gasoline spills onto your skin or
clothing, immediately wash skin areas
with soap and water, and change your
clothes.
7. ONLY OPERATE THE MACHINE IN AN
AREA WITH ADEQUATE VENTILA-
TION.
Never start the engine or let it run for
any length of time in an enclosed area.
Exhaust fumes are poisonous. These
fumes contain carbon monoxide,
which by itself is odorless and color-
less. Carbon monoxide is a dangerous
gas which can cause unconscious-
ness or can be lethal.
8. PARK THE MACHINE CAREFULLY;
TURN OFF THE ENGINE.
Always turn off the engine if you are
going to leave the machine. Do not
park the machine on a slope or soft
ground as it may fall over.
9. THE ENGINE EXHAUST PIPE, MUF-
FLER, AND OIL TANK WILL BE VERY
HOT AFTER THE ENGINE HAS BEEN
RUN.
Be careful not to touch them or to
allow any clothing item to contact
them during inspection or repair.
10. PROPERLY SECURE THE MACHINE
BEFORE TRANSPORTING IT.
When transporting the machine in
another vehicle, always be sure it is
properly secured and in an upright
position and that the fuel cock is in
the “OFF” position. Otherwise, fuel
may leak out of the carburetor or fuel
tank.

EC080000
HOW TO USE
THIS MANUAL
EC081000
PARTICULARLY IMPORTANT
INFORMATION
The Safety Alert Symbol means ATTENTION!
BECOME ALERT! YOUR SAFETY IS
INVOLVED!
Failure to follow WARNING instructions could
result in severe injury or death to the machine
operator, a bystander, or a person inspecting
or repairing the machine.
A CAUTION indicates special precautions that
must be taken to avoid damage to the
machine.
NOTE:
A NOTE provides key information to make pro-
cedures easier or clearer.
WARNING
CAUTION:

EC082000
FINDING THE REQUIRED PAGE
1. This manual consists of seven chapters;
“General Information”, “Specifications”,
“Regular inspection and adjustments”,
“Engine”, “Chassis”, “Electrical” and “Tun-
ing”.
2. The table of contents is at the beginning of
the manual. Look over the general layout of
the book before finding then required chap-
ter and item.
Bend the book at its edge, as shown, to
find the required fore edge symbol mark
and go to a page for required item and
description.

ILLUSTRATED SYMBOLS
(Refer to the illustration)
Illustrated symbols
1
to
7
are designed as
thumb tabs to indicate the chapter’s number
and content.
1
General information
2
Specifications
3
Regular inspection and adjustments
4
Engine
5
Chassis
6
Electrical
7
Tuning
Illustrated symbols
8
to
D
are used to identify
the specifications appearing in the text.
8
With engine mounted
9
Special tool
0
Filling fluid
A
Lubricant
B
Tightening
C
Specified value, Service limit
D
Resistance (
W
), Voltage (V), Electric current (A)
Illustrated symbols
E
to
H
in the exploded
diagrams indicate grade of lubricant and loca-
tion of lubrication point.
E
Apply engine oil
F
Apply molybdenum disulfide oil
G
Apply lightweight lithium-soap base grease
H
Apply molybdenum disulfide grease
Illustrated symbols
I
to
J
in the exploded
diagrams indicate where to apply a locking
agent and where to install new parts.
IApply locking agent (LOCTITE®)
JUse new one 12
34
56
78
90
AB
CD
EF
GH
IJ
GEN
INFOSPEC
INSP
ADJ
ENG
CHAS–+ELEC
TUN
T R..
ME
BM
New

EC090010
INDEX
GENERAL INFORMATION
SPECIFICATIONS
REGULAR INSPECTION AND ADJUSTMENTS
ENGINE
CHASSIS
ELECTRICAL
TUNING

CHAPTER 3
REGULAR INSPECTION AND
ADJUSTMENTS
MAINTENANCE INTERVALS
................... 3-1
PRE-OPERATION INSPECTION
AND MAINTENANCE
............................... 3-4
ENGINE
..................................................... 3-5
CHASSIS
................................................. 3-26
ELECTRICAL
.......................................... 3-47
CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS
................................. 4-1
EXHAUST PIPE AND SILENCER
............ 4-2
RADIATOR
................................................ 4-4
CARBURETOR
......................................... 4-8
CAMSHAFTS
.......................................... 4-21
CYLINDER HEAD
................................... 4-28
VALVES AND VALVE SPRINGS
........... 4-32
CYLINDER AND PISTON
....................... 4-41
CLUTCH (WR426F)
................................ 4-48
CLUTCH (WR400F)
................................ 4-55
OIL FILTER, WATER PUMP
AND CRANKCASE COVER (RIGHT)
.... 4-62
BALANCER
............................................ 4-69
OIL PUMP
............................................... 4-72
KICK AXLE AND SHIFT SHAFT
............ 4-76
CDI MAGNETO
....................................... 4-83
ENGINE REMOVAL
................................ 4-87
CRANKCASE AND CRANKSHAFT
....... 4-92
TRANSMISSION, SHIFT CAM
AND SHIFT FORK
................................ 4-101

CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL
...... 5-1
FRONT BRAKE AND REAR BRAKE
..... 5-11
FRONT FORK
......................................... 5-28
HANDLEBAR
.......................................... 5-41
STEERING
.............................................. 5-46
SWINGARM
............................................ 5-52
REAR SHOCK ABSORBER
................... 5-59
CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS AND
WIRING DIAGRAM
................................... 6-1
MAP-CONTROLLED CDI UNIT
................ 6-2
IGNITION SYSTEM
................................... 6-3
TPS (THROTTLE POSITION SENSOR)
SYSTEM
.................................................... 6-7
LIGHTING SYSTEM
................................ 6-11
CHAPTER 7
TUNING
ENGINE
..................................................... 7-1
CHASSIS
................................................. 7-11

1 - 1
GEN
INFO

DESCRIPTION
EC100000
GENERAL INFORMATION
EC110000
DESCRIPTION
1
Clutch lever
2
Decompression lever
3
“ENGINE STOP” button
4
Trip meter
5
Lights switch
6
Front brake lever
7
Throttle grip
8
Radiator cap
9
Fuel tank cap
0
Oil filler plug/dipstick
A
Tail light
B
Kick starter
C
Fuel tank
D
Headlight
E
Radiator
F
Coolant drain bolt
G
Rear brake pedal
H
Valve joint
I
Fuel cock
J
Cold starter knob
K
Hot starter knob (red)
L
Air cleaner
M
Drive chain
N
Shift pedal
O
Front fork
NOTE:

l
The machine you have purchased may differ
slightly from those shown in the following.
l
Designs and specifications are subject to
change without notice.
1
1

GEN
INFO

DESCRIPTION
FAHRZEUGBESCHREIBUNG
DESCRIPCIÓN
ALLGEMEINE
ANGABEN
FAHRZEUGBESCHREI-
BUNG
1
Kupplungshebel
2
Dekompressionshebel
3
Motorstoppschalter “ENGINE
STOP”
4
Tageskilometerzähler
5
Lichtschalter
6
Handbremshebel
7
Gasdrehgriff
8
Kühlerverschlußdeckel
9
Kraftstoffankverschluß
0
Motoröl-Einfüllschraubverschluß/
Tauchstab
A
Rücklicht
B
Kickstarter
C
Kraftstofftank
D
Scheinwerfer
E
Kühler
F
Kühlmittel-Ablaßschraube
G
Fußbremshebel
H
Auslaufschutzventil
I
Kraftstoffhahn
J
Kaltstarterknopf
K
Heißstarterknopf (rot)
L
Luftfilter
M
Antriebskette
N
Schalthebel
O
Teleskopgabel
HINWEIS:

l
Leichte Modell-Abweichungen
möglich.
l
Änderungen an Design und techni-
schen Daten jederzeit vorbehalten.
RENSEIGNEMENTS
GENERAUX
DESCRIPTION
1
Levier d’embrayage
2
Levier de décompression
3
Bouton du coupe-circuit de sécurité
“ENGINE STOP”
4
Compteur de vitesse
5
Interrupteur lumiêres
6
Levier de frein avant
7
Poignée d’accélérateur
8
Bouchon de radiateur
9
Bouchon de réservoir à essence
0
Bouchon d’orifice de remplissage et
jauge d’huile
A
Lampe arrière
B
Démarreur au pied
C
Réservoir de carburant
D
Phare
E
Radiateur
F
Boulon de vidange du liquide de
refroidissement
G
Pédale de frein arrière
H
Joint de robinet
I
Robinet à essence
J
Bouton de démarrage à froid
K
Bouton de démarrage à chaud
(rouge)
L
Filtre à air
M
Chaîne de transmission
N
Pédale de sélecteur
OFourche avant
N.B.:
lVotre machine diffère peut-être par-
tiellement de celles montrées sur ces
photos.
lLa conception et les caractéristiques
peuvent êtres changées sans préavis.
1 - 1
INFORMACIÓN
GENERAL
DESCRIPCIÓN
1Palanca del embrague
2Palanca de descompresión
3Botón de parada del motor “ENGINE
STOP”
4Medidor de trayecto
5Interruptor de las luces
6Palanca del freno delantero
7Empuñadura del acelerador
8Tapa del radiador
9Tapa del depósito de combustible
0Tapón de llenado del aceite/varilla
indicadora del nivel de aceite
APiloto trasero
BArrancador de pedal
CDepósito de combustible
DFaro delantero
ERadiador
FPerno de drenaje del refrigerante
GPedal del freno trasero
HJunta de la válvula
IGrifo de combustible
JPomo de arranque en frío
KPomo de arranque en caliente
(pomo rojo)
LDepurador de aire
MCadena de la caja de cambios
NPedal de cambios
OHorquilla delantera
NOTA:
lEl vehículo que ha adquirido puede
diferir ligeramente de los que se mues-
tran a continuación.
lLos diseños y las especificaciones
están sujetos a modificaciones sin pre-
vio aviso.
1