valve YAMAHA WR 450F 2003 Service Manual

4 - 40
ENGVALVES AND VALVE SPRINGS
Combination of cylinder head and valve
lifter
1. Combination:
For this combination, match the paint
color on the cylinder head with that on the
valve lifter according to the chart below.
NOTE:
When you purchase a cylinder head, you can-
not designate its size. Choose the valve lifter
that matches the above chart.Combination
Cylinder head mark
a (color)Valve lifter mark
b (color)
Blue Blue
Yellow Yellow
Purple Black
ab
ASSEMBLY AND INSTALLATION
1. Apply:
Molybdenum disulfide oil
Onto the valve stem and valve stem
seal.
2. Install:
Valves 1
Valve spring seats 2
Valve stem seals 3
Valve springs 4
Valve spring retainers 5
NOTE:
Make sure that each valve is installed in its
original place, also referring to the painted
color as follows.
Intake (middle) a: blue
Intake (right/left) b: gray
Exhaust: not paint
Install the valve springs with the larger pitch
c facing upward.
dSmaller pitch
New

4 - 41
ENGVALVES AND VALVE SPRINGS
3. Install:
Valve cotters
NOTE:
While compressing the valve spring with a
valve spring compressor 1 install the valve
cotters.
4. To secure the valve cotters onto the
valve stem, lightly tap the valve tip with a
piece of wood.
CAUTION:
Hitting the valve tip with excessive force
could damage the valve.
Valve spring compressor:
YM-4019/90890-04019
5. Install:
Adjusting pad 1
Valve lifter 2
NOTE:
Apply the engine oil on the valve lifters.
Apply the molybdenum disulfide oil on the
valve stem end.
Valve lifter must turn smoothly when rotated
with a finger.
Be careful to reinstall valve lifters and pads
in their original place.

5 - 28
CHASFRONT FORK
EC558000
FRONT FORK DISASSEMBLY
Extent of removal:1 Oil seal removal2 Damper rod removal
Extent of removal Order Part name Q’ty Remarks
FRONT FORK DISASSEMBLY
1 Cap bolt 1 Refer to “REMOVAL POINTS”.
2 Fork spring 1 Drain the fork oil.
3 Dust seal 1
Refer to “REMOVAL POINTS”. 4 Stopper ring 1
5 Inner tube 1
6 Outer tube 1
7 Piston metal 1
8 Slide metal 1
9 Plain washer 1
0 Oil seal 1
A Spring guide 1
B Base valve 1 Use special tool.
C Damper rod 1 Refer to “REMOVAL POINTS”.
1
2

5 - 30
CHAS
EC553201
Inner tube
1. Remove:
Dust seal 1
Stopper ring 2
Using slotted-head screwdriver.
ACHTUNG:CAUTION:
Take care not to scratch the inner tube.
2. Remove:
Inner tube 1
Oil seal removal steps:
Push in slowly a the inner tube just before
it bottoms out and then pull it back quickly
b.
Repeat this step until the inner tube can
be pulled out from the outer tube.
EC553311
Damper rod
1. Remove:
Base valve 1
Damper rod 2
NOTE:
Use a damper rod holder 3 to lock the damper
rod.
EC554000
INSPECTION
EC554100
Damper rod
1. Inspect:
Damper rod 1
Bend/damage → Replace damper rod.
ACHTUNG:CAUTION:
The front fork with a built-in piston rod has
a very sophisticated internal construction
and is particularly sensitive to foreign
material.
Use enough care not to allow any foreign
material to come in when the oil is replaced
or when the front fork is disassembled and
reassembled.
Damper rod holder:
YM-1423/90890-01423
FRONT FORK

5 - 31
CHAS

EC554200
Base valve
1. Inspect:

Valve assembly
1

Wear/damage
→
Replace.

O-ring
2

Damage
→
Replace.
EC554400
Fork spring
1. Measure:

Fork spring free length
a

Out of specification
→
Replace.
EC554502
Inner tube
1. Inspect:

Inner tube surface
a

Score marks
→
Repair or replace.
Use #1,000 grit wet sandpaper.
Damaged oil lock piece
→
Replace.

Inner tube bends
Out of specification
→
Replace.
Use the dial gauge
1
.
NOTE:

The bending value is shown by one half of the
dial gauge reading.
WARNING

Do not attempt to straighten a bent inner
tube as this may dangerously weaken the
tube.
EC554600
Outer tube
1. Inspect:

Outer tube
1

Score marks/wear/damage
→
Replace.
Fork spring free length:
Standard Limit
460 mm (18.1 in) 455 mm (17.9 in)
Inner tube bending limit:
0.2 mm (0.008 in)
FRONT FORK

5 - 32
CHAS

EC554700
Cap bolt
1. Inspect:

Cap bolt
1


O-ring
2


Air bleed screw
3

Wear/damage
→
Replace.
FRONT FORK
EC555000
ASSEMBLY AND INSTALLATION
Front fork assembly
1. Wash the all parts in a clean solvent.
2. Install:

Damper rod
1

To inner tube
2
.
ACHTUNG:CAUTION:

To install the damper rod into the inner
tube, hold the inner tube aslant. If the inner
tube is held vertically, the damper rod may
fall into it, damaging the valve inside.
3. Install:

Copper washer
1


O-ring
2


Base valve
3

To inner tube
4
.
4. Tighten:

Base valve
1

NOTE:


Use a damper rod holder
2
to lock the
damper rod
3
.

Apply the LOCTITE
®

on the base valve
thread.
Damper rod holder:
YM-1423/90890-01423
New
T R..55 Nm (5.5 m · kg, 40 ft · lb)

5 - 63
CHAS
EC586000
HANDLING NOTE
WARNING
This shock absorber is provided with a
separate type tank filled with high-pressure
nitrogen gas. To prevent the danger of
explosion, read and understand the follow-
ing information before handling the shock
absorber.
The manufacturer can not be held respon-
sible for property damage or personal
injury that may result from improper han-
dling.
1. Never tamper or attempt to disassem-
ble the cylinder or the tank.
2. Never throw the shock absorber into
an open flame or other high heat. The
shock absorber may explode as a
result of nitrogen gas expansion and/
or damage to the hose.
3. Be careful not to damage any part of
the gas tank. A damaged gas tank will
impair the damping performance or
cause a malfunction.
4. Take care not to scratch the contact
surface of the piston rod with the cylin-
der; or oil could leak out.
5. Never attempt to remove the plug at
the bottom of the nitrogen gas tank. It
is very dangerous to remove the plug.
6. When scrapping the shock absorber,
follow the instructions on disposal.
EC587000
NOTES ON DISPOSAL (YAMAHA DEALERS
ONLY)
Before disposing the shock absorber, be sure
to extract the nitrogen gas from valve 1. Wear
eye protection to prevent eye damage from
escaping gas and/or metal chips.
WARNING
To dispose of a damaged or worn-out
shock absorber, take the unit to your
Yamaha dealer for this disposal procedure.
REAR SHOCK ABSORBER

5 - 63
CHAS

HINWEIS ZUM UMGANG MIT DEM
STOSSDÄMPFER
WARNUNG

Der Stoßdämpfer enthält Stick-
stoff unter hohem Druck. Vor
Arbeiten am Stoßdämpfer die fol-
genden Erläuterungen sorgfältig
durchlesen und die gegebenen
Vorsichtsmaßregeln befolgen.
Der Hersteller übernimmt keinerlei
Haftung für Unfälle, Verletzungen
oder Schäden, die auf unsachge-
mäße Behandlung des Stoßdämp-
fers zurückzuführen sind.
1. Den Stoßdämpfer unter kei-
nen Umständen öffnen oder
manipulieren.
2. Den Stoßdämpfer vor Hitze
und offenen Flammen schüt-
zen. Der hitzebedingte
Druckanstieg kann eine Ex-
plosion des Stoßdämpfers
bewirken.
3. Den Gaszylinder vor Verfor-
mung und Beschädigung
schützen. Ein deformierter
Zylinder vermindert die
Dämpfwirkung.
4. Die Kontaktfläche zwischen
Dämpferrohr und Zylinder
nicht zerkratzen, da sonst Öl
austreten kann.
5. UNTER KEINEN UMSTÄN-
DEN die Schraube an der Un-
terseite des Gaszylinders lö-
sen.
6. Den Stoßdämpfer sachge-
mäß entsorgen.
HINWEIS ZUR ENTSORGUNG
(nur Yamaha-Händler)
Vor der Entsorgung des Stoßdämpfers
muß der Gasdruck in dessen Innerem
über das Ventil
1
vollständig abge-
baut werden. Unbedingt eine Schutz-
brille tragen, um Augenverletzungen
durch ausströmendes Gas oder
umherfliegende Metallspäne zu ver-
meiden.
WARNUNG

Den Stoßdämpfer vom Yamaha-
Händler entsorgen lassen.
AMORTISSEUR ARRIERE
FEDERBEIN
AMORTIGUADOR TRASERO
REMARQUES CONCERNANT LA
MANIPULATION
AVERTISSEMENT

Cet amortisseur est muni d’un réser-
voir type séparé contenant de l’azote
sous haute pression. Il doit être de ce
fait manipulé avec une attention parti-
culière. Afin d’éviter les risques
d’explosion, il convient de lire attenti-
vement les instructions suivantes.
Le fabricant de cet amortisseur ne
peut être tenu pour responsable de
tout accident, dommage matériel ou
corporel résultant d’une manipulation
incorrecte.
1. Ne jamais essayer de démonter
l’ensemble cylindre ou le réser-
voir à gaz.
2. Ne jamais jeter un amortisseur
usagé au feu ou l’exposer à une
chaleur intense. L’amortisseur
pourrait exploser suite à la dila-
tation de l’azote qu’il contient
ou à la détérioration du flexible.
3. Prendre garde à ne pas endom-
mager toute partie du réservoir
à gaz. Un réservoir à gaz
endommagé affectera la capa-
cité d’amortissement ou entraî-
nera un mauvais
fonctionnement.
4. Prendre garde à ne pas rayer la
surface de contact de la tige du
piston avec le cylindre; l’huile
pourrait fuir.
5. Ne jamais essayer d’enlever le
plot situé au bas du réservoir à
azote, Il est très dangereux
d’enlever le plot.
6. Pour la mise au rebut de l’amor-
tisseur, suivre les instructions
concernant cette opération.
REMARQUE CONCERNANT LA
MISE AU REBUT DE L’AMORTIS-
SEUR (TRAVAIL A EFFECTUER
CHEZ UN CONCESSIONNAIRE
YAMAHA)
Avant de mettre l’amortisseur au rebut,
ne pas oublier d’extraire l’azote par la
valve
1
. Ne pas oublier de porter des
lunettes de protection pour se protéger
les yeux contre les copeaux métalliques
et le gaz qui s’échappe.
AVERTISSEMENT

Pour mettre au rebut un amortisseur
endommagé ou usé, demander conseil
à un concessionnaire Yamaha.NOTA DE MANEJO
ADVERTENCIA

Este amortiguador incorpora un depó-
sito independiente que contiene gas
nitrógeno de alta presión. Para evitar
el riesgo de una explosión, lea y asegú-
rese de comprender la siguiente infor-
mación antes de manipular el
amortiguador.
El fabricante no puede hacerse res-
ponsable de los daños a la propiedad o
las lesiones personales derivadas de
una manipulación incorrecta.
1. No golpee ni intente desmontar
el cilindro o el depósito.
2. No tire nunca el amortiguador a
una llama libre ni ninguna otra
fuente de calor excesivo. Podría
explotar el amortiguador como
resultado de la expansión del gas
nitrógeno y dañar el tubo.
3. Tenga especial cuidado en no
dañar ninguna pieza del depó-
sito de gas. Un depósito de gas
dañado puede dar lugar a un
rendimiento deficiente de la
amortiguación.
4. Tenga cuidado de no arañar la
superficie de contacto de la vari-
lla del pistón con el cilindro; o
podrían producirse fugas de
aceite.
5. No intente nunca extraer el
tapón de la parte inferior del
depósito de gas nitrógeno ya que
podría resultar muy peligroso.
6. Cuando retire el amortiguador,
siga las instrucciones de dese-
cho.
NOTAS DE DESECHO (SÓLO
PARA CONCESIONARIOS
YAMAHA)
Antes de desechar el amortiguador, ase-
gúrese de extraer el gas nitrógeno de la
válvula
1
. Utilice protección ocular
para evitar lesiones debido al escape de
gas o la proyección de virutas metálicas.
ADVERTENCIA

A la hora de desechar un amortigua-
dor dañado o desgastado, lleve la uni-
dad a su concesionario Yamaha.

–+ELEC

6 - 2
MAP-CONTROLLED CDI UNIT
MAP-CONTROLLED CDI UNIT
A map-controlled, CDI ignition system is used in the WR450F.
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


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.

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).
3-D Image Map of Ignition Timing
(different from actual characteristics)
Revolutions
Ignition timing
Throttle opening

7 - 3
TUN

SETTING
Effects of the setting parts on the throttle
valve opening
1
Pilot screw/pilot jet
2
Throttle valve cutaway
3
Jet needle
4
Main jet
ÅClosed
ıFully open
1/2 3/4 1/4 1/8
1
2
3
4
Åı
Main system
The FLATCR carburetor has a primary main
jet. This type of main jet is perfect for racing
motorcycles since it supplies an even flow of
fuel, even at full load. Use the main jet and the
jet needle to set the carburetor.

1
Jet needle
2
Pilot air jet
3
Needle jet
4
Main jet
5
Pilot jet
6
Pilot screw