2002 YAMAHA YZ426F lock

5 - 29
CHASFRONT FORK
EC556000
HANDLING NOTE
NOTE:
The front fork requires careful attention. So it is
recommended that the front fork be main-
tained at the dealers.
ACHTUNG:CAUTION:
To prevent an accidental explosion of air,
the following instructions should be
observed:
The front fork with a built-in piston rod
has a very sophisticated internal con-
struction 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 disas-
sembled and reassembled.
Before removing the cap bolts or front
forks, be sure to extract the air from the
air chamber completely.
EC553000
REMOVAL POINTS
EC553150
Cap bolt
1. Remove:
Cap bolt 1
From the outer tube.
NOTE:
Before removing the front fork from the
machine, loosen the cap bolt.
2. Remove:
Cap bolt 1
NOTE:
While compressing the fork spring, set the
thin type spanners 2 between the spacer 3
and spring guide 4.
Hold the locknut 5 and remove the cap bolt.

5 - 29
CHAS
FOURCHE AVANT
TELESKOPGABEL
HANDHABUNGSHINWEIS
HINWEIS:
Die Teleskopgabel erfordert besondere Auf-
merksamkeit und sollte am besten vom
Yamaha-Händler gewartet werden.
ACHTUNG:
Um einen plötzlichen Druckverlust und da-
mit verbundene Gefahren zu vermeiden,
unbedingt folgende Hinweise beachten.
Der feine Teleskopgabel-Mechanismus ist
sehr auf Fremdstoffe anfällig.
Deshalb beim Gabelölwechsel sowie bei
der Demontage und -Montage darauf ach-
ten, daß keine Fremdstoffe in die Tele-
skopgabel eindringen.
Vor dem Lösen der Verschlußschrauben
unbedingt die Luft aus den Gabelbeinen
vollständig ablassen.
AUSBAU
Verschlußschraube
1. Demontieren:
Verschlußschraube 1
(vom Standrohr)
HINWEIS:
Die Verschlußschrauben vor der Teleskopga-
bel-Demontage lockern.
2. Demontieren:
Verschlußschraube 1
HINWEIS:
Die Gabelfeder komprimieren und dabei ei-
nen flachen Schlüssel 2 zwischen dem Di-
stanzstück 3 und dem Federsitz 4 anset-
zen.
Die Sicherungsmutter 5 gegenhalten und die
Verschlußschraube lösen. REMARQUES CONCERNANT LA
MANIPULATION
N.B.:
La fourche avant nécessite une soigneuse attention.
Il est donc recommandé de la faire entretenir chez
le revendeur.
ATTENTION:
Pour éviter une explosion accidentelle, les ins-
tructions suivantes doivent être observées:
La construction interne d’une fourche avant à
tige de piston incorporée est très sophistiquée
et est particulièrement sensible aux substances
étrangères.
Faire suffisamment attention à ne pas laisser
pénétrer de substances étrangères lorsque
l’huile est remplacée ou lorsque la fourche
avant est démontée ou remontée.
Avant de dévisser les boulons capuchons ou
d’enlever la fourche avant, être sûr d’avoir
complètement extrait l’air du réservoir d’air.
POINTS DE DEPOSE
Boulon capuchon
1. Déposer:
Boulon capuchon 1
Du tube externe.
N.B.:
Avant de démonter la fourche avant de la machine,
desserrer le boulon capuchon.
2. Déposer:
Boulon capuchon 1
N.B.:
Tout en comprimant le ressort de fourche, placer
la clé à ergots fine 2 entre l’entretoise 3 et le
guide de ressort 4.
Maintenir le contre-écrou 5 et retirer le boulon
capuchon.

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 - 33
CHAS

FRONT FORK
5. Install:

Spring guide
1


Locknut
2

To damper rod
3
.
NOTE:


Install the spring guide with its cut
a
facing
upward.

With its thread
b
facing upward, fully finger
tighten the locknut onto the damper rod.
6. Install:

Dust seal 1
Stopper ring 2
Oil seal 3
Plain washer 4
Slide metal 5
To inner tube 6.
NOTE:
Apply the fork oil on the inner tube.
When installing the oil seal, use vinyl seat a
with fork oil applied to protect the oil seal lip.
Install the oil seal with its manufacture’s
marks or number facing the axle holder side.
New
New
7. Install:
Piston metal 1
NOTE:
Install the piston metal onto the slot on inner
tube.
New
8. Install:
Outer tube 1
To inner tube 2.

5 - 37
CHASFRONT FORK
21. Measure:
Distance a
Out of specification → Turn into the
locknut.
Distance a:
20 mm (0.79 in) or more
Between damper rod 1 top and
locknut 2 top.
22. Loosen:
Rebound damping adjuster 1
NOTE:
Loosen the rebound damping adjuster finger
tight.
Record the set position of the adjuster (the
amount of turning out the fully turned in posi-
tion).
23. Install
Cushion rubber 1
Washer 2
Spacer 3
To cap bolt 4.
NOTE:
Install the cushion rubber with its smaller
dia.end a facing the cap bolt.
24. Install:
Push rod 1
Fork spring 2
NOTE:
Install the fork spring with the damper rod 3
pulled up.
After installing the fork spring, hold the
damper rod end so that it will not go down.
25. Install:
Cap bolt 1
Fully tighten the cap bolt onto the
damper rod by hand.

5 - 38
CHASFRONT FORK
26. Tighten:
Cap bolt (locknut) 1
NOTE:
While compressing the fork spring, set the
thin type spanners 2 between the spacer 3
and spring guide 4.
Hold the locknut 5 and tighten the cap bolt
with specified torque.
27. Install:
Cap bolt 1
To outer tube.
NOTE:
Temporarily tighten the cap bolt.
T R..29 Nm (2.9 m · kg, 21 ft · lb)
28. Install:
Protector guide 1
Installation
1. Install:
Front fork 1
NOTE:
Temporarily tighten the pinch bolts (under
bracket).
Do not tighten the pinch bolts (handle crown)
yet.
2. Tighten:
Cap bolt 1
3. Adjust:
Front fork top end a
Front fork top end (standard) a:
Zero mm (Zero in)
T R..30 Nm (3.0 m · kg, 22 ft · lb)