2003 YAMAHA YZ250F lock

5 - 29
CHASFRONT FORK
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

5 - 30
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:
460 mm (18.1 in)
: 455 mm (17.9 in)
Inner tube bending limit:
0.2 mm (0.008 in)
FRONT FORK

5 - 31
CHAS
Front fork cap bolt
1. Inspect:
Front fork cap bolt 1
O-ring 2
Air bleed screw 3
Wear/damage → Replace.
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
T R..55 Nm (5.5 m · kg, 40 ft · lb)
FRONT FORK

5 - 32
CHAS
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
Oil seal 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.
7. Install:
Piston metal 1
NOTE:
Install the piston metal onto the slot on inner
tube.
8. Install:
Outer tube 1
To inner tube 2.
FRONT FORK

5 - 36
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 front fork cap bolt 4.
NOTE:
Install the cushion rubber with its smaller
dia.end a facing the front fork 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:
Front fork cap bolt 1
Fully tighten the front fork cap bolt onto
the damper rod by hand.

5 - 37
CHASFRONT FORK
26. Tighten:
Front fork 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 front fork
cap bolt with specified torque.
27. Install:
Front fork 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 (lower
bracket).
Do not tighten the pinch bolts (upper bracket)
yet.
2. Tighten:
Front fork cap bolt 1
3. Adjust:
Front fork top end a
Front fork top end (standard) a:
5 mm (0.20 in)
T R..30 Nm (3.0 m · kg, 22 ft · lb)

5 - 45
CHAS
LENKKOPF
Demontage-Arbeiten:1 Untere Gabelbrücke demontieren2 Lager demontieren
ANZUGSREIHENFOLGE:
Lenkerringmutter mit 38 Nm (3,8 m • kg) festziehen.Um eine Umdrehung lockern.Nochmals mit 7 Nm (0,7 m • kg) festziehen.
Demontage-ArbeitenReihen-
folgeBauteil Anz. Bemerkungen
LENKKOPF DEMONTIEREN
WARNUNG
Das Motorrad gegen Umfallen sichern.Vorbereitung für den Ausbau Das Motorrad am Motor aufbocken
Nummernschild
Lenker
Kabelführung
Vorderrad-AbdeckungSiehe unter “LENKER”.
1 Lenkkopfmutter 1
2 Teleskopgabel 2 Siehe unter “TELESKOPGABEL”.
3 Obere Gabelbrücke 1
4 Lenkerringmutter 1 Spezialwerkzeug verwenden.
Siehe unter “AUSBAU”.
5 Untere Gabelbrücke 1
6 Lagerschutzkappe 1
7 Oberes Lager 1
8 Unteres Lager 1 Siehe unter “AUSBAU”.
9 Laufring 2 Siehe unter “AUSBAU”.
1
2
DIRECTION
LENKKOPF
STERZO
DIRECTION
Organisation de la dépose:1 Dépose du té inférieur2 Dépose du roulement
ETAPES DE SERRAGE:
Serrer l’écrou crénelé de direction à un couple d’environ. 38 Nm (3,8 m • kg, 27 ft • lb)Le desserrer d’un tour.Le resserrer à un couple d’environ. 7 Nm (0,7 m • kg, 5,1 ft • lb)
Organisation de la dépose Ordre Nom de pièce QtéRemarques
DEPOSE DE LA DIRECTION
AVERTISSEMENT
Bien soutenir la machine afin qu’elle ne risquepas de se renverser.
Préparation pour la dépose Maintenir la machine en plaçant un support
approprié sous le moteur.
Plaque de numéro
Guidon
Guide de câble
Garde-boue avantSe reporter à la section “GUIDON”.
1 Ecrou de colonne de direction 1
2 Fourche avant 2 Se reporter à la section “FOURCHE AVANT”.
3Té supérieur 1
4 Ecrou crénelé de direction 1 Utiliser l’outil spécial.
Se reporter à “POINTS DE DEPOSE”.
5Té inférieur 1
6 Couvercle de cage à billes 1
7 Roulement supérieur 1
8 Roulement inférieur 1 Se reporter à “POINTS DE DEPOSE”.
9 Cage à billes 2 Se reporter à “POINTS DE DEPOSE”.
1
2
STERZO
Portata dello smontaggio:1 Rimozione della staffa inferiore 2 Rimozione del cuscinetto
OPERAZIONI DI SERRAGGIO:
Serrare la ghiera. 38 Nm (3,8 m • kg, 27 ft • lb)
Allentarla di un giro.
Riserrarla. 7 Nm (0,7 m • kg, 5,1 ft • lb)
Portata dello smontaggio Ordine Denominazione QuantitàOsservazioni
RIMOZIONE DELLO STERZO
AVVERTENZA
Sostenere saldamente il veicolo in modo che non ci siail rischio che si rovesci. Preparazione per la rimozione Mantenere il veicolo posizionando un supporto
idoneo sotto al motore.
Targa
Manubrio
Guidacavo
Parafango anterioreFare riferimento al paragrafo “MANUBRIO”.
1 Dado cannotto dello sterzo 1
2 Forcella anteriore 2Fare riferimento al paragrafo “FORCELLA ANTERIORE”.
3 Piastra superiore 1
4 Ghiera 1 Utilizzare l’utensile speciale.
Fare riferimento a “PUNTI DI RIMOZIONE”.
5 Piastra inferiore 1
6 Coperchio pista 1
7 Cuscinetto superiore 1
8 Cuscinetto inferiore 1 Fare riferimento a “PUNTI DI RIMOZIONE”.
9 Pista 2 Fare riferimento a “PUNTI DI RIMOZIONE”.
1
2

5 - 48
CHASSTEERING
4. Install:
Steering ring nut 1
Tighten the steering ring nut using the
steering nut wrench 2.
Refer to “STEERING HEAD INSPEC-
TION AND ADJUSTMENT” section in
the CHAPTER 3.
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
5. Check the steering stem by turning it lock
to lock. If there is any binding, remove
the steering stem assembly and inspect
the steering bearings.
6. Install:
Front fork 1
Upper bracket 2
NOTE:
Temporarily tighten the pinch bolts (lower
bracket).
Do not tighten the pinch bolts (upper bracket)
yet.
7. Install:
Washer 1
Steering stem nut 2
T R..145 Nm (14.5 m · kg, 105 ft · lb)
8. After tightening the nut, check the steer-
ing for smooth movement. If not, adjust
the steering by loosening the steering
ring nut little by little.
9. Adjust:
Front fork top end a
Front fork top end (standard) a:
5 mm (0.20 in)