2002 YAMAHA YZ250LC oil

4-28
CYLINDER HEAD, CYLINDER AND PISTONENG
4. Install:
9Spring 1 1
9Link lever 2
9Pulley 3
9Spring 2 4
9Plain washer 5
9Valve shaft 6
NOTE:
9Install the spring 1 to the link lever, and then to
the cylinder.
9Install the spring 1 with its stopper portion a
facing inward.
9Apply the molybdnum disulfide oil on the
grooves in the pulleys.
9Apply the lithium soap base grease on the oil
seal lip.
9Install the valve shaft with its cut baligning
with the thrust plate 7, and then rotate the
valve shaft so that its cut faces upward.
5. Install:
9Valve holder 1 1
9Bolt (link lever) 2
9Bolt (pulley) 3
NOTE:
First tighten the bolt (link lever), and then tighten
the bolts (pulleys).
6. Check:
9Power valve 1 smooth movement
Unsmooth movement Repair or
replace.
4 Nm (0.4 m•kg, 2.9 ft•lb)
4 Nm (0.4 m•kg, 2.9 ft•lb)
5NX-9-30-4B 6/7/01 1:56 PM Page 2

4-29
CYLINDER HEAD, CYLINDER AND PISTONENG
7. Install:
9O-ring 1
9Side holder 2
9Screw (side holder) 3
9YPVS breather hose 4
NOTE:
9Apply the lithium soap base grease on the O-
rings.
9Install the side holder with its projection a
facing upward.
8. Install:
9Gasket (power valve cover) 1
9Power valve cover 2
9Screw (power valve cover) 3
NOTE:
9Install the gasket with its cut afacing down-
ward and the seal print side toward the power
valve cover.
9Install the power valve cover so that the arrow
mark bfaces upward.
EC475233
Piston ring and piston
1. Install:
9Piston ring 1
NOTE:
9Take care not to scratch the piston or damage
the piston ring.
9Align the piston ring gap with the pin 2.
9After installing the piston ring, check the
smooth movement of it.
2. Install:
9Gasket (cylinder) 1
9Small end bearing 2
9Dowel pin 3
NOTE:
9Apply the engine oil onto the bearing (crank-
shaft and connecting rod) and connecting rod
big end washers.
9Install the gasket with the seal print side
toward the crankcase.
4 Nm (0.4 m•kg, 2.9 ft•lb)
4 Nm (0.4 m•kg, 2.9 ft•lb)
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4-30
CYLINDER HEAD, CYLINDER AND PISTONENG
EC475382
Cylinder head and cylinder
1. Apply:
9Engine oil
To piston 1piston ring 2and cylinder sur-
face.
2. Install:
9Cylinder 1
cC
Make sure the piston rings are properly
positioned. Install the cylinder with one
hand while compressing the piston rings
with the other hand.
NOTE:
After installing, check the smooth movement of
the piston.
3. Install:
9Nut (cylinder) 1
NOTE:
Tighten the nuts in stage, using a crisscross pat-
tern.
3. Install:
9Piston 1
9Piston pin 2
9Piston pin clip 3
NOTE:
9The arrow aon the piston dome must point to
exhaust side.
9Before installing the piston pin clip, cover the
crankcase with a clean rag to prevent the pis-
ton pin clip from falling into the crankcase cavi-
ty.
cC
Do not allow the clip open ends to meet the
piston pin slot b b
.
35 Nm (3.5 m•kg, 25 ft•lb)
5NX-9-30-4B 6/7/01 1:56 PM Page 6

4-33
CLUTCH AND PRIMARY DRIVEN GEARENG
Extent of removal Order Part name Q’ty Remarks
CLUTCH PLATE AND
FRICTION PLATE REMOVAL
Preparation for Drain the transmission oil.
Refer to “TRANSMISSION OIL REPLACE-
removalMENT“ section in the CHAPTER 3.
Bolt (brake pedal) Shift the brake pedal downward.
Rotor and stator Refer to
“CDI MAGNETO“section.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Screw (clutch spring) 6
3 Clutch spring 6
4 Pressure plate 1
5 Friction plate 8
6 Clutch plate 7
Extent of removal:1Clutch plate and friction plate removal
EC490000
CLUTCH AND PRIMARY DRIVEN GEAREC498000
CLUTCH PLATE AND FRICTION PLATE
1
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
5NX-9-30-4B 6/7/01 1:56 PM Page 12

4-36
CLUTCH AND PRIMARY DRIVEN GEARENG
EC484500
Friction plate
1. Measure:
9Friction plate thickness
Out of specification Replace friction
plate as a set.
Measure at all four points.
EC484600
Clutch plate
1. Measure:
9Clutch plate warpage
Out of specification Replace clutch plate
as a set.
Use a surface plate 1and thickness
gauge 2.
EC484700
Push lever axle
1. Inspect:
9Push lever axle 1
Wear/Damage Replace.
EC484810
Push rod
1. Inspect:
9Push rod 1 1
9Bearing 2
9Plain washer 3
9Push rod 2 4
Wear/Damage/Bend Replace.
EC495000
ASSEMBLY AND INSTALLATION
EC485120
Push lever axle
1. Install:
9Push lever axle 1
9Copper washer 2
9Bolt (push lever axle) 3
NOTE:
Apply the lithium soap base grease on the oil
seal lip and push lever axle.
Friction plate thickness:
Standard
2.9~3.1 mm 2.8 mm
(0.114~0.122 in) (0.110 in)
Warp limit:
0.2 mm (0.008 in)
6 Nm (0.6 m•kg, 4.3ft•lb)
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4-36
EMBRAYAGE ET PIGNON MENE PRIMAIRE
KUPPLUNG UND PRIMÄRABTRIEBSZAHNRAD
FRIZIONE E INGRANAGGIO CONDOTTO PRIMARIOENG
Schubstange
1. Prüfen:
9Schubstange 1 1
9Lager 2
9Beilegescheibe 3
9Schubstange 2 4
Abnutzung/Beschädigung/
Biegung Erneuern.IC484810Asta di spinta
1. Ispezionare:
9Asta di spinta 1 1
9Cuscinetto 2
9Rosetta 3
9Asta di spinta 2 4
Usura/Danni/CurvaturaSosti-
tuirli.
MONTAGE UND EINBAU
Schubhebelachse
1. Einbauen:
9Schubhebelachse 1
9Kupferscheibe 2
9Schrauben (Schubhebelachse)
3
HINWEIS:
Lithiumfett auf die Öldichtungslippe
und Schubhebelachse auftragen.
IC495000
MONTAGGIO E
INSTALLAZIONE
IC485120
Asse leva di spinta
1. Installare:
9Asse leva di spinta 1
9Rondella in rame 2
9Bullone (asse leva di spinta) 3
NOTA:
Applicare il grasso a base di sapone al
litio sul bordo del paraolio e spingere
l’asse della leva di spinta.
Reibscheibe
1. Messen:
9Reibscheibendicke
Abweichung von Spezifikation
Die Reibscheiben als Satz
erneuern.
Die Reibscheiben an vier Stel-
len messen.
Kuplungsscheibe
1. Messen:
9Verzug der Kupplungsschei-
ben
Abweichung von Spezifikation
Kupplungsscheiben als Satz
erneuern.
Eine Richtplatte 1und eine
Fühlerlehre 2verwenden.
Schubhebelachse
1. Prüfen:
9Schubhebelachse 1
Abnutzung/Beschädigung
Erneuern.Disque de friction
1. Mesurer:
9Epaisseur de disque de friction
Hors-spécificationChanger
tous les disques de friction.
Mesurer chaque disque en
quatre endroits.
Disque d’embrayage
1. Mesurer:
9Voile de disque d’embrayage
Hors-spécificationChanger
tous les disques d’embrayage.
Utiliser une plaque à surfacer 1
et une jauge d’épaisseur 2.
Axe de levier de poussée
1. Examiner:
9Axe de levier de poussée 1
Usure/endommagementChan-
ger.
Tige de poussée
1. Examiner:
9Tige de poussée 1 1
9Roulement 2
9Rondelle ordinaire 3
9Tige de poussée 2 4
Usure/endommagement/défor-
mationChanger.
REMONTAGE ET
MONTAGE
Axe de levier de poussée
1. Monter:
9Axe de levier de poussée 1
9Rondelle en cuivre 2
9Boulon (axe de levier de pous-
sée) 3
N.B.:
Appliquer de la graisse à base de sapo-
nification de lithium sur le joint à lèvre
et l’axe de levier de poussoir.
IC484500Disco di innesto
1. Misurare:
9Spessore del disco di innesto
Fuori specificaSostituire il
disco di innesto come set.
Misurare su tutti e quattro i
punti.
IC484600
Disco della frizione
1. Misurare:
9Svergolamento del disco della
frizione
Fuori specificaSostituire il
disco della frizione come set.
Usare un piano di riscontro 1e
uno spessimetro 2.
IC484700
Asse della leva di spinta
1. Ispezionare:
9Asse della leva di spinta 1
Usura/DanniSostituirlo.
Standard
2,9~3,1 mm 2,8 mm
(0,114~0,122 in) (0,110 in)
Reibscheibendicke:
Verzungsgrenze:
0,2 mm (0,008 in)
Valore normale
2,9~3,1 mm 2,8 mm
(0,114~0,122 in) (0,110 in)
Spessore del disco di inne-
sto:
Limite di svergolamento:
0,2 mm (0,008 in)
Limite de déformation:
0,2 mm (0,008 in)
Standard
2,9~3,1 mm 2,8 mm
(0,114~0,122 in) (0,110 in)
Epaisseur de disque de
friction:
6 Nm (0,6m•kg, 4,3 ft•lb)
6 Nm (0,6 m•kg, 4,3 ft•lb)6 Nm (0,6 m•kg, 4,3 ft•lb)
5NX-9-30-4B 6/7/01 1:56 PM Page 19

4-37
CLUTCH AND PRIMARY DRIVEN GEARENG
EC495230
Clutch
1. Install:
9Thrust plate [D=ø 42 mm (1.65 in)] 1
9Spacer 2
9Bearing 3
9Primary driven gear 4
NOTE:
Apply the transmission oil on the bearing, spacer
and primary driven gear inner circumference.
2. Install:
9Thrust plate [D=ø 44 mm (1.73 in)] 1
9Clutch boss 2
3. Install:
9Lock washer 1
9Nut (clutch boss) 2
NOTE:
Use the clutch holding tool 3, 4to hold the
clutch boss.
åFor USA and CDN
∫Except for USA and CDN
4. Bend the lock washer 1tab.
75 Nm (7.5 m•kg, 54 ft•lb)
Clutch holding tool:
YM-91042 ..............................3 3
90890-04086 ..........................4 4
å
∫
5NX-9-30-4B 6/7/01 1:56 PM Page 20

4-38
CLUTCH AND PRIMARY DRIVEN GEARENG
5. Install:
9Friction plate 1
9Clutch plate 2
NOTE:
9Install the clutch plates and friction plates alter-
nately on the clutch boss, starting with a friction
plate and ending with a friction plate.
9Apply the transmission oil on the friction plates
and clutch plates.
6. Install:
9Bearing 1
9Plain washer 2
9Circlip 3
To push rod 1 4.
NOTE:
Apply the lithium soap base grease on the bear-
ing and plain washer.
7. Install:
9Push rod 2 1
9Push rod 1 2
NOTE:
9Apply the transmission oil on the ends of the
push rod 2.
9Install the push rod 2 with its smaller end a
toward you.
8. Install:
9Pressure plate 1
9. Install:
9Clutch spring 1
9Screw (clutch spring) 2
NOTE:
Tighten the screws in stage, using a crisscross
pattern.
10 Nm (1.0 m•kg, 7.2 ft•lb)
5NX-9-30-4B 6/7/01 1:56 PM Page 22