clutch YAMAHA YZ426F 2001 Owner's Manual

4 - 47
ENGCLUTCH
EC493000
REMOVAL POINTS
EC483211
Clutch boss
1. Remove:
lNut 1
lLock washer 2
lClutch boss 3
NOTE:
Straighten the lock washer tab and use the
clutch holding tool 4 to hold the clutch boss.
For USA and CDN
õExcept for USA and CDN
Clutch holding tool:
YM-91042/90890-04086

õ
EC494000
INSPECTION
EC484100
Clutch housing and boss
1. Inspect:
lClutch housing 1
Cracks/wear/damage ® Replace.
lClutch boss 2
Scoring/wear/damage ® Replace.
EC484201
Primary driven gear
1. Check:
lCircumferential play
Free play exists ® Replace.
lGear teeth a
Wear/damage ® Replace.
EC484400
Clutch spring
1. Measure:
lClutch spring free length a
Out of specification ® Replace springs
as a set.
Clutch spring free length:
Standard
50 mm (1.97 in) 49 mm (1.93 in)

4 - 48
ENGCLUTCH
EC484500
Friction plate
1. Measure:
lFriction plate thickness
Out of specification ® Replace friction
plate as a set.
Measure at all four points.
EC484600
Clutch plate
1. Measure:
lClutch plate warpage
Out of specification ® Replace clutch
plate as a set.
Use a surface plate 1 and thickness
gauge 2.
Friction plate thickness:
2.9 ~ 3.1 mm
(0.114 ~ 0.122 in)
: 2.7 mm (0.106 in)
Warp limit:
0.1 mm (0.004 in)
Push lever
1. Inspect:
lPush lever 1
Wear/damage ® Replace.
EC484810
Push rod
1. Inspect:
lPush rod 1 1
lBearing 2
lPlain washer 3
lPush rod 2 4
lBall 5
Wear/damage/bend ® Replace.

4 - 49
ENGCLUTCH
EC4A5000
ASSEMBLY AND INSTALLATION
Push lever
1. Install:
lPush lever 1
lBolt (push lever)
NOTE:
lApply the lithium soap base grease on the oil
seal lip.
lApply the engine oil on the push lever.
lFit the seat plate 2 in the groove a of the
push lever 1 and tighten the bolt (seat
plate).
2
1
a
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
Clutch
1. Install:
lSeat plate 1
lClutch damper spring 2
lFriction plate 1 [d = ø128 mm (5.04 in)]
3
lClutch plate 4
To clutch boss 5.
NOTE:
lInstall the clutch damper spring with the
“OUT SIDE” mark a facing out.
lInstall the clutch plate with its sharp-edged
corner side b facing the engine.
4 3 2 1 5
a
b
3
5
1
243
1
2
4
2. Install:
lPrimary driven gear 1
lThrust washer 2
lClutch boss 3
NOTE:
Apply the engine oil on the primary driven gear
inner circumference.

4 - 50
ENGCLUTCH
3. Install:
lLock washer 1
lNut (clutch boss) 2
NOTE:
Use the clutch holding tool 3 to hold the clutch
boss.
For USA and CDN
õExcept for USA and CDN
Clutch holding tool:
YM-91042/90890-04086
New
T R..75 Nm (7.5 m · kg, 54 ft · lb)

õ
4. Bend the lock washer 1 tab.
5. Install:
lFriction plate 2 [d = ø119 mm (4.69 in)]
1
lClutch plate 2
NOTE:
lInstall the clutch plates and friction plates 2
alternately on the clutch boss, starting with a
friction plate and ending with a friction plate.
lApply the engine oil on the friction plates and
clutch plates.
6. Install:
lBearing 1
lPlain washer 2
lCirclip 3
To push rod 1 4.
NOTE:
Apply the engine oil on the bearing and plain
washer.
New

4 - 51
ENGCLUTCH
7. Install:
lPush rod 2 1
lBall 2
lPush rod 1 3
NOTE:
Apply the engine oil on the push rod 1, 2 and
ball.
8. Install:
lPressure plate 1
9. Install:
lClutch spring
lBolt (clutch spring)
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
T R..8 Nm (0.8 m · kg, 5.8 ft · lb)
10. Install:
lGasket (clutch cover) 1
lDowel pin 2
New
11. Install:
lClutch cover 1
lBolt (clutch cover)
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 52
ENG
OIL FILTER, WATER PUMP AND CRANKCASE COVER
(RIGHT)
OIL FILTER, WATER PUMP AND CRANKCASE COVER (RIGHT)
OIL FILTER, WATER PUMP AND CRANKCASE COVER (RIGHT)
Extent of removal:1 Oil filter removal2 Water pump removal
3 Crankcase cover (right) removal
Extent of removal Order Part name Q’ty Remarks
OIL FILTER, WATER PUMP
AND CRANKCASE COVER
(RIGHT) REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Drain the coolant. Refer to “COOLANT REPLACEMENT”
section in the CHAPTER 3.
Exhaust pipe Refer to “EXHAUST PIPE AND
SILENCER” section.
Brake pedal Refer to “ENGINE REMOVAL” section.
Clutch cover Refer to “CLUTCH” section.
1 Oil filter cover 1
2 Oil filter 1
3 Coolant pipe 2 1
4 Water pump housing 1
5 Pin 2
6 Oil delivery pipe 1
1
2
3

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ENGBALANCER
BALANCER
BALANCER
Extent of removal:1 Balancer drive gear2 Balancer
Extent of removal Order Part name Q’ty Remarks
BALANCER REMOVAL
Preparation for removal Clutch housing Refer to “CLUTCH” section.
Crankcase cover (right)Refer to “OIL FILTER, WATER PUMP AND
CRANKCASE COVER (RIGHT)” section.
Stator Refer to “CDI MAGNETO” section.
1 Nut (primary drive gear) 1
Refer to “REMOVAL POINTS”.
2 Nut (balancer) 1
3 Lock washer 1
4 Primary drive gear 1
5 Balancer drive gear 1
6 Lock washer 1
7 Balancer driven gear 1
8 Balancer 1 Refer to “REMOVAL POINTS”.
2
1
2

4 - 62
ENG

OIL PUMP
OIL PUMP
OIL PUMP
Extent of removal:
1
Oil pump removal
2
Oil pump disassembly
Extent of removal Order Part name Q’ty Remarks
OIL PUMP REMOVAL AND DIS-
ASSEMBLY
Preparation for removal Clutch housing Refer to “CLUTCH” section.
Crankcase cover (right)Refer to “OIL FILTER, WATER PUMP AND
CRANKCASE COVER (RIGHT)” section.
1 Circlip 1
2 Plate washer 1
3 Oil pump drive gear 1
4 Oil pump assembly 1
5 Dowel pin 1
6 Outer rotor 2 1
7 Circlip 1
8 Inner rotor 2 1
9 Pin 1
10 Oil pump cover 1
11 Outer rotor 1 1
12Inner rotor 1
1
2
1

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ENGENGINE REMOVAL
EC4M0000
ENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the frame.
WARNING
Support the machine securely so there is no
danger of it falling over.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Decompression cable and guide Disconnect at engine side.
Radiator Refer to “RADIATOR” section.
Shift pedal Refer to “CDI MAGNETO” section.
Cylinder head breather hose and
oil tank breather hoseRefer to “CAMSHAFTS” section.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Spark plug cap
Disconnect the CDI magneto lead.

4 - 82
ENGCRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
Extent of removal:1 Crankcase separation2 Crankshaft removal
Extent of removal Order Part name Q’ty Remarks
CRANKCASE SEPARATION
Preparation for removal Engine Refer to “ENGINE REMOVAL” section.
Piston Refer to “CYLINDER AND PISTON” sec-
tion.
Balancer Refer to “BALANCER” section.
Kick axle assembly
Refer to “KICK AXLE AND SHIFT
SHAFT” section.
Segment
Stator Refer to “CDI MAGNETO” section.
1 Timing chain guide (rear) 1
2 Timing chain 1
3 Bolt (40 mm) 3
Refer to “REMOVAL POINTS”. 4 Bolt (50 mm) 4
5 Bolt (60 mm) 2
6 Bolt (75 mm) 3
7 Hose guide 1
8 Clutch cable holder 1
9 Crankcase (right) 1
10 Crankcase (left) 1
21