clutch YAMAHA YZ426F 2000 Owner's Manual

4 - 43
ENG

CLUTCH
EC493000
REMOVAL POINTS
EC483211
Clutch boss
1. Remove:
l
Nut
1

l
Lock washer
2

l
Clutch boss
3

NOTE:

Straighten the lock washer tab and use the
clutch holding tool
4
to hold the clutch boss.

For USA and CDN
õ
Except for USA and CDN
Clutch holding tool:
YM-91042/90890-04086

õ

EC494000
INSPECTION
EC484100
Clutch housing and boss
1. Inspect:
l
Clutch housing
1

Cracks/wear/damage
®
Replace.
l
Clutch boss
2

Scoring/wear/damage
®
Replace.
EC484201
Primary driven gear
1. Check:
l
Circumferential play
Free play exists
®
Replace.
l
Gear teeth
a

Wear/damage
®
Replace.
EC484400
Clutch spring
1. Measure:
l
Clutch spring free length
a

Out of specification
®
Replace springs
as a set.
Clutch spring free length:
Standard
44 mm
(1.73 in)43 mm
(1.69 in)

4 - 44
ENG

CLUTCH
EC484500
Friction plate
1. Measure:
l
Friction plate thickness
Out of specification
®
Replace friction
plate as a set.
Measure at all four points.
EC484600
Clutch plate
1. Measure:
l
Clutch plate warpage
Out of specification
®
Replace clutch
plate as a set.
Use a surface plate
1
and thickness
gauge
2
.
Push lever
1. Inspect:
l
Push lever
1

Wear/damage
®
Replace.
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)
EC484810
Push rod
1. Inspect:
l
Push rod 1
1

l
Bearing
2

l
Plain washer
3

l
Push rod 2
4

Wear/damage/bend
®
Replace.
EC495000
ASSEMBLY AND INSTALLATION
Push lever
1. Install:
l
Push lever
1

NOTE:

Apply the engine oil on the oil seal lip and push
lever.

4 - 45
ENG

CLUTCH
EC495221
Clutch
1. 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
2. Bend the lock washer 1 tab.
3. Install:
lFriction plate 1
lClutch plate 2
NOTE:
lInstall the clutch plates and friction plates
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.
4. 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 - 46
ENGCLUTCH
5. Install:
lPush rod 2 1
lPush rod 1 2
NOTE:
Apply the engine oil on the push rod 1,2.
6. Install:
lPressure plate 1
7. 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)
8. Install:
lGasket (clutch cover) 1
lDowel pin 2
New
9. 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)

ENG
4 - 47
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 (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 in the CHAPTER 3.
Brake pedal Refer to “ENGINE REMOVAL” section.
Clutch cover Refer to “CLUTCH” section.
1 Oil filter cover 1
Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
2 Oil filter 1
3 Coolant pipe 2 1
4 Water pump housing 1
5 Pin 2
6 Oil delivery pipe 1
1
23

ENG
4 - 53
BALANCER
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 Straight key 1
7 Lock washer 1
8 Balancer driven gear 1
9Balancer
1
2
1
2

ENG
4 - 56
OIL PUMP
OIL PUMP
OIL PUMP
Extent of removal:1 Oil pump removal2 Oil pump disassembly
Extent of removal Order Part name Q’ty Remarks
OIL PUMP REMOVAL AND DIS-
ASSEMBLY
Preparation for removal Clutch housingRefer 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

ENG
4 - 71
ENGINE 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.
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.
WARNING
Support the machine securely so there is nodanger of it falling over.

ENG
4 - 76
CRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
Extent of removal:1 Crankcase separation2 Crank removal
Extent of removal Order Part name Q’ty Remarks
CRANKCASE SEPARATION
Preparation for removal EngineRefer to “ENGINE REMOVAL” section.
PistonRefer to “CYLINDER AND PISTON” sec-
tion.
BalancerRefer to “BALANCER” section.
Kick axle assembly
Refer to “KICK AXLE AND SHIFT
SHAFT” section.
Segment
StatorRefer to “CDI MAGNETO” section.
1 Timing chain guide (rear) 1
2 Timing chain 1
3 Bolt (40 mm) 3
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
Use special tool.
Refer to “REMOVAL POINTS”.
10 Crankcase (left) 1
21

4 - 79
ENGCRANKCASE AND CRANKSHAFT
REMOVAL POINTS
EC4N3210
Crankcase
1. Separate:
lCrankcase (right)
lCrankcase (left)
Separation steps:
lRemove the crankcase bolts, hose guide
and clutch cable holder.
lRemove the crankcase (right).
lRemove the dowel pins and O-ring.
NOTE:
Loosen each bolt 1/4 of a turn at a time and
after all the bolts are loosened, remove
them.
NOTE:
lFor this removal, slits in the crankcase.
lAs pressure is applied, alternately tap on
the transmission shafts, shift cam and
crankshaft.
CAUTION:
Use soft hammer to tap on the case half.
Tap only on reinforced portions of case.
Do not tap on gasket mating surface.
Work slowly and carefully. Make sure the
case halves separate evenly. If one end
“hangs up”, take pressure off the push
screw, realign, and start over. If the
cases do not separate, check for a
remaining case screw or fitting. Do not
force.