2000 YAMAHA YZ426F oil

ENG
4 - 78
CRANKCASE AND CRANKSHAFT
CRANKCASE BEARING
Extent of removal Order Part name Q’ty Remarks
CRANKCASE BEARING
REMOVAL
Preparation for removal Transmission
Shift cam and shift forkRefer to “TRANSMISSION, SHIFT
CAM, SHIFT FORK” section.
1 Oil seal 3
2 Bearing 10

4 - 81
ENG

CRANKCASE AND CRANKSHAFT
EC4N4101
Crankcase
1. Inspect:
l
Contacting surface
a

Scratches
®
Replace.
l
Engine mounting boss
b
, crankcase
Cracks/damage
®
Replace.
2. Inspect:
l
Bearing
Rotate inner race with a finger.
Rough spot/seizure
®
Replace.
3. Inspect:
l
Oil seal
Wear/damage
®
Replace.
EC4N4201
Crankshaft
1. Measure:
l
Runout limit
a

l
Small end free play limit
b

l
Connecting rod big end side clearance
c

l
Crank width
d

Out of specification
®
Replace.
Use the dial gauge and a thickness
gauge.
Dial gauge and stand:
YU-03097/90890-01252
Standard
Runout
limit:0.03 mm
(0.0012 in)0.05 mm
(0.002 in)
Small end
free play:0.4 ~ 1.0 mm
(0.016 ~ 0.039 in)2.0 mm
(0.08 in)
Side
clearance:0.15 ~ 0.45 mm
(0.0059 ~ 0.0177 in)—
Crack
width:61.95 ~ 62.00 mm
(2.439 ~ 2.441 in)—

4 - 82
ENG

CRANKCASE AND CRANKSHAFT
Oil strainer
1. Inspect:
l
Oil strainer
Damage
®
Replace.
Oil delivery pipe
1. Inspect:
l
Oil delivery pipe
Cracks/damage
®
Replace.
l
Oil delivery pipe holes
1
Clogged
®
Blow out with compressed
air.
EC4N5000
ASSEMBLY AND INSTALLATION
EC4N5300
Crankshaft bearing
1. Install:
l
Bearing
l
Bearing stopper
l
Screw (bearing stopper)
To crankcase (left and right).
NOTE:

Install the bearing by pressing its outer race
parallel.
EC4N5223
Crankshaft
1. Install:
l
Crankshaft
1

Use the crankshaft installing tool
2
,
3
,
4
,
5
.

For USA and CDN
õ
Except for USA and CDN
Crankshaft installing tool:
Pot
2
:
YU-90050/90890-01274
Bolt
3
:
YU-90050/90890-01275
Adapter
4
:
YU-90062/90890-01277
Spacer
5
:
YM-91044/90890-04081
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

õ

4 - 83
ENG

CRANKCASE AND CRANKSHAFT
NOTE:

l
Hold the connecting rod at top dead center
with one hand while turning the nut of the
installing tool with the other. Operate the
installing tool until the crankshaft bottoms
against the bearing.
l
Before installing the crankshaft, clean the
contacting surface of crankcase.
CAUTION:

Do not use a hammer to drive in the crank-
shaft.
2. Check:
l
Shifter operation
l
Transmission operation
Unsmooth operation
®
Repair.
3. Install:
l
Oil strainer
1

l
Bolt (oil strainer)
2

T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4. Apply:
l
Sealant
On the crankcase (right)
1
.
NOTE:

Clean the contacting surface of crankcase (left
and right) before applying the sealant.
Quick gasket
®

:
ACC-11001-05-01
Yamaha bond No. 1215:
90890-85505

4 - 84
ENG

CRANKCASE AND CRANKSHAFT
5. Install:
l
Dowel pin
1

lO-ring 2
lCrankcase (right)
To crankcase (left).
NOTE:
lFit the crankcase (right) onto the crankcase
(left). Tap lightly on the case with soft ham-
mer.
lWhen installing the crankcase, the connect-
ing rod should be positioned at TDC (top
dead center).
6. Tighten:
lHose guide 1
lClutch cable holder 2
lBolt (crankcase)
NOTE:
Tighten the crankcase tightening bolts in
stage, using a crisscross pattern.
7. Install:
lOil delivery pipe
lO-ring
lBolt (oil delivery pipe)
8. Install:
lTiming chain
lTiming chain guide (rear)
lPlate washer
lBolt (timing chain guide)
9. Remove:
lSealant
Forced out on the cylinder mating sur-
face.
10. Apply:
lEngine oil
To the crank pin, bearing and oil deliv-
ery hole.
11. Check:
lCrankshaft and transmission operation.
Unsmooth operation ® Repair.
New
T R..12 Nm (1.2 m · kg, 8.7 ft · lb)
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 87
ENGTRANSMISSION, SHIFT CAM, SHIFT FORK
EC4H4801
Shift fork, shift cam and segment
1. Inspect:
lShift fork 1
Wear/damage/scratches ® Replace.
2. Inspect:
lShift cam 1
lSegment 2
Bend/wear/damage ® Replace.
3. Check:
lShift fork movement
Unsmooth operation ® Replace shift
fork.
NOTE:
For a malfunctioning shift fork, replace not only
the shift fork itself but the two gears each adja-
cent to the shift fork.
EC4H5212
Transmission
1. Install:
l5th pinion gear (21T) 1
l3rd pinion gear (18T) 2
lCollar 3
l4th pinion gear (22T) 4
l2nd pinion gear (18T) 5
To main axle 6.
NOTE:
lApply the molybdenum disulfide oil on the
4th and 5th pinion gears inner circumference
and on the end surface.
lApply the molybdenum disulfide oil on the
2nd and 3rd pinion gears inner circumfer-
ence.

4 - 88
ENGTRANSMISSION, SHIFT CAM, SHIFT FORK
2. Install:
l2nd wheel gear (27T) 1
l4th wheel gear (24T) 2
l3rd wheel gear (23T) 3
l5th wheel gear (20T) 4
l1st wheel gear (24T) 5
lO-ring 6
To drive axle 7.
NOTE:
lApply the molybdenum disulfide oil on the
1st, 2nd and 3rd wheel gears inner circum-
ference and on the end surface.
lApply the molybdenum disulfide oil on the
4th and 5th wheel gears inner circumfer-
ence.
lApply the lithium soap base grease on the O-
ring.
3. Install:
lPlain washer 1
lCirclip 2
NOTE:
lBe sure the circlip sharp-edged corner a is
positioned opposite side to the plain washer
and gear b.
lBe sure the circlip end c is positioned at
axle spline groove d.
New
4. Install:
lSpacer 1
NOTE:
lApply the lithium soap base grease on the oil
seal lip.
lWhen installing the spacer into the crank-
case, pay careful attention to the crankcase
oil seal lip.

4 - 89
ENGTRANSMISSION, SHIFT CAM, SHIFT FORK
5. Install:
lShift fork 1 (L) 1
lShift fork 2 (C) 2
lShift fork 3 (R) 3
lShift cam 4
To main axle and drive axle.
NOTE:
lApply the molybdenum disulfide oil on the
shift fork grooves.
lMesh the shift fork #1 (L) with the 4th wheel
gear 5 and #3 (R) with the 5th wheel gear
7 on the drive axle.
lMesh the shift fork #2 (C) with the 3rd pinion
gear 6 on the main axle.
6. Install:
lTransmission assembly 1
To crankcase (left) 2.
NOTE:
Apply the engine oil on the bearings and guide
bars.
7. Check:
lShifter operation
lTransmission operation
Unsmooth operation ® Repair.