2005 YAMAHA YZ125LC crankcase

4-63
ENGCRANKCASE AND CRANKSHAFT
EC4N3302
Crankshaft
1. Remove:
9Crankshaft 1
Use the crankcase separating tool 2.
NOTE:
Make appropriate bolts 3as shown available by
yourself and attach the tool with them.
cC
Do not use a hammer to drive out the
crankshaft.
EC4N3401
Crankshaft bearing
1. Remove:
9Bearing 1
NOTE:
9Remove the bearing from the crankcase by
pressing its inner race as shown in å.
9If the bearing is removed together with the
crankshaft, remove the bearing using a general
bearing puller 2as shown in ∫.
9Do not use the removed bearing.
EC4N4000
INSPECTION
EC4N4101
Crankcase
1. Inspect:
9Contacting surface a
Scratches Replace.
9Engine mounting boss b, crankcase
Cracks/Damage Replace.
Crankcase separating tool:
YU-1135-A/90890-01135
1C3-9-30-4D 25/5/04 7:15 PM Page 16

4-64
ENGCRANKCASE AND CRANKSHAFT
Standard
Runout 0.03 mm 0.05 mm
limit: (0.0012 in) (0.0020 in)
Small end 0.8~1.0 mm 2.0 mm
free play: (0.031~0.039 in) (0.08 in)
Side 0.06~0.64 mm
—
clearance: (0.002~0.025 in)
Crank 55.90~55.95 mm
—
width: (2.201~2.203 in)
2. Inspect:
9Bearings 1
Rotate inner race with a finger.
Rough spot/Seizure Replace.
3. Inspect:
9Oil seal 1
Damage Replace.
EC4N4202
Crankshaft
1. Measure:
9Runout limit a
9Small end free play limit b
9Connecting rod big end side clearance c
9Crank width d
Out of specification Replace.
Use the dial gauge and a thickness gauge.
EC4N5000
ASSEMBLY AND INSTALLATION
EC4N5300
Crankshaft bearing
1. Install:
9Bearing 1
To crankcase (left and right).
NOTE:
Install the bearing by pressing its outer race
parallel.
Dial gauge:
YU-3097/90890-01252
1C3-9-30-4D 25/5/04 7:15 PM Page 18

4-65
ENGCRANKCASE AND CRANKSHAFT
EC4N5102
Oil seal
1. Install:
9Oil seal (left) 1
9Oil seal (right) 2
NOTE:
9Apply the lithium soap base grease on the oil
seal lip.
9Install the oil seal with its manufacture’s marks
or numbers facing outward.
EC4N5272
Crankshaft
1. Install:
9Crankshaft 1
Use the crankshaft installing tool 2, 3, 4
åFor USA and CDN
∫Except for USA and CDN
NOTE:
9Hold 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 bear-
ing.
9Before installing the crankshaft, clean the con-
tacting surface of crankcase.
9Apply the lithium soap base grease on the oil
seal lip.
cC
Do not use a hammer to drive in the crank-
shaft.
Crankshaft installing tool:
Pot 2 2
:
YU-90050/90890-01274
Bolt 3 3
:YU-90050/90890-01275
Adapter 4 4
:YU-90063/90890-01278
å∫
1C3-9-30-4D 25/5/04 7:15 PM Page 20

4-66
ENGCRANKCASE AND CRANKSHAFT
2. Check:
9Shifter operation
9Transmission operation
Unsmooth operation Repair.
3. Apply:
9Sealant
On the crankcase (right) 1
NOTE:
Clean the contacting surface of crankcase (left
and right) before applying the sealant.
Quick gasket®:
ACC-QUICK-GS-KT
Yamaha bond No. 1215:
90890-85505
4. Install:
9Dowel pin 1
9O-ring 2
1C3-9-30-4D 25/5/04 7:15 PM Page 22

7. Install:
9Holder 1
9Bolt (holder) 2
4-67
ENGCRANKCASE AND CRANKSHAFT
6. Install:
9Clamp 1
9Bolt (crankcase) 2
NOTE:
Tighten the crankcase tightening bolts in stage,
using a crisscross pattern.
14 Nm (1.4 m•kg, 10 ft•lb)
5. Install:
9Crankcase (right) 1
Use the crankshaft installing tool 2, 3, 4.
ÅFor USA and CDN
ıExcept for USA and CDN
NOTE:
9Use two plain washers (Yamaha genuine:
90201-243K3) 5or the ones of a size as
shown one on the other. (Except for USA and
CDN)
9Install so that the plain washers do not deviate
from the crankshaft center. (Except for USA
and CDN)
9When installing the crankcase, the connecting
rod should be positioned at TDC (top dead
center).
9Install while checking that the dowel pin is in
place.
Crankshaft installing tool:
Pot 2:
YU-90050/90890-01274
Bolt 3:YU-90050/90890-01275
Adapter 4:YM-01499/90890-01499
10 Nm (1.0 m•kg, 7.2 ft•lb)
å∫
∫
1C3-9-30-4D 25/5/04 7:15 PM Page 24

8. Install:
9Segment 1
9Bolt (segment) 2
NOTE:
9When installing the segment onto the shift cam
3, align the punch mark awith the dowel pin
b.
9Turn the segment clockwise until it stops and
tighten the bolt.
9. Remove:
9Sealant
Forced out on the cylinder mating surface.
10. Apply:
9Engine oil
To the crank pin, bearing, oil delivery hole
and connecting rod big end washer.
11. Check:
9Crankshaft and transmission operation
Unsmooth operation Repair.
4-68
ENGCRANKCASE AND CRANKSHAFT
30 Nm (3.0 m•kg, 22 ft•lb)
1C3-9-30-4D 25/5/04 7:15 PM Page 26

4-69
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
Extent of removal Order Part name Q’ty Remarks
TRANSMISSION, SHIFT CAM AND
SHIFT FORK REMOVAL
Preparation for EngineRefer to “ENGINE REMOVAL” section.
removal Separate the crankcase. Refer to“CRANKCASE AND CRANK
SHAFT
” section.
1 Guide bar (long) 1
2 Guide bar (short) 1
3 Shift cam 1
4 Shift fork 3 1
5 Shift fork 1 1
6 Shift fork 2 1
7 Main axle 1
8 Drive axle 1Refer to “REMOVAL POINTS”.
9 Spacer 1
EC4H0000
TRANSMISSION, SHIFT CAM AND SHIFT FORK
Extent of removal:1Shift cam and shift fork removal2Main axle and drive axle removal
1
2



10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
1C3-9-30-4D 25/5/04 7:15 PM Page 28

4-72
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
2. Install:
92nd wheel gear (29T) 1
95th wheel gear (24T) 2
93rd wheel gear (27T) 3
94th wheel gear (23T) 4
96th wheel gear (23T) 5
91st wheel gear (31T) 6
To drive axle 7.
NOTE:
Apply the molybdenum disulfide oil on the inner
and end surface of the idler gear and on the
inner surface of the sliding gear, then install.
3. Install:
9Plain washer 1
9Circlip 2
NOTE:
9Be sure the circlip sharp-edged corner ais po-
sitioned opposite side to the plain washer and
gear b.
9Be sure the circlip end cis positioned at axle
spline groove d.
4. Install:
9Spacer 1
NOTE:
9Apply the lithium soap base grease on the oil
seal lip.
9When installing the spacer into the crankcase,
pay careful attention to the crankcase oil seal
lip.
1C3-9-30-4D 25/5/04 7:15 PM Page 34