2005 YAMAHA YZ250LC oil

4-67
CRANKCASE AND CRANKSHAFTENG
EC4N4000
INSPECTION
EC4N4101
Crankcase
1. Inspect:
9Contacting surface a
Scratches
Replace.
9Engine mounting boss b, crankcase
Cracks/Damage
Replace.
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.
2. Inspect:
9Bearings 1
Rotate inner race with a finger.
Rough spot/Seizure
Replace.
3. Inspect:
9Oil seal 1
Damage
Replace.
1P8-9-30-4C 21/5/04 1:00 PM Page 36

4-68
CRANKCASE AND CRANKSHAFTENG
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.
Standard
Runout 0.03 mm 0.05 mm
limit: (0.0012 in) (0.0020 in)
Small end 0.4~1.0 mm 2.0 mm
free play: (0.016~0.039 in) (0.08 in)
Side 0.25~0.75 mm
—
clearance: (0.010~0.030in)
Crank 59.95~60.00 mm
—
width: (2.360~2.362 in)
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.
Dial gauge:
YU-3097/90890-01252
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.
1P8-9-30-4C 21/5/04 1:00 PM Page 38

4-69
CRANKCASE AND CRANKSHAFTENG
EC4N5284
Crankshaft
1. Install:
9Crankshaft 1
Use the crankshaft installing tool 2, 3, 4.
Crankshaft installing tool:
Pot 2:
YU-90050/90890-01274
Bolt 3:YU-90050/90890-01275
Adapter 4:YU-90063/90890-01278
2. Check:
9Shifter operation
9Transmission operation
Unsmooth operation
Repair.
å åBåFor 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.
1P8-9-30-4C 21/5/04 1:00 PM Page 40

4-70
CRANKCASE AND CRANKSHAFTENG
3. Install:
9O-ring 1
To crankcase (right) 2.
5. Install:
9Dowel pin 1
9Crankcase (right) 2
To crankcase (left) 3.
NOTE:
9Fit the crankcase (right) onto the crankcase
(left). Tap lightly on the case with soft hammer.
9When installing the crankcase, the connecting
rod should be positioned at TDC (top dead
center).
cC
In order to prevent the oil seal lipa a
from
being turned up or damaged, wrap a vinyl
tape or the likeb b
around the right end of
the crankshaft and apply the lithium soap
base grease over the tape.
NOTE:
Clean the contacting surface of crankcase (left
and right) before applying the sealant.
4. Apply:
9Sealant
On the crankcase (right) 1.
Quick gasket®:
ACC-QUICK-GS-KT
Yamaha bond No. 1215:
90890-85505
1P8-9-30-4C 21/5/04 1:00 PM Page 42

4-71
CRANKCASE AND CRANKSHAFTENG
8. Tighten:
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.
30 Nm (3.0 m•kg, 22 ft•lb)
7. Install:
9Tension spring 1
9Holder 2
9Bolt (holder) 3
NOTE:
Install the holder so that it contacts the projec-
tion aon the crankcase (right).
10 Nm (1.0 m•kg, 7.2 ft•lb)
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.
14 Nm (1.4 m•kg, 10 ft•lb)
6. Install:
9Bolt (crankcase) 1
NOTE:
Tighten the crankcase tightening bolts in stage,
using a crisscross pattern.
1P8-9-30-4C 21/5/04 1:00 PM Page 44

4-74
TRANSMISSION, SHIFT CAM AND SHIFT FORKENG
EC4H5000
ASSEMBLY AND INSTALLATION
EC4H5242
Transmission
1. Install:
95th pinion gear (21T) 1
93rd pinion gear (18T) 2
9Collar 3
94th pinion gear (22T) 4
92nd pinion gear (15T) 5
To main axle 6.
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. Check:
9Shift 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.
2. Inspect:
9Shift cam 1
9Segment 2
Wear/Damage
Replace.
EC4H4810
Shift fork, shift cam and segment
1. Inspect:
9Shift fork 1
Wear/Damage/Scratches
Replace.
1P8-9-30-4C 21/5/04 1:00 PM Page 50

4-75
TRANSMISSION, SHIFT CAM AND SHIFT FORKENG
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.
9Install the spacer with its chamfered side a
facing the crankcase.
3. Install:
9Plain washer 1
9Circlip 2
NOTE:
9Be sure the circlip sharp-edged corner ais
positioned opposite side to the plain washer
and gear b.
9Be sure the circlip end cis positioned at axle
spline groove d.
2. Install:
92nd wheel gear (23 T) 1
94th wheel gear (24 T) 2
93rd wheel gear (23 T) 3
95th wheel gear (20 T) 4
91st wheel gear (27 T) 5
9O-ring 6
To drive axle 7.
NOTE:
9Apply 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.
9Apply the lithium soap base grease on the O-
ring.
1P8-9-30-4C 21/5/04 1:00 PM Page 52

4-76
TRANSMISSION, SHIFT CAM AND SHIFT FORKENG
5. Install:
9Shift fork 1 (L) 1
9Shift fork 2 (C10) 2
9Shift fork 3 (R) 3
9Shift cam 4
To main axle and drive axle.
NOTE:
9Apply the molybdenum disulfide oil on the shift
fork grooves.
9Mesh the shift fork #1 (L) with the 4th wheel
gear 5and #3 (R) with the 5th wheel gear 7
on the drive axle.
9Mesh the shift fork #2 (C10) with the 3rd pinion
gear 6on the main axle.
6. Install:
9Transmission assembly 1
To crankcase (left) 2.
NOTE:
Apply the transmission oil on the bearings and
guide bars.
7. Check:
9Shifter operation
9Transmission operation
Unsmooth operation
Repair.
1P8-9-30-4C 21/5/04 1:00 PM Page 54