2015 YAMAHA WR 250F Owners Manual

CRANKSHAFT ASSEMBLY AND BALANCER SHAFT
6-74
EAS2GB2320REMOVING THE CRANKSHAFT ASSEMBLY
1. Remove:
• Crankshaft assembly “1”
TIP
Remove the crankshaft assembly by using the
crankcase separating tool “2”.
EAS2GB2321CHECKING THE CRANKSHAFT ASSEMBLY
1. Measure:
• Crankshaft runout
Out of specification  Replace the crank-
shaft, bearing or both.
TIP
Turn the crankshaft slowly.2. Measure:
• Big end side clearance D “a”
Out of specification  Replace the big end
bearing, crankshaft pin, or connecting rod.
3. Measure:
• Crankshaft width A “a”
Out of specification  Replace the crank-
shaft.
4. Check:
• Crankshaft sprocket “1”
Damage  Replace the crankshaft.
5. Check:
• Crankshaft journal oil passage
Obstruction  Blow out with compressed
air. Crankcase separating tool
90890-04152
Crankcase separating tool
YU-A9642
Runout limit C
0.030 mm (0.0012 in)
2
1
Big end side clearance D
0.150–0.450 mm (0.0059–0.0177
in)
Width A
55.95–56.00 mm (2.203–2.205 in)
1

CRANKSHAFT ASSEMBLY AND BALANCER SHAFT
6-75
EAS2GB2322INSTALLING THE CRANKSHAFT ASSEM-
BLY
1. Install:
• Crankshaft assembly
TIP
Install the crankshaft assembly with the crank-
shaft installer pot “1”, crankshaft installer bolt
“2”, adapter (M12) “3” and spacer “4”.
ECA
NOTICE
• To avoid scratching the crankshaft and to
ease the installation procedure, lubricate
the oil seal lips with lithium-soap-based
grease.
• In order to prevent the crankshaft seizure,
apply molybdenum disulfide grease.
TIP
Hold the connecting rod at top dead center
(TDC) with one hand while turning the nut of the
crankshaft installer bolt with the other. Turn the
crankshaft installer bolt until the crankshaft as-
sembly bottoms against the bearing.
EAS2GB2323INSTALLING THE BALANCER SHAFT
1. Install:
• Balancer shaft “1”
TIP
Apply the molybdenum grease to the part “a”
where the balancer shaft fit into the bearing.
ECA
NOTICE
Do not apply the molybdenum grease to the
balancer shaft thread. Crankshaft installer pot
90890-01274
Installing pot
YU-90058
Crankshaft installer bolt
90890-01275
Bolt
YU-90060
Adapter (M12)
90890-01278
Adapter #3
YU-90063
Spacer (crankshaft installer)
90890-04081
Pot spacer
YM-91044
M
1
a

TRANSMISSION
6-76
EAS2GB2324
TRANSMISSION
Removing the transmission, shift drum assembly, and shift forks
Order Part name Q’ty Remarks
Engine Refer to “ENGINE REMOVAL” on page 6-1.
CrankcaseSeparate.
Refer to “CRANKCASE” on page 6-68.
1 Main axle 1
2 Drive axle 1
3 Long shift fork guide bar 1
4 Short shift fork guide bar 1
5Spring 4
6 Shift cam 1
7 Shift fork 3 (R) 1
8 Shift fork 2 (C) 1
9 Shift fork 1 (L) 1
10 Collar 1
For installation, reverse the removal proce-
dure.
2
10
1
53
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69
M
M
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M
M
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LS
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TRANSMISSION
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EAS2GB2325REMOVING THE TRANSMISSION
1. Remove:
• Long shift fork guide bar “1”
• Short shift fork guide bar “2”
• Shift cam “3”
• Shift fork 3 “4”
• Shift fork 2 “5”
• Shift fork 1 “6”
• Main axle “7”
• Drive axle “8”
• Collar “9”
TIP
• Remove assembly with the collar “9” installed
to the crankcase.
• Make a note of the position of each part. Pay
particular attention to the location and direc-
tion of shift forks.
• Remove the main axle and the drive axle all
together by tapping the drive axle lightly with
a soft hammer.
EAS2GB2326
CHECKING THE SHIFT FORKS
1. Check:
• Shift fork cam follower “1”
• Shift fork pawl “2”
Bends/damage/scoring/wear  Replace the
shift fork.
2. Check:
• Shift fork guide bar
Roll the shift fork guide bar on a flat surface.
Bends  Replace.
EWA
WARNING
Do not attempt to straighten a bent shift fork
guide bar.
3. Check:
• Shift fork movement
(along the shift fork guide bar)
Rough movement  Replace the shift forks
and shift fork guide bar as a set.
1
4
62
5
3
8
7
9

TRANSMISSION
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EAS2GB2327CHECKING THE SHIFT DRUM ASSEMBLY
1. Check:
• Shift drum groove
Damage/scratches/wear  Replace the
shift drum assembly.
• Shift drum segment “1”
Damage/wear  Replace the shift drum as-
sembly.
EAS2GB2328CHECKING THE TRANSMISSION
1. Measure:
• Main axle runout
(with a centering device and dial gauge “1”)
Out of specification  Replace the main ax-
le.
2. Measure:
• Drive axle runout
(with a centering device and dial gauge “1”)
Out of specification  Replace the drive ax-
le.3. Check:
• Transmission gears
Blue discoloration/pitting/wear  Replace
the defective gear (s).
• Transmission gear dogs
Cracks/damage/rounded edges  Replace
the defective gear (s).
4. Check:
• Transmission gear movement
Rough movement  Replace the defective
gear (s).
EAS2GB2329INSTALLING THE TRANSMISSION
1. Install:
• 6th pinion gear (27T) “1”
• 3rd/4th pinion gear (18T/21T) “2”
• Collar “3”
• 5th pinion gear (23T) “4”
• 2nd pinion gear (16T) “5”
(to the main axle “6”)
TIP
Before installation, apply molybdenum disulfide
oil to the inner and end surface of the idler gear
and to the inner surface of the sliding gear, then
install. Main axle runout limit
0.08 mm (0.0032 in)
Drive axle runout limit
0.08 mm (0.0032 in)
34
2
1
6
5
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TRANSMISSION
6-79
2. Install:
• 2nd wheel gear (29T) “1”
• 5th wheel gear (22T) “2”
• 3rd wheel gear (26T) “3”
• 4th wheel gear (24T) “4”
• 6th wheel gear (22T) “5”
• Collar “6”
• 1st wheel gear (31T) “7”
• O-ring “8”
(to the drive axle “9”)
TIP
• Before installation, apply molybdenum disul-
fide oil to the inner and end surface of the idler
gear and to the inner surface of the sliding
gear, then install.
• Apply the lithium-soap-based grease on the
O-ring.
3. Install:
• Washer “1”
• Circlip “2”
TIP
• Be sure the circlip sharp-edged corner “a” is
positioned opposite side to the washer and
gear “b”.
• Install the circlip with its ends “c” settled even-
ly on the spline crests.4. Install:
• Collar “1”
TIP
• Apply the lithium-soap-based grease on the
oil seal lip.
• When installing the collar into the crankcase,
pay careful attention to the crankcase oil seal
lip.
5. Install:
• Main axle “1”
• Drive axle “2”
TIP
• Install to the left crankcase simultaneously.
• Apply engine oil to the main axle and the drive
axle bearing.
New
891
234
567M
New
LS
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ab
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TRANSMISSION
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6. Install:
• Shift fork 1 (L) “1”
• Shift fork 2 (C) “2”
• Shift fork 3 (R) “3”
• Shift cam “4”
(to the main axle and the drive axle)
TIP
• Apply engine oil to the shift fork grooves.
• Apply engine oil to the shift cam groove and
the bearing contact surface.
• Mesh the shift fork 1 (L) with the 5th wheel
gear “5” and “3” (R) with the 6th wheel gear “7”
on the drive axle.
• Mesh the shift fork 2 (C) with the 3rd/4th pin-
ion gear “6” on the main axle.7. Install:
• Long shift fork guide bar “1”
• Short shift fork guide bar “2”
• Spring “3”
TIP
• Screw the spring into the shift fork guide bar
lightly beforehand.
• Apply the engine oil on the shift fork guide
bars.
8. Check:
• Operation of shift cam and shift fork
• Transmission operation
Unsmooth operation  Repair.
3
12
6
2
4
5
3
7
1
E
E
E
2 13
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TRANSMISSION
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