Yamaha WR450F(R) Owner's Service Manual page 216

CRANKCASE AND CRANKSHAFT
Crankshaft
Do not use a hammer to drive out the
crankshaft.
Crankshaft bearing
NOTE:
G
G
INSPECTION
Timing chain and timing chain guide
EC4N4101
Crankcase
4 - 93
1. Remove:
Crankshaft 1
G
Use the crankcase separating tool 2.
Crankcase separating tool:
YU-1135-A/90890-01135
CAUTION:
1. Remove:
Bearing 1
G
Remove the bearing from the crankcase by
pressing its inner race.
Do not use the removed bearing.
1. Inspect:
Timing chain
G
Cracks/stiff → Replace the timing chain
and camshaft sprocket as a set.
2. Inspect:
Timing chain guide
G
Wear/damage → Replace.
1. Inspect:
Contacting surface a
G
Scratches → Replace.
Engine mounting boss b, crankcase
G
Cracks/damage → Replace.
2. Inspect:
Bearing
G
Rotate inner race with a finger.
Rough spot/seizure → Replace.
3. Inspect:
Oil seal
G
Wear/damage → Replace.
ENG