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EAS25550
DISASSEMBLING THE CRANKCASE
1. Place the engine upside down.
2. Remove:
• Crankcase bolts
TIP
• Loosen each bolt 1/4 of a turn at a time, in
stages and in a crisscross pattern. After all of
the bolts are fully loosened, remove them.
• Loosen the bolts in decreasing numerical
order (refer to the numbers in the illustration).
• The numbers embossed on the crankcase
indicate the crankcase tightening sequence.
3. Remove:
• Lower crankcase
ECA13900
Tap on one side of the crankcase with a
soft-face hammer. Tap only on reinforced
portions of the crankcase, not on the
crankcase mating surfaces. Work slowly
and carefully and make sure the crankcase
halves separate evenly.
4. Remove:
• Dowel pins
5. Remove:
• Crankshaft journal lower bearing
(from the lower crankcase)
TIP
Identify the position of each part very carefully
so that it can be reinstalled in its original place.
EAS25580
CHECKING THE CRANKCASE
1. Thoroughly wash the crankcase halves in a
mild solvent.
2. Thoroughly clean all the gasket surfaces
and crankcase mating surfaces.
3. Check:
• Crankcase
Cracks/damage → Replace.
• Oil delivery passages
Obstruction → Blow out with compressed
air.
EAS25650
ASSEMBLING THE CRANKCASE
1. Lubricate:
• Crankshaft journal bearing inner surface
(with the recommended lubricant)
Recommended lubricant
Engine oil
2. Apply:
• Sealant
(onto the crankcase mating surfaces)
Yamaha bond No.1215
(Three bond No.1215®)
90890-85505
TIP
• Do not allow any sealant to come into con-
tact with the oil gallery or crankshaft journal
bearings. Do not apply sealant to within 2–3
mm (0.08–0.12 in) of the crankshaft journal
bearings.
• For area "a", apply Yamaha bond No.1215
(Three Bond No.1215®) twice. For shaded
area "b", degrease the area and then apply
Three Bond No.1280B.
A. Lower crankcase
B. Upper crankcase
3. Install:
• Dowel pins
4. Set the shift drum assembly and transmis-
sion gears in the neutral position.
5-67
CRANKCASE
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