13. Inspect the drive chain (B,
Figure 72
) for ex-
cessive wear or damage. If necessary, replace the
chain along with both the drive and driven
sprocket.
CRANKCASE
The following Yamaha special tools, or their
equivalents, are needed to service the crankcase:
1. Crankcase separating tool (part No. YU-01135-A
or 90890-01135).
2. Crankshaft installer pot (part No. YU-90058 or
90890-01274).
3. Crankshaft installer bolt (part No. YU-90060 or
90890-01275).
4. Adapter (part No. YM-4059 or 90890-04130).
5. Spacer (part No. YU-90070 or 90890-04060).
Crankcase Disassembly
This procedure describes the separation of the
crankcase halves, and the removal of the crank-
shaft, transmission shaft assemblies and the internal
shift mechanism. Disassembly and inspection pro-
cedures for the transmission shaft assemblies, mid-
dle driven gear and internal shift mechanism are in
Chapter Seven. Removal/installation, disassem-
bly/assembly and inspection procedures for the
middle drive assembly and the middle driven
assembly also appear in Chapter Seven.
1. Remove the engine as described in this chapter.
2. Remove the following exterior assemblies from
the crankcase as described in the respective
chapters:
a. Oil filter (Chapter Three).
b. Cylinder head (Chapter Four).
c. Cam chain and chain guides (Chapter Four).
d. Cylinder and piston (Chapter Four).
e. Clutch (Chapter Six).
f. Primary drive gear (Chapter Six).
g. Flywheel (this chapter).
h. Oil pump (this chapter).
i. External shift mechanism (Chapter Seven).
3. Remove the mounting screws (A,
Figure 73
)
and lower the oil level switch cover (B) from the
crankcase.
4. Pull the oil level switch (
Figure 74
) from the
crankcase.
154
CHAPTER FIVE
72
73
74
75