Disassembling The Cylinder Block; Checking The Piston Diameter - Yamaha F90D Service Manual

Disassembling the cylinder block

1. Place a rag under the oil filter, and then
remove the filter using the oil filter
wrench.
NOTE:
Be sure to clean up any oil spills.
Oil filter wrench: YU-38411
2. Remove the crankcase bolts in the
sequence shown, and then remove the
crankcase.
NOTE:
Do not remove the ignition timing pointer
from the crankcase.
3. Remove the connecting rod bolts and the
connecting rod caps, and then remove
the crankshaft, oil seals, and the piston
assemblies.
6D81G11
NOTE:
• Be sure to keep the bearings in the order as
they were removed.
• Mark each piston with an identification
number a of the corresponding cylinder.
• Do not mix the connecting rods and caps.
Keep them organized in their proper
groups.

Checking the piston diameter

1. Measure the piston outside diameter at
the specified measuring point. Replace if
out of specification.
S6D85560
Cylinder block
Piston diameter a:
78.928–78.949 mm
(3.1074–3.1082 in)
Measuring point b:
13.0 mm (0.51 in) up from the
bottom of the piston skirt
Oversize piston diameter:
79.178–79.199 mm
(3.1172–3.1181 in)
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