Yamaha YFM90RA Model Vehicle User Manual


 
120˚
120˚ 120˚
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ENG
CYLINDER AND PISTON
EBS00252
INSTALLING THE PISTON
1. Install:
piston rings
(onto the piston)
TIP
Be sure to install the piston rings so that the
manufacturer’s marks or numbers are
located on the upper side of the rings.
Lubricate the piston and piston rings liberally
with engine oil.
2. Position:
top ring
2nd ring
oil ring
Offset the piston ring end gaps as shown.
top ring end
upper oil ring rail end
expander end
lower oil ring rail end
2nd ring end
20 mm (0.79 in)
3. Install:
piston
piston pin
piston pin clips
TIP
Apply engine oil onto the piston pin, piston
rings and piston.
Be sure that the “ IN ” mark on the piston
points to the intake side of the engine.
Before installing the piston pin clips, cover
the crankcase with a clean rag to prevent the
piston pin clips from falling into the crank-
case.
4. Lubricate:
piston
piston rings
cylinder
TIP
Apply a liberal coating of engine oil.
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