Installing The Piston - Yamaha YFM50S Service Manual

120˚
e a
120˚ 120˚
f f
b
d
c
1
3
New
2
CYLINDER AND PISTON
EBS00252

INSTALLING THE PISTON

1. Install:
• piston rings
(onto the piston)
NOTE:
_
• Be sure to install the piston rings so that the
manufacturer's
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.
a Top ring end
b Upper oil ring rail end
c Expander end
d Lower oil ring rail end
e 2nd ring end
f 20 mm (0.79 in)
3. Install:
• piston 1
• piston pin 2
• piston pin clips 3
NOTE:
_
• Apply engine oil onto the piston pin, piston
rings and piston.
• Be sure that the arrow mark a on the piston
points to the exhaust 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
NOTE:
_
Apply a liberal coating of engine oil.
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ENG
marks or numbers
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are