Checking The Piston Pin - Yamaha YJ50RAP Service Manual

CYLINDER HEAD, CYLINDER AND PISTON
Piston ring side clearance
Top ring
0.03 ~ 0.05 mm
(0.0012 ~ 0.0020 in)
<Limit>: 0.10 mm (0.0039 in)
2nd ring
0.03 ~ 0.05 mm
(0.0012 ~ 0.0020 in)
<Limit>: 0.10 mm (0.0039 in)
2. Install:
• piston ring (into the cylinder)
NOTE:
@
Level the piston ring in the cylinder with the
piston crown.
a 10 mm (0.39 in)
3. Measure:
• piston ring end gap
Out of specification → Replace the piston
ring.
NOTE:
@
The oil ring expander spacer's end gap cannot
be measured. If the oil ring rail's gap is exces-
sive, replace all three piston rings.
Piston ring end gap
Top ring
0.15 ~ 0.35 mm (0.006 ~ 0.014 in)
<Limit>: 0.70 mm (0.028 in)
2nd ring
0.15 ~ 0.35 mm (0.006 ~ 0.014 in)
<Limit>: 0.70 mm (0.028 in)
EAS00265

CHECKING THE PISTON PIN

1. Check:
• piston pin
Blue discoloration/grooves → Replace the
piston pin and then check the lubrication
system.
5 - 9
ENG