Checking The Piston Pin - Yamaha YFZ450S 2003 Service Manual

CYLINDER AND PISTON
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
EBS00251

CHECKING THE PISTON PIN

1. Check:
• piston pin
Blue discoloration/grooves → Replace the
piston pin and then check the lubrication
system.
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ENG
Top ring
0.20 ~ 0.30 mm
(0.008 ~ 0.012 in)
<Limit>: 0.55 mm (0.022 in)
2nd ring
0.35 ~ 0.50 mm
(0.014 ~ 0.020 in)
<Limit>: 0.85 mm (0.034 in)
Oil ring
0.20 ~ 0.50 mm
(0.008 ~ 0.020 in)