Yamaha XF50W - Checking the Piston Rings

CYLINDER AND PISTON
EAS00263
CHECKING THE PISTON RINGS
1. Measure:
• piston ring side clearance
Out of specification -» Replace the pis-
ton and piston rings as a set.
NOTE:
Before measuring the piston ring side clearance,
eliminate any carbon deposits from the piston
ring grooves and piston rings.
Piston ring side clearance
Top ring
0.03 ~ 0.07 mm(0.0012~0.0028 in)
<Limit>: 0.12mm(0.0047 in)
2nd ring
0.02 ~ 0.06 mm(0.0008~0.0024 in)
<Limit>:0.12 mm(0.0047 in)
2. Install:
8piston ring
(into the cylinder)
NOTE:
Level the piston ring into the cylinder with the
piston crown.
a 10 mm (0.3937 in)
3. Measure:
• piston ring end gap
Out of specification -» Replace the pis-
ton 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
0.05 ~ 0.15 mm (0.0020 ~ 0.0059 in)
<Limit>: 0.40 mm (0.0157 in)
2nd ring
0.05 ~ 0.17 mm (0.0020 ~ 0.0067 in)
<Limit>: 0.52 mm (0.0205 in)
Oil ring
0.20 ~ 0.70 mm (0.0079 ~ 0.0276 in)
5-35
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