Checking The Piston Rings - Yamaha XT660R Service Manual

CYLINDER AND PISTON
EAS00263

CHECKING THE PISTON RINGS

1. Measure:
• piston ring side clearance
Out of specification → Replace the piston
and piston rings as a set.
NOTE:
_
Before measuring the piston ring side clear-
ance, eliminate any carbon deposits from the
piston ring grooves and piston rings.
Piston ring side clearance
2. Install:
• piston ring
(into the cylinder)
NOTE:
_
Level the piston ring into the cylinder with the
piston crown.
a 40 mm (1.57 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
5 - 36
ENG
Top ring
0.030 ~ 0.080 mm
(0.0012 ~ 0.0031 in)
<Limit>: 0.13 mm (0.0051 in)
2nd ring
0.030 ~ 0.070 mm
(0.0012 ~ 0.0028 in)
<Limit>: 0.11 mm (0.0043 in)
Top ring
0.20 ~ 0.35 mm
(0.0079 ~ 0.0138 in)
<Limit>: 0.60 mm (0.0236 in)
2nd ring
0.35 ~ 0.50 mm
(0.0138 ~ 0.0197 in)
<Limit>: 0.85 mm (0.0335 in)
Oil ring
0.20 ~ 0.70 mm
(0.0079 ~ 0.0276 in)