Yamaha CS50 - Checking the Piston Rings

ENG
INSPECTION AND REPAIR
4-14
EAS00263
CHECKING THE PISTON RINGS
1. Measure:
• piston ring side clearance
Out of specification

Replace the piston
and piston rings as a set.
Use a Feeler Gauge 
NOTE:
Before measuring the piston ring side clearan-
ce, eliminate any carbon deposits from the
piston ring grooves and piston rings.
2. Install:
• piston ring
(into the cylinder)
NOTE:
Level the piston ring into the cylinder with the
piston crown.
a 20 mm
3. Measure:
• piston ring end gap
Out of specification

Replace the piston
ring.
Use a Feeler Gauge 
Piston ring side clearance
Top ring
0.03 ~ 0.05 mm
<Limit>: 0.1 mm
2nd ring
0.03 ~ 0.05 mm
<Limit>: 0.1 mm
Piston ring end gap
Top ring
0.15 ~ 0.35 mm
<Limit>: 0.6 mm
2nd ring
0.15 ~ 0.35 mm
<Limit>: 0.6 mm