Checking The Piston Rings - Yamaha YFM250RX 2008 Service Manual

CYLINDER AND PISTON
Piston-to-cylinder clearance
0.010 ~ 0.025 mm
(0.0004 ~ 0.0010 in)
Limit
0.15 mm (0.006 in)
f. If out of specification, rebore or replace the
cylinder, and replace the piston and piston
rings as a set.

CHECKING THE PISTON RINGS

1. Measure:
• Piston ring side clearance
Out of specification → Replace the piston
and piston rings as a set.
NOTE: NOTE:
Before measuring the piston ring side clear-
ance, eliminate any carbon deposits from the
piston ring grooves and piston rings.
Piston ring
Top ring
Ring side clearance
0.030 ~ 0.065 mm
(0.0012 ~ 0.0026 in)
Limit
0.115 mm (0.0045 in)
2nd ring
Ring side clearance
0.020 ~ 0.055 mm
(0.0008 ~ 0.0022 in)
Limit
0.115 mm (0.0045 in)
4-34
ENG