Checking The Piston Ring - Yamaha YFM660FP Service Manual

CYLINDER AND PISTON

CHECKING THE PISTON RING

1.Measure:
Ring side clearance
●
Use a feeler gauge.
Out of specification → Replace the piston
and rings as a set.
NOTE:
Clean carbon from the piston ring grooves and
rings before measuring the side clearance.
Top
ring (0.0016 ~ 0.0031 in)
2nd
ring
(0.0012 ~ 0.0028 in)
2.Position:
Piston ring
●
(in cylinder)
NOTE:
Insert a ring into the cylinder and push it
approximately 50 mm (2.0 in) into the cylinder.
Push the ring with the piston crown so that the
ring will be at a right angle to the cylinder bore.
a 50 mm (2.0 in)
3.Measure:
Ring end gap
●
Out of specification → Replace.
NOTE:
You cannot measure the end gap on the
expander spacer of the oil control ring. If the oil
control ring rails show excessive gap, replace
all three rings.
Top
ring
(0.0118 ~ 0.0177 in)
2nd
ring
(0.0118 ~ 0.0177 in)
Oil
ring
(0.0079 ~ 0.0276 in)
4 - 35
ENG
Side clearance
Standard
0.04 ~ 0.08 mm 0.13 mm
(0.0051 in)
0.03 ~ 0.07 mm 0.13 mm
(0.0051 in)
End gap
Standard
0.30 ~ 0.45 mm 0.70 mm
(0.0276 in)
0.30 ~ 0.45 mm 0.80 mm
(0.0315 in)
0.2 ~ 0.7 mm
Limit
Limit
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