Yamaha TTR125LM, Owner'S Service Manual

Page: 256 / 468

4 - 36
ENG
CYLINDER AND PISTON
Piston ring
1. Measure:
●
Ring side clearance
Use a feeler gauge.
Out of specification
→
Replace the pis-
ton and rings as a set.
NOTE:
Clean carbon from the piston ring grooves and
rings before measuring the side clearance.
Side clearance:
Standard <Limit>
Top
ring
0.035 ~ 0.090 mm
(0.0014 ~ 0.0035 in)
0.12 mm
(0.0047 in)
2nd
ring
0.020 ~ 0.060 mm
(0.0008 ~ 0.0024 in)
0.12 mm
(0.0047 in)
2. Position:
●
Piston ring
(in cylinder)
NOTE:
Insert a ring into the cylinder and push it
approximately 40 mm (1.57 in) into the cylin-
der. Push the ring with the piston crown so that
the ring will be at a right angle to the cylinder
bore.
a
40 mm (1.57 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.
End gap:
Standard <Limit>
Top
ring
0.15 ~ 0.30 mm
(0.006 ~ 0.012 in)
0.4 mm
(0.016 in)
2nd
ring
0.30 ~ 0.45 mm
(0.012 ~ 0.018 in)
0.55 mm
(0.022 in)
Oil ring
0.20 ~ 0.70 mm
(0.01 ~ 0.03 in)
—