Yamaha TT-R125EY Service Manual page 129

CYLINDER AND PISTON
Piston ring
1. Measure:
• Ring side clearance
Use a feeler gauge.
Out of specification → Replace the piston
and rings as a set.
TIP
Clean carbon from the piston ring grooves and
rings before measuring the side clearance.
Top
Ring (0.0014 ~ 0.0035 in)
2nd
Ring (0.0008 ~ 0.0024 in)
2. Position:
• Piston ring
(in cylinder)
TIP
Insert a ring into the cylinder and push it
approximately 40 mm (1.57 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 40 mm (1.57 in)
3. Measure:
• Ring end gap
Out of specification → Replace.
TIP
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
2nd
Ring
Oil ring
4-36
ENG
Side clearance:
Standard <Limit>
0.035 ~ 0.090 mm 0.12 mm
(0.0047 in)
0.020 ~ 0.060 mm 0.12 mm
(0.0047 in)
End gap:
Standard <Limit>
0.15 ~ 0.30 mm
(0.006 ~ 0.012 in) (0.016 in)
0.15 ~ 030. mm
(0.012 ~ 0.018 in) (0.016 in)
0.20 ~ 0.70 mm
(0.01 ~ 0.03 in)
0.4 mm
0.4 mm
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