Yamaha TT-R50E Owner's Service Manual page 238

CYLINDER AND PISTON
Piston ring
1. Measure:
• Ring side clearance
Use a thickness gauge.
Out of specification → Replace the piston
and rings as a set.
Thickness gauge:
YM-34483/90890-03079
NOTE:
Clean carbon from the piston ring grooves and
rings before measuring the side clearance.
Top ring
2nd ring
2. Position:
• Piston ring
(in cylinder)
NOTE:
Insert a ring into the cylinder and push it
approximately 10 ~ 15 mm (0.39 ~ 0.59 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 10 ~ 15 mm (0.39 ~ 0.59 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
2nd ring
Oil ring
4 - 26
ENG
Side clearance
Standard
0.020 ~ 0.070 mm
(0.0008 ~ 0.0028 in)
0.020 ~ 0.060 mm
(0.0008 ~ 0.0024 in)
End gap
Standard
0.10 ~ 0.25 mm
(0.004 ~ 0.010 in)
0.15 ~ 0.30 mm
(0.006 ~ 0.012 in)
0.20 ~ 0.70 mm
(0.008 ~ 0.028 in)
Limit
0.12 mm
(0.005 in)
0.12 mm
(0.005 in)
Limit
0.50 mm
(0.020 in)
0.65 mm
(0.026 in)
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