Yamaha 40V - Piston Ring Inspection

5-35
POWR
E
CRANK SHAFT AND PISTON
Piston ring inspection
1. Inspect:
● Piston ring
Breakage/Damage → Replace.
2. Measure:
● End gap
Use a feeler gauge.
Out of specification → Replace.
NOTE:
Install the piston ring into the cylinder. Push
the ring with the piston crown.
End gap:
Top: 0.40 ~ 0.60 mm
(0.016 ~ 0.024 in)
2nd: 0.40 ~ 0.60 mm
(0.016 ~ 0.024 in)
End gap limit:
Top: 0.80 mm (0.031 in)
2nd: 0.80 mm (0.031 in)
Measuring point
20 mm (0.8 in)
3. Measure:
● Side clearance
Use a thickness gauge.
Out of specification → Replace piston
and/or ring.
Side clearance:
Top: 0.04 ~ 0.08 mm
(0.002 ~ 0.003 in)
2nd: 0.03 ~ 0.07 mm
(0.001 ~ 0.003 in)