BOMBARDIER Johnson 90 Service Manual page 203

POWER UNIT
CYLINDER / CRANKSHAFT / PISTON
PISTON
lnspect piston for faults, cracks or other damage. Replace if
necessary.
Piston ring to groove clearance
Before checking, piston grooves should be clean, dry and
free of carbon. Fit piston ring into piston groove, and mea­
sure clearance between ring and ring groove using thickness
gauge.
Bm
Thlckness gauge
Plston ring to groove clearance:
Standard:
1st 0.030-0.070 mm (0.0012- 0.0028 in)
2nd 0.020 - 0.060 mm (0.0008 - 0.0024 in)
Servlce llmlt:
1 st 0.12 mm (0.005 in)
2nd 0.1 O mm (0.004 in)
lf measurement exceeds service limit, replace piston and/or
piston ring.
Piston ring groove width:
Standard:
1 st 1.22 - 1.24 mm (0.048 - 0.049 in)
2nd 1.51 -1.53 mm (0.059-0.060 in)
Oil 2.51 - 2.53 mm (0.099-0.100 in)
Plston rlng thickness:
Standard:
1st 1.17-1.19 mm (0.046-0.047 In)
2nd 1.47-1.49 mm (0.058- 0.059 in)
Piston ring
6-49