Suzuki DF 90 Service Manual page 191

6-46 POWER UNIT
PISTON
Inspect 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 measure clearance be-
tween ring and ring groove using thickness gauge.
09900-20803 : Thickness gauge
Piston ring to groove clearance :
Standard :
1 st 0.030 – 0.070 mm (0.0012 – 0.0028 in.)
2 nd 0.020 – 0.060 mm (0.0008 – 0.0024 in.)
Service limit :
1 st 0.120 mm (0.0047 in.)
2 nd 0.100 mm (0.0039 in.)
If 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.)
2 nd 1.51 – 1.53 mm (0.059 – 0.060 in.)
Oil 2.51 – 2.53 mm (0.099 – 0.100 in.)
Piston ring thickness :
Standard :
1 st 1.17 – 1.19 mm (0.046 – 0.047 in.)
2 nd 1.47 – 1.49 mm (0.058 – 0.059 in.)
Piston ring