2002 Yamaha YFM660 Grizzly factory service and repair manual, Page 178Get this manual
CYLINDER AND PISTON
CHECKING THE PISTON RING 1.Measure: Ring side clearance Use feeler gaugeOut of specification Replace the piston and rings as setNOTE: Clean carbon from the piston ring grooves and rings before measuring the side clearanceSide clearance Standard Top ring 2nd ring 0.040.08 mm (0.00160.0031 in) 0.030.07 mm (0.00120.0028 in) Limit 0.13 mm (0.0051 in) 0.13 mm (0.0051 in)