2007-2009 Yamaha F15/F20 Outboard Service Manual, Page 143Get this manual
Power unit
Checking the piston ring end gap
1Level the piston ring in the cylinder with piston crown2Measure the piston ring end gap at the specified measuring point b
Piston ring groove: Top ring a: 1.211.23 mm (0.04760.0484 in) 2nd ring b: 1.211.23 mm (0.04760.0484 in) Oil ring c: 2.512.53 mm (0.09880.0996 in)
S6AG5860
Checking the piston ring side clearance