2007-2009 Yamaha F15/F20 Outboard Service Manual, Page 144Get this manual
Cylinder block
Checking the piston pin boss bore
1Measure the piston pin boss boreReplace the piston if out of specification
2Measure the connecting rod small end inside diameter and big end inside diameter bReplace the connecting rod if out of specification
S6AG5890 S6AG5H70
NOTE: When measuring the piston pin boss bore, do not measure it at the ring groove aPiston pin boss bore: 16.00416.015 mm (0.63010.6305 in)
Checking the piston pin diameter
Connecting rod small end inside diameter a: 16.01516.029 mm (0.63050.6311 in) Connecting rod big end inside diameter b: 34.03034.042 mm (1.33981.3402 in)