Yamaha Outboard Motors Factory Service Manual F6 and F8, Page 290Get this manual
CRANKSHAFT, PISTON AND CYLINDER BODY NOTE:
When measuring the piston diameter, position the micrometer in relation to the piston pin hole as shown2Measure: Piston pin boss inside diameter (with micrometer) Out of specification Replace the pistonPiston pin boss inside diameter: 14.00414.015 mm (0.55130.5518 in)
CALCULATING THE PISTON-TOCYLINDER CLEARANCE
Calculate: Piston-to-cylinder clearance Out of specification Replace the piston and piston rings, the cylinder or both= Cylinder bore diameter Piston diameter