Yamaha Marine Outboards Factory Service / Repair/ Workshop Manual 225G 250B L250B, Page 136Get this manual
CYLINDER BODY ASSEMBLY
Oversize piston diameter 1st oversize 90.15 mm (3.549 in) 2nd oversize 90.40 mm (3.559 in) : Except for USA
NOTE: When measuring the piston diameter, position the micrometer in relation to the piston pin hole as shown
CALCULATING THE PISTON-TOCYLINDER CLEARANCE
Calculate: Piston-to-cylinder clearance Out of specification Replace the piston and piston rings, the cylinder or both5450