Yamaha Marine Outboards Factory Service / Repair/ Workshop Manual 225G 250B L250B, Page 138Get this manual
CYLINDER BODY ASSEMBLY
2Measure: Piston ring side clearance (with thickness gauge) Out of specification Replace the piston and piston rings as setPiston ring side clearance 0.020.06 mm (0.0010.002 in) NOTE: When measuring the piston ring side clearance, the outside of the piston ring should be flush with the piston wall
INSPECTING THE OIL PUMP DRIVEN GEAR 5
Inspect: Oil pump driven gear Crackspittingwear Replace