3-54 ENGINE PISTON AND PISTON RING PISTON DIAMETER • Using a micrometer, measure the piston outside diameter at 15 mm (0.6 in) A from the piston skirt end. • If the measurement is less than the limit, replace the piston. Piston diameter: Service Limit: 73.280 mm (2.8850 in) at 15 mm (0.6 in) from the skirt end 09900-20203: Micrometer (50 – 75 mm) PISTON-TO-CYLINDER CLEARANCE E • Subtract the piston diameter from the cylinder bore diameter. (3-53) L • If the piston-to-cylinder clearance exceeds the service limit, replace the crankcase set or the piston, or both. P Piston-to-cylinder clearance: M Service Limit: 0.120 mm (0.0047 in) A PISTON PIN AND PIN BORE S • Measure the piston pin bore diameter using the small bore gauge. • If the measurement is out of specification, replace the piston. Piston pin bore I.D.: Service Limit: 15.030 mm (0.5917 in) 09900-20602: Dial gauge (1/1000 mm) 09900-22401: Small bore gauge (10 – 18 mm) • Measure the piston pin outside diameter at three positions using the micrometer. • If any of the measurements is out of specification, replace the piston pin. Piston pin O.D.: Service Limit: 14.980 mm (0.5898 in) 09900-20205: Micrometer (0 – 25 mm)