Yamaha 25BMH 30HMH Factory Service Manual, Page 250Get this manual
CRANKSHAFT AND CYLINDER BODY
3Measure: Piston diameter (use an outside micrometer) Out of specification ReplaceOutside micrometer 90890-03008 Measuring point "H"
Standard nda
Piston diameter 71.94 71.96 mm (2.8323 2.8331 in)
10.0 mm (0.3937 in)
ver di Over size piston diameter: 844 1: 72.25 mm (2.8445 in) 7272854 2: 72.50 mm (2.8543 in)