1994-1995 Yamaha FX700 (FX1) Service Manual, Page 75Get this manual
REED VALVE, CYLINDER HEAD, CYLINDER AND PISTON 2Inspect: Piston wall Score or replaceUse #600-800 grit wet sandpaper
Sand in crisscross patternDo not sand excessively
3Measure: Piston skirt diameter Use micrometerOut of
Piston diameter 80.925-80.950 mm (3.186-3.187 in)
4Calculate: Piston clearance Out of as set
Distance 10mm (0.39 in)