1997 Yamaha YFM600FWAK ATV Service Manual, Page 137Get this manual
CYLINDER AND PISTON
Measure cylinder bore "e" in parallel to and at right angles to the cylinder matching surfaceThen, find the average of the measurementsStandard Cylinder bore "C" 94.97 95.02 mm (3.739 3.741 in) C= X+Y elf out of specification, rebore or replace the cylinder, and replace the piston and piston rings as set2nd step Measure piston skirt diameter "p" with micrometer() 5.0 mm (0.20 in) from the piston bottom edge
Wear limit 95.1 mm (3.744 in)