2005-2006 Honda ATV TRX500FE/FM/TM FourTrax Foreman Factory Service Manual, Page 157Get this manual
CYLINDERPISTON Check the top of the cylinder for warpage with straight edge and feeler gauge across the studs and bolt holes as shownSERVICE LIMIT: 0.10 mm (0.004 in)
PISTONPISTON RING
Inspect the piston rings for smooth movement by rotating themThe rings should be able to move in their grooves without catchingPush the ring until the outer surface of the piston ring is nearly flush with the piston and measure the ring-to-ring groove clearanceSERVICE LIMIT: TopSecond: 0.09 mm (0.004 in)