2006-2014 Honda FourTrax ATV TRX250 EX TRX250X Service Manual, Page 148Get this manual
CYLINDERPISTON Check the top of the cylinder for warpage with straight edge and feeler gauge across he stud holesSERVICE LIMIT: 0.10 mm (0.004 in)
PISTONPISTON RING
Inspect the piston rings for smooth movem ent by rotating the themThe rings should be able to move in their grooves without catchingPush the ring until the outer surface of the pist on ring is nearly flush with the piston and measure the ring -to-ring groove clearanceSERVICE LIMIT: TopSecond: 0.09 mm (0.004 in)