2006-2014 Honda FourTrax ATV TRX250 EX TRX250X Service Manual, Page 62Get this manual
MAINTENANCE Remove the timing hole cap from the left side of the rear crankcase cover
Turn the crankshaft counterclockwise and align theT" mark on the flywheel with the index mark on the rear crankcase coverMake sure the piston is at TOC on the compression stroke-If the piston is not at TOC, rotate the crankshaft 360 (1 full turn) and align the ''1'' mark with the index mark
Check the clearance of each valve by inserting feeler gauge between the adjusting screw and valve stem