2006-2009 Honda TRX250EX/TRX250X Service Manual, Page 156Get this manual
CYLINDERPISTON Place clean shop towel over the crankcase to prevent the piston pin clip from falling into the crank-
caseApply engine oil to the connecting rod small end inner surface
Apply engine oil to the piston pin holes and piston pin outer surface
Set the piston over the connecting rod with the "IN "
mark facing toward the intake side and insert the piston pin through the piston and connecting rod
Do not allQn the clip Install new piston pin clips into the grooves in the end f18P WIth the piston pin hotePISton cutout