2006-2009 Honda TRX250EX/TRX250X Service Manual, Page 222Get this manual
CRANKCASETRANSMISSIONCRANKSHAFT Coat new O-ring with engine oil and install it into the groove in the countershaft protector
Install the protector and tighten the two boltsInstall the fOllowing:reverse stopper shaft (page 10-29) gearshift linkage (page 10-26) flywheel (page 11' 0) oil pump (page 5-7 camshaft (page 8-25) clutch (page 10-22) cylinder and piston (page 9-7) cylinder head (page B-20) engine (page 7-7)