2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 334Get this manual
CRANKCASETRANSMISSIONCRANKSHAFTBALANCER (After '05) COUNTERSHAFT C1 GEAR (29T) THRUST WASHER C5 GEAR (26T) SNAP RING SPLINE WASHER C3 GEAR (23T) C3 BUSHING THRUST WASHER THRUST WASHER
THRUST WASHER C2 BUSHING
THRUST WASHER C2 GEAR (25T)
Apply molybdenum oil solution to the sliding surfaces of the transmission gearsAssemble the mainshaft and countershaftNOTE: Always install the washer and snap ring with the chamfered (rolled) edge facing away from the thrust load Do not reuse worn snap ring which could easily spin in the groove Install the snap ring so that its end gap aligns with the groove in the splines Make sure that the snap ring is fully seated in the shaft groove after installing itInstall the mainshaft and countershaft as an assembly into the left crankcase