2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 190Get this manual
ENGINE REMOVALINSTALLATION Turn the rear axle bearing holder to obtain maximum drive chain slack (page 4-22)Remove the bolt, washer and drive sprocket from the countershaftRemove the drive sprocket from the drive chain
DRIVE SPROCKET Remove the crankcase breather hose clamp('04 '05 model only) Remove the upper engine hanger nut, bolt, two collarsRemove the engine hanger plate bolts and hanger platesLATE BOLTS CLAMP