2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 302Get this manual
CRANKCASETRANSMISSIONCRANKSHAFTBALANCER ('04'05) Install the primary drive gear onto the crankshaft by aligning the wide groove with the flat tooth (punch mark)
Temporarily install the clutch outer guide, needle bearing and clutch outer onto the mainshaftApply oil to the primary drive gear bolt threads and seating surface, and install the washer and boltInstall the special tool between the primary drive and driven gears as shown, and tighten the primary drive gear boltTOOL: Gear holder, M2.5 07724-0010100 or 07724-001A100 (U.S.Aonly)