2007-2009 Honda TRX300EX TRX300X service manual, Page 216Get this manual
CRANKCASETRANSMISSIONCRANKSHAFT Remove the mainshaft bearing using the special toolsTOOLS:
Bearing remover, 17 mm Remover handle Remover weight
07936-3710300 07936-3710100 07741-0010201 or 07936-371020A or 07936-3710200 (U.S.Aonly)
Apply engine oil to each bearingDrive new mainshaft, countershaft, balancer and shift drum bearings with the markings facing up, using the special toolsTOOLS:
Balancer bearing: Driver Attachment, 37 40 Pilot, 17 mm Mainshaft bearing: Driver Attachment, 37 40 Pilot, 17 mm Countershaft bearing: Driver Attachment, 52 55 Pilot, 22 mm Shift drum bearing: Driver Attachment, 42 47 Pilot, 25 mm