2006-2012 Honda TRX90 TRX90EX/X Service Manual, Page 181Get this manual
CRANKCASEITRANSMISSIONCRANKSHAFT SHIFT DRUM
Inspect the shift drum grooves for wear or damageMeasure the O.Dof the shift drumSERVICE UMIT: 33.93 mm (1.336 in)
SHIFT FORK
Measure the shift fork I.DSERVICE UMIT: 34.14 mm (1.344 in)
Measure the shift fork claw thicknessSERVICE UMIT: 4.60 mm (0.181 in)