2006-2012 Honda TRX90 TRX90EX/X Service Manual, Page 117Get this manual
CYLINDER HEADVALVES Install the dowel pinInstall the cam chain on the cam sprocketInstall the cam sprocket aligning its "0mark with the index notch on the cylinder head
Install and tighten the cam sprocket bolts to the specified torque TORQUE: N'm (0.9 kgfm6.5 IbUt)