2003 Arctic Cat ATVs from 250cc to 500cc Service Manual, Page 113Get this manual
NOTE: When the camshaft assembly is seated, make sure the alignment pin in the camshaft aligns with the smallest hole in the sprocket CC375D
NOTE: At this point, oil the camshaft bearings, cam lobes, and the three seating journals on the cylinder
13With the alignment pin installed in the camshaft and the cam lobes directed down (toward the piston), place the camshaft in its seating position; then loop the chain over the sprocket and install the sprocket onto the camshaft
14When the camshaft assembly is seated, ensure the followingAPiston still at top-dead-center
BCamshaft lobes directed down (toward the piston)CCamshaft alignment marks parallel to the valve cover mating surface
DRecessed side of the sprocket directed toward the cam lobesECamshaft alignment pin and sprocket alignment hole (smallest) are aligned