2008 Arctic Cat 400/500/650/700 ATV Service Manual, Page 123Get this manual
12With the alignment pin installed in the camshaft and the cam lobes directed down (toward the piston), place the camshaft in position and verify that the timing mark on the magneto is visible through the inspection plug and that the timing marks on the camshaft sprocket are parallel with the valve cover mating surfaceNOTE: When the camshaft assembly is seated, make sure the alignment pin in the camshaft aligns with the smallest hole in the sprocket MD1270
8Install the two lower nuts securing the cylinder head to the cylinder, one in front and one in rear
13With the alignment pin installed in the camshaft, loosely place the cam sprocket (with the recessed side facing the camshaft lobes) onto the camshaft and place it into position with the cam chain over the sprocket
9In crisscross pattern, tighten the four cylinder head cap screws (from step 7) to 27.5 ft-lbTighten the two lower cylinder head nuts (from step 8) to 18 ft-lb and the cylinder-to-crankcase nuts (from step 4) to ft-lb10With the timing inspection plug removed and the cam chain held tight, rotate the crankshaft until the piston is at top-dead-center11While holding the cam chain sprocket to the side, install the rear cam chain tensioner guide into the cylinder headInstall the pivot cap screw and washer