2006 Arctic Cat Y-6/Y-12 50cc and 90cc Service Manual, Page 49Get this manual
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27Install the chain over the camshaft sprocketThe larger hole should be directed away from the head and the timing marks should be parallel to the cylinder head top surface
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29Install the two alignment pins and the camshaft holder onto the cylinder headUsing common screwdriver turn the rocker arm shafts to locate the recess to the studs
28Install the rocker arm assembly into the camshaft holderNOTE: To enable installation on the head studs, the recesses in the rocker arm shafts must be aligned with the holes in the shaft supports