lets do this, pull the rocker box off so you can see the rockers. now remove the pull starter cover so you can get at the starter cage. behind the starter cage, near the top of the cover case, is an arrow/index mark. remove the spark plug, remove the sight hole cap from the right back side so you can see the timing mark on the flywheel. with a 17mm socket, line up the timing mark on the flywheel in the sight hole, piston should be on top dead center, turn the crank with the 17mm socket counter clockwise, watch the intake valve, does it start to move any at all when you do this ?, if not ?, turn the crank clockwise one full turn to line the timing mark up in the sight hole, also look to see where the line/punch mark is on the starter cage ?, it should be facing the arrow/index mark stamped right at/behind the starter cage on the cover @ about 11:00 o'clock if I remember right ?. you have two timing marks your lining up, one is the sight hole on the flywheel, the other is the starter cage that has that line stamped on the cage, and it lines up with the arrow stamped on the cover right where I said, about 11:00 o'clock ?. these all line up. the trick here is getting them to line up, intake rocker moving when you turn it like I said above ^^^. if the intake rocker moves when doing this ?, put it back where you started, then check your valve adjustments. once all is set ?, your valves are done. if you still have this noise ?, then either your cam chain is stretched ?, or you have other issues going on. was the cylinder checked for piston to cylinder clearance ?, was the rod checked for any play at the top and bottom ?, wrist pin checked for play ?. my money says if all these are good ?, then your cam chain is the problem.
