Still looking for the right answer about my 2000 Kawasaki prairie Timing?

[dmnnk]

I started with a broken cam chain dowel pin on the sprocket, bent valves, stretched timing chain. Replaced with new parts, set everything by the manual,got it running but would pop back through the carb if you open up the throttle but would idle perfect high or low idle, but after running for a few minuets would get very hot so I checked my timing and it just will not line up with the timing marks exact that the manual says. Could the timing chain sprocket on the crankshaft move from its original position, or am I missing something that is not covered in the manual. I would like the right advice, as I also answer questions a lot on answers dealing with Small engine repair but this is a whole different problem than repair on a lawnmower which does not have any timing chain or sprockets to deal with