I just bought a 2002 400ex. The guy said he bored it one over, spent $600 on a top end rebuild and now it won't start. It will only sputter. I take it home and start looking at it. It seems to have good compression my compression gauge won't fit it. I look at the timing chain and put the motor at TDC. The cam has marks arent lining up. So I jump the timing chain one tooth on the cam gear. It still isnt quite lining up but it is a little closer. I put it back together and still will only sputter (little more consistant this time though) Do I need a new timing chain? Is it common for these chains to stretch? The timing marks on the cam gear are only off like 2mm. Should it still idle but rough? Any help will be greatly appreciated. Thanks!