I have a yfz450 that is cranking over hard. It appears that it makes a revolution and stops, the goes around again, over and over. The battery is new and fresh. I don't think it is the starter, but haven't totally ruled it out. The timing is spot on, and the valve lash appears to be fine. The one peculiar thing is that the decompression ball is not firm on the cam. I can push the ball about half way back in to the cam before it stops, with a small screwdriver, while holding the decomp arm down. If I slowly rotate the engine it does not appear that the cam is depressing the valve at all, but that may be so slight that I cant detect it. I guess the main question is, should the decomp ball be firmly all they way out at all times until the arm pulls away and allows the ball to rest inside the cam? Would doing the cam mod help with hard starting at all?