I was taking my shims out because my valves needed adjusted, and when I took took out the 4 bolts that hold the cam assembly down(in criss cross pattern like stated in service manual) 2 of the 4 bolts snapped right about flush with the head. They snapped at the threads. So now I have half of the threads still In the cylinder head and 2 broken bolts. What do you guys recommend I do, yes I know they will have to be drilled out somehow, but any special tools or anything you know of? The bike ran fine before this happened though I thought it would run nicer if the valves were in spec.