Overtightened and torn 2 cyl head bolts. Please help!

[RedFoxCR]

Guys, i'm really sorry for not logging on for so long. My bad. I'm really grateful for every single bit of information you gave. Thaks a lot!!!

So, the situation is

I managed to screw out one bolt fragment drilling a small hole at the center of it and screwing there a special tool with right threads. However that didn't work out with the second one. I missed the center and made a hole half in bolt, half in cylinder meat. Screwing this shit out is just impossible, so i reassembled it with five bolts. O course the distribution of the force isn't very even and i have coolant slightly spraying outta head. However that doesn get into the bore cause the compression is still perfect.

MAybe it's possible to drill the whole bolt w ten millimetter drill (the bolt is 8mm diameter) and cut new big threads&

[eprovenzano]

At this point, I pull it off, and go to a machinist.  They have the tools and equipment to fix the problem.  Nothing like the right tool for the job.

[Cheb44]

I speak from experience please for the love of your engine block go to a machine shop, depending on how bad its screwed up it will only cost you about 30 bucks.

Btw as others have said make sure you use a torque wrench next time, head and cylinder bolts are probably the most important ones on your whole bike.