Re: well i messed up big time
A helicoil didnt work? Thats a new one on me, I've been useing them for years on full sized motorcycle engines with no problems, but ok, no biggie.
There are 2 options as i see it-
#1- drill and tap it out to the next larger size CAREFULLY!
#2- remove the cylinder, have the hole welded up and then drilled and re tapped for new studs.
If you choose to go the next over sized route be careful not to drill to deep or at a bad angle it might breech the exhaust port or the cylinder its self or even crack the barrel altogether.
At this point? id say screw it and buy a new cylinder, piston and rings from a reputeable dealer.
But thats me.