go2 mopedwarehouse.com. and order 4 new cylinder head studs, they have them for the Maxi's engine, i dunno about others. i did the same thing on my Tomos, and just replaced the studs. once you have the piston/cylinder off put vise grips on the ends of the old studs and unscrew them, they unscrew from the crankcase, then just screw the new studs in where the old ones came out of, and put 2 of the cylinder head nuts on the end of each and lock them 2gether and tighten the top nut to tighten down the studs (remove them after you tighten each stud of course!). i would think this would be a lot easier and more reliable than having the threads on the exsisting studs re tapped or helicoiled.