If your talking about getting the head re-cut from a piston failure go see Tom at Mott's Machining is St Albert, he the best IMO and he's a site sponsor. While your there you may's well get you cylinder honed or bored depending on damage too, he can supply all parts pistons, clips etc. Tom did all the machining on my CR 250, you can seee the pics in a thread re-birth of cr250, now the slow break-in process:d