Changing cylinder Gasket.?

Like the two other guys stated, check to make sure that the cylinder and the case where the cylinder mounts to isn't warped. Also, your head gasket may not be the only problem; it could be that your cylinder has a crack in the sleeve, or the head bolts got overtorqued, which would ruin the gasket. First off, you need to find another mechanic to take your bike to, the mechanic you used before obviously is a dope. Have all of the above-mentioned items checked, and also the cylinder head as well. Replace the head and cylinder hardware when you go to put it all back together. When the top end does go back together, the bolts need to be torqued properly and in the proper sequence. Good luck.