Got Adam's bike buttoned up and fired but there was a tic in the engine. Re-checked valve clearances but I knew it wasn't that. Took the head off and 2 carb choke plate screws where imbedded in the head of the #3 & #4 cylinder. Got lucky as the valve seats, cyl. walls and pistons were salvageable after some "de-burring"!!! Cut some new seats, put in some reconditioned valves in, lapped the valves in the fresh seats, honed the cylinders, and put it back together using new gaskets.