First off, yes, I'm talking about a two-stroke here, namely a CR250. It has been bored 2mm over, ported, and received a carb job. Problem is that I can't get rid of the pinging without race gas or octane boosters. Frankly, I'm no longer in the mood to pay extra $$$ to ride the bike. I'm tempted to try two head gaskets to see if reducing the compression will get rid of the pinging. I was thinking of either two standard thickness gaskets or one standard and one thinner high compression gaskets. I've looked for the thicker gaskets from Cometic been noone I've checked with carries them. Anyone have any working experience with an idea like this?