Motorcycle Repair: oil blowing out holes for carb air intake, hollow bolts, bolt holes

Question
Mike, I have a 1996 Electra Glide Classic. On a trip out west I blew a hole in the rear piston. I have since rebuilt it twice. The problem is oil keeps being blown out the hole where the air is sucked in through the caburetor. There is a hollow screw that holes the carburetor backing plate to the head of the engine, which I understand lets cold air in but is not supposed to let oil back threw that bolt because of a butterfly valve that is supposed to prevent this. Like I said I have rebuilt it twice, with all new gaskets but the oil still is being forced out of the bolt holes. I don't know what to do. I have talked to Harley techs but all they said is either a bad butterfly valve to the rings are seating. Help!

Answer
the hollow bolts you are talking about is where the heads are vented. Air comes out not in.  Since there is oil in the heads a small amount of oil usually goes with it. When you did the pistons did you bore the cylinders with pressure plates on them? Are you getting smoke out the exhaust?
Mike