The Perry Carb solved the backflow problem on the K&B, although the carb started to leak above 3/4 throttle. That is a hole different story though; Conely is helping me figure this one out. At the recommendation of a friend, I took the O.S. .40 apart, and soaked it in carb cleaner. He said that dirt or buildup of castor will cause the passage ways to stay open, when the carb is closed. This will allow the fuel to be drawn back into the tank at idle. I was very skeptacle, but did as I was told. I did not place any parts with o-rings in the carb cleaner, as this would swell the o-rings. I just wiped these parts off with a rag soaked in Marvel Mystery oil. Before re-assembling, I blew all passageways out with compressed air. I was a skeptic, but it worked. We put over an hour of flying time on that engine, last night, and it performed great! The kid I fixed it for was really happy! I also broke in a new GMS .47 for him. It was a very, very nice performing engine. I mounted it on my SE, by the way, with the uniflo tank. Very sweet combo!

Andy