JDW: I've found that the idle setting is, as you say, very sensitive. But for my engine, getting the settings right was not possible. Prior to drilling out the fuel intake in the carb body, I had very little response to the high needle setting (as many others in this string have also stated). Without any modifications, I could get my 47 to run and transition on the ground perfectly. But it would die in the air EVERY [&o] time, sometimes on takeoff, sometimes on a climb - it just quits. After modifications, I can set the high speed needle (remote needle valve) with noticable change to engine performance. This allows me to get even closer on the low speed needle than I've been previously able. I'm also running the stock tuned muffler rather than the tower muffler as on your engine. Reaming out the nipple on the muffler creates just a little more tank pressure so that the engine can maintain fuel flow when the plane is vertical.