I've got a quick question about a Walbro HDC carb off an XL chainsaw. I converted the engine and put it in a Four Star 120, and have 4 days of flying with it now. The first two sessions went great, but the 3rd time out, on the second flight the engine started to lean out in the air. I landed, and flew my other plane for the rest of that day. Later, I took the carb off and checked the screen, and it did have a bit of trash in there which I cleaned real well. I took the rest other side of the carb apart as well, and checked under the diaphragm for a second screen, which this carb doesn't have. Everything looked good so I put it back together, then took the plane out for some more flying. I dialed the low and high speed needles in, and had it running great. About 10 minutes into the flight it started to lean out again in the top end. I landed and checked the needle, which hadn't moved. I opened it a little and it was running great again for a few more minutes, then started to lean out again. I checked the screen again, and there's no trash in it now.

Do any of you have any ideas on what could be making the carb lean out like this? I think I'll just order a kit and rebuild it, unless there's some other simple fix. Everything looks ok though, I don't know what could be causing it. It's just in the top end though. The bottom end always stays perfect, with a great idle. Even when it starts bogging out at the top, I can fly it back on 1/2 throttle to land it just fine.