A status report:

Sunday, I removed the carb and did a few things. I put the fuel line around the needles as is suggested for fuel leaks on Flitelinesolutions.com, and I also removed screws (cam screw and barrel stop screw) and put a touch of sealant in the threads. I removed the two screws that hold the high speed needle ass'y to the side of the carb and sealed that, tightening the screws, as well.

I put a little sealant on both top and bottom of the gasket that goes between the carb and crankcase, and pressed the carb down as tightly as possible while tightening the set screw on the side (I put a little sealant on those threads, too).

Monday, I fired it up and fussed with the needles to get the performance back to what it had been before my disassembly. I also swapped my throttle linkage to the inner hole on the carb arm and used my travel adjustments on the transmitter to reconfirm that I'm getting full WOT and completely closed with the throttle cut switch. I set my closed throttle position on the transmitter to one click of sub trim above load on the servo.

Just a few minutes ago, Tuesday, I ran it again. I set my idle trim to 10 clicks up from closed throttle. FWIW, prop is TF PP maple 9-4. WOT tachs at 13,500 RPM and when I pull the stick to idle, it comes to about 5,000, then slowly drops over the next 30 seconds to 4, 000 and eventually evens out around 3,500. Anytime it will rev right back up without hesitation or bogging.

If I hit the throttle cut and hold it, or, accomplishing the same thing, pull the throttle trim back to zero, the idle drops a bit more, to around 3,000 RPM. I can kill it easily by putting my finger over the exhaust outlet (I'm using a 1/2" ID silicone extrension, the large Dubro one to direct the gunk away from the bottom of the plane, so no risk of burns).

What I'm thinking is that the throttle barrel is too loose (too much clearance built in by the machining tolerances) in the carb. I think the idea of an air leak at the front bearing and crankshaft (which was also suggested by the guys at flitelinesolutions) begs the question, "Where is the fuel coming from?"

I dont think I'll be able to fix this problem without replacing the carb. Right now I'd be happy if I could get it to idle at 3,500 RPM immediately after pulling the throttle down, rather than having to wait for it to slow down when it feels like it. I think I also have another problem mentioned on Flitelinesolutions.com, that is that the throttle cam screw is worn just a bit and the throttle barrel will float side-to-side, varying the idle mixture willy-nilly. But, their idea of inserting a piece of a ballpoint pen spring to hold the throttle biased to one side is problematic with my engine because the spring keeps the throttle barrel from fully closing, which would kick my idle up to about 8,000 RPM!

Anyway, sorry for the long post, and thanks for your suggestions. I'm still open to try a few things before I give up. I may just fly it like it is, though.

Phil

Edit: PS: Fuel is Omega 10%, castor/synthetic blend. Ran it again after writing the above, and three clicks richer on low end needle let the speed come down to idle a little quicker, still with a good transition.