I have an older 3W 100 in a 33% Edge. I built the plane around 7 years ago and had 40 or so flights on it and the engine, then other hobbies came and went and it sat in the house for 5 years. I used to run it on AvGas 100LL (due to the lack of smell), but when 9/11 came it became more difficult to buy AvGas so I ran it for the first time in 6 years on 93 octane. It ran fairly well, but had some coughs and burbles at times during the flight. I cut the 2 flights short because I didn't want to practice deadsticks.

Last night I started to adjust the carb to get this puppy running correctly. I went back to factory settings (1-1/2 L, 1 H; w/ a Tillotson carb). It ran ok, but the idle was somewhat rough, but the high end was strong. I first started to lean the low end down to 1-1/4 , but didn't seem to help the idle, so I started to richen the low end (screw it out) and the idle sped up and it smoothed out (ended up back at 1-1/2 turns open). However, now running it up to full throttle it would run fine until 3/4 throttle then would slow down and sometimes die. I then started to richen the high end, but all of a sudden couldn't get the engine to start. If I would choke the engine it would start and die (just like it should), then turn the choke off and couple of flips and it would run for a few seconds and die. (It appeared the fuel would run back into the tank from the carb, after choking.) I let it sit for 15 minutes, then it started ok. I richened the high speed to 1-1/2 and it seemed to run much better throughout the range, but coming down to idle it seems to almost die at first, then speeds up slightly (which it has been doing most of the time), then stabilizes the rpm and seem to run ok.

I'm confused that richening the low end seemed to lean the high end. Doesn't make sense to me. Or, is it possible with the engine running in the plane on the ground it started to overheat and cause the hard starting and changing mixture settings (I didn't run it for more than 5 minutes total, I would guess.) I'm using fresh fuel, by the way.

It is running decently, but not real confident in the engine after these runs as the setting seem to somewhat change. Do I need to put in a carb kit or maybe just fly it and see if some running cleans out the cobwebs?