ORIGINAL: drbenz
I appreciate all the suggestions. I dont think its throttle linkage. As is noted it works perfectly on the ground. These are not my only planes, and not my only gassers. I have tried adjusting the idle up, but then it will roll on the ground. I have to put the idle at least 2500 to maintain idle in the air. I have consulted with the guys at my club and they dont know either. I feel that it must be a mixture problem-yes user induced I''m just not sure which direction to go. I bought a carb rebuild kit so i think i will take the worst one and rebuild it. Just a note....I have been an automotive technician for 28 years. I can rebuild a Mercedes Benz V12 twin turbo with no problem, but these small carbs sometimes have me baffled.
Tuning Walbro equipped two strokes is not at all like any car engine.
In the carb tune, a lean idle setting can also cause your problem, but so can a too rich setting. Find the lean setting where you have highest rpm at fast idle (do NOT adjust trim whilst finding that rpm). Then open the needle again until you see a slight rpm drop. Now adjust the high needle for best full throttle rpm, and open it up slightly, so the engine reaches best rpm after a short while.
From there, adjust the high needle as dictated by spark plug readings, but leave idle alone.
Remember that the idle needle supplies fuel ALLTHETIME, whilst the high needle only supplies extra fuel at more than half throttle (give or take a little)