I'm having a similar issue to this here. I'm running a 3W-80xi with a 26x10 prop. We've been having issues with the engine running rough and cutting out at idle lately and have been trying to retune the carb.

We start by tuning the high end 100-200 rpm lean of max achievable rpm - this works fine. When we go to tune the low end the throttle adjustment screw requires a lot of screw in to even hold an idle. We've then been leaning the low needle which causes the engine to rev up allowiing the throttle adjustment screw outwards. When we go about this process the engine revs up without any hesitation however, it doesn't want to come back down the idle rpm, it hovers around 600-700 rpm higher than idle and will only come down when the throttle is "pulled" closed further. We've also seen it sometimes hunt around to find an idle, varying +/-400 rpm around a little above idle.

From the posts above, it sounds like we're leaning the low needle way too much and should even consider running slightly rich to avoid the engine quitting in the air.

Does anyone have any more in-depth methods for carb tuning or any suggestions to on how to proceed? Also, does anyone with experience with this engine have recommended rpm settings for full throttle and idle? We're currently shooting for around 1800 rpm at idle at 5800 at full power.

Thanks in advance.

-Rick