For those that haven’t followed the story on backcountrypilot, I figured I’d post here - Bane is ALMOST back in the sky after some adventures in carb tuning over these past days.

The data collection on this planes engine started about a week ago when I decided I was done hunting for the perfect idle and power settings per the rotax manual and forum suggestions, and I went back to the method I’ve used on every other engine - an air fuel meter and some time. The results of this installation and data collection showed that almost everything said about the 912 and Bing carbs on these forums to be complete nonsense. “Return it to 100% stock” leaves the engine at a ratio of 7.9:1 on the AFR. Instead of 1.5 turns out on idle mixture screw, 5/8 of a turn out placed is at 12.8:1 - the ideal ratio.

secondly, needle in clip 3 position, mid range at 8.2:1 - move needle to 2nd clip position from top, arrive at around 11.1:1 on the ratio - rich but still better.

lastly, main jet at wide open throttle runs 13.4ish:1 which is too lean. A bit of polish to clean it up today and I’m sure I can get it between 12.8 and 13.1.

Moral of the story, tune your carbs to your engine. I’ve never in my life ran across an “all inclusive “ carb setting that works for every engine the carb is bolted to. Sure, you can go buy a carb and turn some screws and get an engine to run, but that doesn’t mean it’s running right.