I have an older OS 45F 2 stroke in my Harrier 3D. First I had bubble in my fuel line and fixed that. Now it runs at high rpm and high idle, but won't idle down for crap. It still has excellent compression. It also loads up too. If I adjust the low speed for decent transition along with the high speed it gets better, but the lower idle just isn't there like it was when mounted upright. I previously had it mounted upright in an old trainer and it ran great. Now it's inverted and running like a dog. I bought it for next to nothing, but would still like to use it. I run Wildcat 10% with 18/20 oil content. Is the fact that I inverted it making it run poor or just a tuning issue. The fuel tank is inline with the carb as far as I can tell. I'd really like to get this plane in the air but haven't because of it not running reliably.

Thanks,
Tim