Hi Dave !

I'm in the process of breaking in a new 1.40FZ, 15% red Max fuel, APC 16x10w,OS F plug, Hatori header and pipe that ran perfect on my 140AC. I mounted the engine in the plane and started it and set the high end untill I got max rpm (8700) then backed off a few clicks untill the rpm droped to 8400 or so. The transition was decent and would idle around 3k and I could let it idle for 2-3 minutes and it would throttle perfectly. Ok great ! lets go flying WRONG. At the field the engine would idle but not transition at all it would just bog and wouldn't go to the top end unless I pinched the fuel line to clear it out. Back to idle and it does the samething so it sounds like it's really rich but why? Nothing was changed. When it won't transition to high rpm you can hear the engine change sound from the extra air being drawn in but it just will not rev up untill you pinch the fuel line off. I checked the check valve and it's fine I tried turning the reg in and out 1/2 turn and the idle screw out and in 1/2 turn from the factory settings but didn't seem to make a difference. Seemed it's throwing raw fuel out of the engine which tuurned out to be a lose header mount nut. I changed fuel to 30% Magnum Heli fuel and it does the samething so it's not the fuel. CHanged to a new OS F plug and no joy. My AC NEVER gave me a minutes trouble heck I could go a whole season and never touch the needle valve. If I ever did have to touch the NV there was something wrong and I knew I better find out what. Anyway to keep the header tight? Thanks for being here to help. Thanks for taking the time.