I have a YS FZ91 that I have mounted inverted on my Decathlon that I have never been able to get running just right. Is their anything special that you need to do when you have an inverted installation? I've seen pics of the pattern planes that use YS. Do they use an on-board glow on those things? I would rather not add the weight but if thats what it takes I'll do it.

The problem is getting the idle down to 2000 rpm without shaking and dying out. It runs much smoother at a higher idle rpm but still seems to die out eventually. Regulator is set flush. Transition to full throttle is smooth. Top end is easy to set. It seems to end up at about 1 & 1/4 out when I get it where I want it. I start out with an Idle setting of 2 & 1/2 out but have to turn in a little because it speeds up a little and dies out after I bring it back to idle. When I richen the low end to the point where its not speeding up after I bring it back, it Idles great for a while but still eventually dies out. I'm doing this at about 2500 rpms though because it shakes and doesn't want to run smooth when I try to get it down to 2000. When I let it run a half throttle, It seems to run pretty smooth, but when I bring the power back to idle from there it seem to die out much quicker. Valve clearances have been checked and the engine is being run static without a cowl.

I've been using a light prop (Zinger Pro 15x8) because the nose is a little heavy. Is a heavier prop recommended with this engine to help it idle? Should I reduce the fuel pressure with the regulator a little, reset the other two adjustments and try again? How critical is it to get the idle down to 2000 anyway? could it be just because it's mounted inverted?

When it dies, quite a bit of fuel drips out of the carb and drips onto the ground. I don't think it would keep coming out until the tank lost its pressure though.

This is my first YS (I've got an FZ120 still sitting in the box though) so all of this is pretty frustrating. Any ideas?