I have three of these in a modified Twinstar. (Breaking them in for an 80" JU-52.) I can get them all to keep running, but the minimum idle rpms are very fast and the top rpms tend to surge. I have tried all possible needle settings and although I found quite a lot of interaction between the low speed and high speed needles, I have not found a combined setting that will solve the problems.

I am running fresh 15% Cool Power 2-stroke fuel, 9X6 APC props, one OS F plug and 2 Horizon 4-stroke plugs. The engine with the F plug in it has 6 or 8 tanks through it and the other two have 3 tanks through them. They all have similar idle speeds and top speeds.

Can anyone suggest a combination of plug, fuel and prop that will bring the idle down to a decent level and smooth out the top end of the power curve. I am not concerned with synchronizing the engines, only getting the idles slow enough and reliable enough to land without shutting down the engines.

OBTW, the "Tristar" flys very well. Fast and smooth like an old style pattern plane.

Jim