have you head any complaints about the FX/AX 46 running inconsistent RPMs in the H9 Funtana 40 ??

full tank or not, the motor's RPM will not stay consistent,,
we had 2 different motors with the same fuel tank (FX 46, now an AX 46) same problem, and then we put a brand new fuel tank in it and still the same problem, I even put larger fuel tubing in the tank stopper, still the same problem,, even if the motor is a bit too rich we get the same problem "inconsistent RPMs",, I even inlarged the cooling hole in the cowl,

motor is an AX 46 mounted on it's side, muffler is a side mount Pitts, fuel is Magnum 15%..
but I know fuel is not the problem cause it did it with 10% Manum in the FX46 too..

thank !!
Jim

Try the engine on a test stand. With many 3D-type airplanes, the airframe is not particularly robust. This allows engine vibrations to get to the fuel tank and agitate air into the fuel. This can easily cause running problems. If you can't get enough foam rubber around the tank to isolate it from the engine, you'll have to go to a smaller tank that will give you the room you need, or go to a vibration-isolating engine mount.

A test stand will tell you if the engine's the problem or the airframe/engine/mount/fuel system combination is the problem.

thanks Bill,, I should have added~ Saturday the motor ran fine on the first flight, then on the 2nd flight it was inconsistent the whole flight..

Jim