What ROTO is it? The 85cc twin or the 170 quad?
A friend of mine had the 85cc installed in an aerobat and he had some problems with the fuel supply, as the engine would quit from fuel starvation once in a while. But adding a fuel pump cured the problems completely.
I guess it had the same problems with the internal pump as the Moki radials does, where adding an electric fuel pump works wonders on the engine.