Today I had a chance to run my tuned 91 fx. It is fitted with a carb from that very OS 50 hyper heli engine and a Tower 75 muffler plus some sleeve work. I ran 0% fuel and a Rossi R2 hot plug and a MAS scimit. 14-6 prop. I was very anxious about how it would perform and if it would have a rich midrange. Well it ran great, screamed on top and idle was so low the plane just stood there jumping up and down so I had to raise the idle rpm just a bit. I let it idle for a long time and stabbed the throttle and the engine picked up almost instantly. I ran it in the midrange for some time and it was the same story. To sum it up the engine ran absolutely beautiful even at no nitro whatsoever. I wasn`t able to tach it because I was indoor due to BAD weather and my tach don`t work without good daylight. I have tached this combination before on 15% and got 12500 rpm on that MAS scimitare 14-6. All I have done to the helicarb is to lean the lowend as much as it allows (90 degrees) and set the highend needle. Based on this I would say that a heliengine could be made to power a plane, or atleast that it will not be the carb to hinder that