I just installed a MDS .48 Heli engine with a macs header, tuned for maximum rpm's & 6 ounce rave container(1 3/4 " x 6 ")in my Top Cap.The stinger is 1/4" id 2 inches long ,the engine is running a 12.25x3.75 APC prop it was getting 11,500rpms before,now its getting around 12,700,a pretty good gain.

The engine mixture is not set too lean in high or low.If i pinch fuel line while idling the engine speed will increase after a second or two so the mixture seems to be fine.The problem is that while its on the ground I can run the engine upright in a hovering position and it will run perfect with good throtle response,pick-up,and no hesitation,It is not overheating.But when i try to hover the TopCap in the air the engine will start to bog down after a few seconds and it will usuallly quit.

I have tried richening and leaning the mixture but no success.I have hit the ground pretty hard twice because of this.I cant figure it out because it has excellent power with unlimited vertical that is until I try to hover the airplane then the engine will usually act up.