My HYPER 7 Black Edition 21 Engine

The engine runs sweet & the car fly's BUT I get allot of bogging down (like just stuttering every now & then) the car sits there like bop, bop, bop, bop! then Bam its off again. Also I only get a stream of white smoke while pulling off, when the car is flat out there is no smoke. (Thought you were supposed to have a nice steady stream)? Now to me id think the engine needs tuning BUT why does it run so sweet when its not bogging down ?

your high speed mix screw is set to lean,a lean engine will give loads of power but will overheat very quickly due to having very little oil cooling.your engine runs sweet otherwise because she's very close to were she should be but she just needs a bit more fuel on the top end.turn the high speed screw 1- 1/6 of a turn anti-clockwise to add more fuel but there's always a trade off between power and cooling so be careful.an over lean engine will blow up,a over rich engine will give low power.