Really though why would a stroker os91 be too big? It weighs only 4oz more than the Os70 and if adjustments are made with the weight and CG in mind, seems to me it would be awesome. My original thoughts for not really wanting to go 91 size was for fuel conumption and concerns of the motor torque inducing twist on power increases. The more I think about this the more excited I get. I can just add throttle to aileron mixing and counteract the torque. Set up my helicopter idle1-2-3 switches for low rate and mixing on idle 1, high rate with mixing on idle 2 and high rate no mixing on idle 3. Essentially creating a precision monster capable of climbing torque rolls. Seems possible.

I agree the YS63 is the best motor of the ones I posted. I just don't see the YS63 having the vertical authority.

Robert, are you flying a YS63 in a venus? If so what is the vertical performance?