I started construction on mine today and am using a Roto 35 in mine. The engine has been sitting in my shop for a while now and should be a good match for the plane. The folks at Kangke USA said that up to a 50 can be used but that the 35 I am using should be just fine. I'll try and give a report when I fly it. Gotta say, the fit and finish of this kit is excellent and covering was flawless. All the control rods were included and quality stuff too. They are already made up for you and suprise suprise, they Fit! (so far any way) I'll try to get some pictures tonight and post 'em for Ya.