I bought a Evo 61 engine to try. Using thee same size/type of prop the man claims to get 12,0000 rpm. I am lucky to get just over 11,000. Out of the box it was way too rich on the low speed. Fuel burbling out the top of the carb and would instantly die if I touched the throttle. After some adjustments it ran ok but not great and seemed to lose power with every flight. I have read more than few reports of this happening with other Evo engines as well. Brought the plane in, tyed down and throttle up to try and find out whats going on. At high throttle you could see the low speed idle knob turning! Pulled the engine and its sittting on one of my benches now. [>:]