I have heard in the past that the Royal engines where OS knock offs. That's a good thing. I'm not sure exactly what you mean by wanting the specs of it though. Bore, stroke, weight, and power output? Those things are lost in time. You would actually have to measure those things with the engine you have. Those specs are irelevant anyway towards your goal of flying. Find a kit that takes a .20 to .30 engine and fly it. The engine should be good unless it was abused.