Back when I used to fly control line planes, my engines all had one speed: WIDE OPEN! Now, with my RC planes, we have a choice as to engine speed, especially on run in. Altho the directions on the engines I've purchased appear to give nebulous guidelines on run-in engine RPM, they appear to suggest WIDE OPEN STILL, even the 4-cycles. They do instruct you to run the engine VERY rich to keep them from overheating. I know I wouldn't think of buying a new car and breaking in the engine at balls-to-the-wall full speed (or any other mechanical device). I'm thinking of breaking in my new OS .40 4-stroke at less (maybe half throttle) than full-speed.
Can anyone give me any feedback from their experiences as a guide?