Ed Moorman wrote an article on the SK and due to it's design I follow Ed's break in to the letter. If you didn't know I'm a big fan of Ed and use his how to stunt flying lessons he wrote in RCR. Other then the SK I'm pretty bad about breaking in. When I first started RC I was using the OS LA, SF and FX engines. Breaking in was never a big deal with the guys at the field either, just start them up, run them until they would hold a tune and go fly. By the end of the day all was good. These are not ringed engines though. I never saw anyone giving a lot of thought to break in until the AX model came out?? Other then the ring seating and a little bit of valve and bearing wear in I just can't understand all the worry about breaking in a four stroke or ringed engine. Some engines like Moki can suck up a lot of fuel before the ring seats and the engine comes alive. That's a lot of ground work. That's why I say, maybe Bax can enlighten us all on break in. Bill sees these engines day in and day out, understands everything about them so I figure he is the person to be asking why. When I have an OS problem he is my go to guy.