Well, before I didn't bother to clean my brand new engines before breaking it in. Most of the engines that I have used were the OS ones. When I started using the Nova engines, a friend of mine recommended that I take the engine apart and clean it. That is what I did and to my surprise it had some minute debris in it. I'm sure glad I took it apart and cleaned it. Also, I put a few drops of after run oil in the engine everytime I take the engine apart. This is to keep the engine internals oiled before breaking it in or running it again. It sure helps to keep the internals well lubricated as to running it dry...