I have several small air cooled engines that I own. Any of them I bought used. But I have had several that I bought new. I would have to agree with the others with the others that these engine take a good 20 plus hours to be broken in. I have a Tecumseh on a generator that had some where around 35 or so hours on it before it stopped using oil. But I have another tecumseh that was also a 5.5 horse that only used oil for the first 15 hours. Both of those motors ran strong and still are. I just bought a 5.5 horse briggs and stratton ohv intek that has about 10 hours on it and hasn't used any oil at all. But I still am gonna wait another 10 or so hours before I will start using syn. oil. From what I have learned and heared I wouldn't consider one of these engines to be broken in till it getts 20 hours on it.
As to how to break it in I have always run my engines run just below top speed and under a light load. I hate to hear that people go out and run the **** out of a brand new or rebuilt engine. But I also have to tell you that it isn't good ether to just let the engine run at or near idle without a load.
