I am by no means an expert, but I do have a lot of high performance engines around the house (my snowmobile is over 165hp now) a am quite a motor head and study this stuff. I see a lot of people using the factory recommended method for breaking in this engine, and others saying that it's not a good idea, but I didn't see anyone say why. The reason is because the cylinder is tapered at the top. As the engine builds heat it expands so the cylinder is nearly cylindrical when it's running, but binds up to some degree when it's cold. If you don't get enough heat in this engine then the tolerances are tight and you run the risk of running the engine at high rpms with out proper piston bore clearances.

Because of these reasons if you run it so rich that is sounds like a 4 cycle, then you are really cooling down the piston which causes it to get pretty tight.

What others posted about running on the rich side, with a 2 cycle sound for 2-3 minutes heat cycling will cause the machined surfaces to mate while keeping good tolerances.

Just my $.02.....