ORIGINAL: Missileman
The lean hot short runs followed by rich for a while then lean hot again is exactly what the instructions in my last brand new OS engine said to do and I did. That said I am a firm believer of following the manufacturers recommendations for break in regardless of what any yahoo on the internet claiming to be an expert says, myself included (for the record I am not an expert and make no claims to be one)
My OS manual says to fluctuate between "2 cycle" and "4 cycle" operation for 10 seconds at a time, which I understood as normal, not 'lean and hot', to rich.
I agree with Missleman, I don't understand why you wouldn't just follow the directions in the manual. Again, we're not talking about some one-off, high-end plane engine, these are mostly lower-tolerance production line models. Follow the directions and keep the warranty.