This is something that we argue about in the apt. One of my roomates is a car nut, and he insists that it is fine to beat the heck out of the motor when breaking it in. He says that he will just ease a motor around for a hundred or so, then he just beats on it, hitting the rev limiter several times.
That just makes me kringe (spelling) seeing that I have always heat cycled every motor I have broken in. R/C engines and bike engines. I always bring the motors up to temp at a fairly rich A/F ratio and run them for a few minutes, then shut them off to cool down completely and repeat.
However, every ATV that Honda produces begins its' life at WOT. My father, when he was working at a Honda dealership, went to one of their factories around here for a school. Part of the trip included a tour of the factory. One workers job is to take the completed unit off the assembly line, strap it to a dyno and fire it up. Then he proceeds to pin it and run it through all the gears and then back down and shuts the motor off. From there he takes it to another person that tears it down to ship it. That was quite an eye opener to say the least
However, I would not recomend to do this, lol. I prefer my heat cycling and I would suggest you break the method in the way Yamaha suggests.
-bryan
