"OK, I've been looking into this a bit more and come up with some info as well as a bit of an explanation for why everyone seems to have such different break-in procedures.
So what should you do.... run in soft, or rag it out? Turns out a bit of both, and I'll explain why:
Apparently the first thing you want to do is the bearing break-in, ie: make sure the camshaft lobes and lifter heads get properly lubricated (there by prepping them for the REAL break-in).
To do this you want to start the engine and (while in neutral) immediately get your RPM's into the mid range, varying it up and down by ~2000rpm for about 15 minutes total. The Reason? Well the camshaft lobes and lifters get their oil from spray coming off the connecting rods. At lower (idle) rpm's they DO get enough oil to run, but not enough for break-in. Running everything faster gives you a bit more of the oil splashing action.
This honestly is something that should have been done AT THE FACTORY immediately after the engine was built. If it wasn't it's no biggy... as long as the engine hasn't been run under load for extended periods at high temps you can still do this. If it has (been run hot/hard), then you're screwed and the camshaft and lifters just won't seal properly.
After you're done you should change the oil.
This procedure pretty much accounts for the "change oil ASAP" rule that most people agree is a good idea. The main different being that you want to do this BEFORE you load the engine.... not after (as by then it's too late).
Next is the actual break-in.
First start up the bike and let it get up to normal operating temp, then find yourself some hills and ride up those suckers. We're trying to really load those rings and get the piston, cylinder, and ring to break in well. You want to really heat up the engine and work it hard as it's this heat and load that will ultimately burn the glaze off the cylinders and let everything seat well.
Please note that when I say ride it hard, I'm talking about high gear (4-6), uphill, with MODERATE rpm's, and running downhill with engine breaking (in a lower gear of course). DO NOT PEG IT! If you run the engine TOO fast all you will do is reglaze the cylinders (same thing happens with new brake discs that are over strained when new... they glaze over).
After running the engine hot like that you need to let it cool down slowly. Run it under moderate to low load, at moderate rpms, while slowly getting down into lower RPM's and finally parking it. The trick is to sustain the high engine temperature and bring down the temp as slow as possible. Aside from just being good for the engine (see: motorcycle racing, cool down lap) it also helps to further temper (strengthen) the engine and it's many components.
This will break-in the engine in a couple hundred miles or so, at which time you will want to change the oil again.
Now it seems a common misconception is that if you ride the bike hard, or ride it soft (take your pick) that it won't break-in properly. Well if by "properly" you mean "in a timely manner" then sure. Make no mistake though, no matter WHAT you do the engine will seat eventually (more or less), it's just a matter of how long it will take. The single exception to this being that an engine that is NEVER pushed may never seat fully.
OK, so why do the manufacturers tell you to go slower and ramp it up over time? Safety mostly. It's far more likely that something is going to break or fall off when it's brand freaking new, than it is at 10,000 miles. By starting off slow you gradually "shake down" the bike, increasing the strain on it over a period of time, and hopefully identifying any mechanical defects before they become a life threatening problem. This also gives you (the rider) time to acquaint yourself with the bike. Every motorcycle is different, and as such will respond differently. Anyone who has ever switched from one bike to another knows what I'm talking about. More over, breaking in a new bike isn't JUST about the engine. It's the tires, the brake discs, the rider. Lots of little bits that all need to be working together in the right way.
So, long story short... keys to a good break-in:
Proper Lubrication
Proper Warm-up
Heat+Engine Load (both acceleration & deceleration)
Proper Cool down
Oh, and if you blow up the engine... that's what warranties are for."
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