It's my understanding with the current manufacturing technology it's not necessary anymore, on new cars, now there may be differences in motorcycle engines as I am not as familiar with those. With that being said we ask the customer to come back in 500 - 1000 miles for a free oil change on the engines we build and install. We do this for a couple of reasons, we change the oil getting any of the contaminates that may have been the result of the rebuild and break in, it also allows us a chance to double check our work and make fine tuning adjustments.
Here is a related excerpt from a popular mechanics article
The ritual of breaking in a new car is part of the body of knowledge
we refer to as conventional wisdom. It’s not necessarily wise, and the
technology of building a modern automobile has evolved to the point
where a lot of “wisdom” is obsolete. Few cars specify a break-in
procedure anymore, simply cautioning you to avoid extreme acceleration
or extended idling for the first thousand miles or so, and there’s
little in the way of extra service up front.
Engine Cylinder Walls
Piston rings don’t rely on their spring tension to seal against the
cylinder bores. Instead, combustion gases work their way between the
rings and the piston and force the rings outward. During the first few
minutes of engine operation, it’s important that the throttle be
opened pretty far at lower rpms to provide this high pressure.
Otherwise, the rings won’t burnish the cylinder walls properly, and
the engine will have high volumes of blow-by—which means excessive oil
consumption and shortened engine life. If you’ve ever seen the car
jockeys who drive new cars off the end of the production line into the
storage lot, or the transporter drivers zipping up and down the
car-hauler ramps, you’ll realize that this all-important step has been
performed for you many times. If you’re installing a new engine,
simply give it a few seconds of wide-open throttle in a high gear. For
the first thousand miles, avoid constant speeds and throttle settings.
If you commute in normal stop-and-go traffic, you’ll be fine. I advise
against cruise-controlled sojourns across Nebraska.
The admonition to keep engine revs low for an extended break-in period
stems from the days when bearing and crankshaft manufacturing
tolerances were far less rigorous and lubricating oil wasn’t nearly as
good. While modern engines are assembled to much the same design
clearances, the tolerances are much tighter, meaning the variability
is smaller, greatly reducing the possibility of a tight spot.
Redlining a fresh motor is generally a bad idea, but there’s no reason
you shouldn’t drive normally. I would, however, avoid top-speed
testing, drag racing or towing heavy trailers for the first 1000
I customarily change the oil in a new engine after about 20 miles, and
again at 1000 or so. That 20-mile oil, you would think, would look
pretty much like fresh oil right out of the bottle. Wrong. It usually
looks more like metal-flake paint, iridescent with tiny particles of
metal worn off rubbing surfaces inside the new engines. After a few
hours of operation, this completely normal phenomenon slows down as
the rings, camshaft, lifters and bearings burnish their respective
Read more: New Car Care – How to Take Care of a New Car - Popular Mechanics