Re: breaking in new 4stokes
The manufacturer's recommendation for breaking in my 90 hp Yamaha four stroke was to run at 2,000 RPM for 1 hour, run at 3,000 RPM for 1 hour, and then run at any other speed for the remaining 8 hours EXCEPT do not run at WOT for more than 5 minutes at a time during the remaining 8 hours.
There are probably a couple of things going on during the break in period with the bearings and other surfaces, but seating of the piston rings is definitely happening and is important. I have heard reports of running four strokes too lightly during break which can result in the engine "making oil" later. (See posts above.) At the same time, I have heard some folks suggesting that one should "run it like you stole it" during break in to avoid this problem.
Being an engineer type, I tend to think the manufacturers know what they are talking about so I went by the book.

Not only that, but these engines are expensive so I'm going to do everything I can to keep it within warranty and extend it's life into the year 3000 if possible.