Engine performance is dependant on how well the piston rings seal against the cylinder bores. I my experience, also voiced by Velocette in the 1940's, don't be too gentle! The motto then was, "Run them in fast and they stay fast".
You need to create sporadic high combustion pressures to press the rings tightly against the bores, otherwise the bores will glaze and you will never fully exploit the engine's potential. When I rebuilt the Norton, I started with ordinary mineral oil, rode like I stole the bike (using lots of heavy "throttle-on / throttle off" bursts) and changed the oil frequently. The engine never burned any significant amounts of oil, did not smoke at all and went like stink.
It is interesting to read how the Aircraft engine manufacturer 'Lycoming' insist that their engines are bedded in. Google that one - its good bedtime reading
The following link is well worth reading thoroughly:-
Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power
Think about it. On the production line, the likes of Honda, Yamaha etc bench run all their engines at full throttle before even sending them out of the factory. But they then advise the new owner to pussy-foot along for 1000 miles or so. Many race bike and racing car engines are built a few nights before a race and then driven flat out. They don't drive them gently around the streets, keeping on light throttles below 50mph!
I just realised - this may need a separate Topic, since it deviates from the "Muck" thread.
