Since everyone seems to hear differing advice on break in, and also often wonder WHY a break in period is needed, thought I'd start this thread.
During break in, one of the major concerns is getting the piston rings to seat to the cylinders properly. You NEED some friction to accomplish that, and the natural breakdown of the oil lets the friction build at a nice rate to allow the rings to seat properly. (This is also why you NEVER, EVER break in a fresh engine with a synthetic oil.)
If you do not seat the rings properly, you will have problems ranging from excessive oil consumption when you do switch to better oil, to lack of compression or piston damage. Then you get to rebuild the engine top end and go through break in all over again.
I follow the break in recommended by Rick Petersen, who has built many race and street motorcycle engines in his days.
1: Find the crappiest straight 30wt oil you can find. Put that into the rebuilt
engine. (NOTE: If you bought a new bike fresh off the showroom floor, DO NOT change the factory oil!! This use of straight 30wt is ONLY for engines that have been rebuilt.)
2: Run the bike, generally not exceeding 1/2 of redline RPM's. (An occasional very short blip a few thousand over half will not hurt. But DO NOT ever get more than 3/4 of redline RPM's.) Also, DO NOT drone along at the same RPM for extended time, keep varying the revs.
3: As you get closer to the 600 mile mark, you can push a bit harder...still stay under 3/4 of redline, but you can be a bit more aggressive.
4: When you get to 600 miles, change the oil and filter (and in the case of the Ninja or any bike with a filter screen, clean and inspect the screen.) A SMALL amount of very fine metal particles trapped in the filter is ok, big chunks or a large amount is bad.
5: Refill with your preferred oil (but stay away from synthetics until AFTER 1,500 miles)
and start to run the bike normally, stay away from extended high revs or redline for a few hundred miles just to be safe. After that, ride as hard as you want to...within your abilities of course.
I rebuilt my FZ750 (it redlined at 12,000) with 40k miles on it, followed the break-in I just described and rode that bike for another 45,000 miles with absolutely NO engine issues at all. It never burned oil, had great compression and ran like a champ. I changed oil AND filter every 3,000 miles max. (Actually had to change it at 3k, much beyond that and the shifting would get very notchy.)
Ninja Boy followed that break-in schedule and it runs great and is no where near as cold blooded as it was when I bought it.
The factory break in described by Kawasaki is unrealistic and IMHO would result in an engine that consumes more oil and would never run well. It is too conservative (and since the 5k rpm equals about 40 mph in sixth gear it would be impractical on most roads too) and the engine can tolerate a bit more than they recommend. (Remember that most of the things like break-in instructions, etc are written and/or edited with liability in mind which is often not in line with the real world.)
** DISCLAIMER: FOLLOWING MY BREAK-IN PROCEDURE MAY VOID WARRANTY IF THE DEALER OR MECHANIC DECIDES THAT YOU DID IT WRONG, SO BE CAREFUL. NEITHER MYSELF OR ANY OTHER PERSON POSTING IN THIS THREAD WITH ADVICE ARE IN ANY WAY LIABLE FOR ANY FAILURES, DAMAGES OR VOIDED WARRANTIES CAUSED BY FOLLOWING THE ADVICE GIVEN, WHETHER THE DAMAGE IS CAUSED DIRECTLY OR INDIRECTLY AS A RESULT OF THE ADVICE GIVEN!! **