Motorcycle Repair: Engine break-in, cross hatch, rod bearings

Question
Hello Mark,

First off, thanks for taking time to read and answer a question of mine.  I used to own a '93 ZX7 out of the box brand new, broken in exactly as the owners manual suggested.  I spent about 2 yrs with various problems (carburetion mostly, and finally low compression followed by rod bearings) until I found a mechanic, Roger Jacquith (TBR Racing, Melbourne FL).  Roger rebuilt my engine and gave me instructions on break in (which didn't comply with the owners manual).  I don't remember the exact instructions, but it was more agressive than what the manual stated.  Needless to say, I never had a problem after that.  The bike ran better than ever.  I can't say it was attributed to the break in, since I had him do several mods (valve job, jetting, timing, blueprinted, etc...).  Now, as for my dilemma: I am now getting ready to buy a 2004 ZX10R and stumbled across this article:

 http://www.mototuneusa.com/break_in_secrets.htm

The break in suggested by motoman rang a bell when looking back at my ZX7.  I am now faced with two options for break in (owner manual suggested, or more aggressive) and unsure of which to apply!  Unfortunately Roger passed away a few yrs back, so I have been searching online for several days for a site that could give me an honest opinion on this break in process from a mechanics point of view.  Any insight/opinion/info from you would be greatly appreciated.  Once again, thanks for your time.

Jim  

Answer
Hi Jim,

In my opinion, the degree of cross hatch angle on cylinder wall determines amount duration and type of break in.

For example, we install new pistons and cylinders on our roadrace MC's and immediately put extreme loads on the engine during racing. Manufacturers have to design MC's under a variety of considerations and liabilities.

Cross hatch angles of 30* 45* and 60* are most common. The steeper the angle, the more oil retention and longer break in. For a racing application, use a quick break in angle of 60*.

Motoman recommends aggressive break in with any angle. He may be right.

I agree. I believe a more aggressive break in is better.
Try reviewing Kevin Cameron's "TDC" articles in Motorcycle Magazine, or buy his books. He is the King of tuners. : )

Respectfully,
Mark Shively