Well, after reading this thread I just can't stay quiet anymore. I've been racing some form or another all of my life. I've tuned or helped tune everything from go kart motors to $45k pro mod door slammers. In all that time I have learned a little about race motors. With that knowlege I have ALWAYS been against the typical nitro r/c motor break-in procedures. I totally agree with the above quote by whoever wrote it originally. There are a number of reasons why I disagree with conventional break-in methods, but the most important are:

1) heat cycling- rich and slow means not enoug heat.

2) aluminum connecting rod stretch. if you break in a motor with al rods at low RPMs and begin the mating of the piston and sleeve (since r/c motors don't have rings) then when you go to WOT the piston actually goes higher than it did during break-in and begins to destoy the surfaces.

I would advise anyone having trouble starting a new or tight motor to hit the head and sleeve area with a heat gun set to high. This will expand the sleeve and make life much easier