Jeez....this has all the makings of another oil arguement.
There are a lot of things involved with engine breakin and not all engines are the same. One of the problems is that everyone (including Motoman) tries to apply one set of rules to everything assuming they are best.
Given the accuracy of machining and finishing of modern engine surfaces it is doubtful that you could hurt anything doing a Motoman breakin. In my opinion, it is also doubtful that anything will really be helped. The engine breakin will certainly happen quicker but I have a hard time understanding how it will be better ultimately.
Many of the admonitions in the owners manual regarding breakin address more than just the engine.... Transmission, final drive, brakes, etc... all fit into the "break in" category.
Brakes, for instance, need to be bedded in for maximum braking effectiveness. Use the brakes too hard too soon without bedding them in first and they can be damaged. So...tell the owner to "take it easy" on the engine and they will likely take it easy on the brakes, too.
The legal eagles also have their say. I can only imagine the lawsuits from publishing a Motoman-like mandated breakin procedure for the average rider or the person that bought an FJR after not riding for the last 20 years...or ever before.
So...bottom line is that there is a lot more involved in the recommended breakin procedures than just what happens to the engine and they must be considered too.
From an engineering standpoint it is certainly good to load the engine for breakin and to cycle the engine from load to overrun repeatedly.
One thing that is not so obvious about ring "seating" is that the rings constantly move on the piston. So the idea of the ring surface "mating" to the cylinder wall is a little bit misunderstood. If you hold the engine at heavy load at 6000 RPM the piston rings are constantly rotating on the piston despite the idea that they stay fixed and mate to a specific part of the cylinder wall. There have been radioactive tracer tests run on rings and it is actually possible to measure the ring RPM on the piston! Unloading the rings with engine overrun or engine braking also tends to move the rings around and move them in the grooves which helps any mating to occur.
One of the most important ring 'breakin" items that is not even mentioned is the side of the rings mating to the sides of the ring lands. The face of the rings seal to the cylinder wall (with the help of the oil film) but the seal around the backside of the ring is maintained by contact of the SIDES of the ring to the SIDES of the ring land. On a broken in engine the sides of the rings show far more burnishing and the sides of the ring lands show extensive burnishing which generates the microseal necessary. In addition to sealing, the piston rejects heat thru the lower rings to the cylinder wall so the contact between the side of the ring and the side of the ring land is necessary for this. Similarily, the upper ring will reject heat to the piston to stay cool which also relys on the side contact.
One hazard on some engines during breakin if they are run too hard...i..e...too much heat poured into the rings and piston is that the side surface of the piston ring lands can overheat and microweld. This pulls smalls pits of material away from the aluminum of the piston and ruins the chances of good contact between the sides of the ring and the ring lands ever happening. This is a real possibility if the rings/piston ring lands are not perfectly compatible or there is inadequate prelube on the rings from assembly or the rings are simply not allowed enough time to burnish the ring lands before continuous load is applies.
I have looked at rings run during breakin and for thousands of miles and it is sometimes hard to detect the "wear" or "breakin" pattern from where the rings contact the cylinder wall. Basically, little or nothing happens on the face of the ring.
In addition to the rings moving around on the piston they also "expand" and "contract" to account for minute lack of roundness of the cylinder wall. So the rings are always moving in or out of the ring lands as well as rotating on the piston.
The surface of the cylinder wall always has some small surface asperities that are wiped off by the rings during the first few moments of operation. Beyond that, the idea of the factory "honing pattern" disappearing is an old wives tale. I have seen engines with cast iron bore that still had the OEM honing pattern clearly visible with little or no wear evident on the cylinder wall after 200,000 miles on the engine. The factory honing pattern is designed to hold oil on the cylinder wall (that is what seals the rings to the cylinder wall) so if it disappears the seal disappears. Even the Nikasil and aluminum bore (Reynolds 390 ne. Vega/Porsche/Mercedes/BMW Alusil) surfaces have a grain or pattern to them that holds oil much like the honing marks do so that can never dissappear. Hard to believe that the Motoman or any other aggressive breakin schedule can affect this in the long term. Might make the surface irregularities or "high spots" disappear sooner but not 'better"....
I have also seen engines broken in hard on dynos and gently and there has never been any difference in the ultimate power output of the engine. The harder the breakin the faster the power will stabilize but either method always seems to get the same results within engine repeatability. That is part of the problem with proving or disproving the Motoman procedure. You can only breakin the engine once so the only way to compare is with two separate engines and there is likely more difference in the engines no matter how careful you are building them than the breakin will ever net. The real advantage to engine builders and dyno development programs is that severe breakin schedules get the job done fast....so they get used a lot. Doesn't necessarily make them "better"...just faster!!
BTW....do the Motoman type breakin on an older, pushrod type engine in your muscle car with a cam-in-block design and a cam-driven oil pump (via the distributor gear) and you are very likely to take out the distributor gear. The distributor gear in those older engine designs was the weak link during breakin due to the high oil pump loads. The distributor gear load bearing capability increases dramatically within the first 20 or 30 miles of normal driving so too much RPM with a green cam and distributor gear would easily wipe them out. Caused many of the old wives tales about roller cams and bronze distributor gears, etc....LOL.
One could write a large book on engine breakin...which leads to all the old wives tales, motoman breakins and oil-like breakin threads.
