@cory_lax, you incidentally brought up a good point to discuss; break in will be different on 2 stroke vs 4 stroke, and diesel vs gasoline (both 4 and 2 stroke diesel, yes there are 2 stroke diesels). And also that the mentality on this is limited to only thinking about the simple things like the rings, what about the cam bearings, cam lobes, timing gears, or belts, in some cases supercharger belts, main bearings, con-rod bearings, wrist pins, end seals, transmission gears, transmission seals, valves, valve guides, valve seats, oil pump gears, etc etc. these are all surfaces that need to be bedded or broken in. In fact if you take a set of bevel gears like in your leg and run them at full speed right out of the box you will see significant wear or damage will occur as the machined surfaces actually need to be given time to polish each other, they will generate heat and shearing moments as they interface, that’s why the first leg oil change always comes out with a significant quantity of metallic particles. This happens with every gear based power transmission system and the size of those particles will be dependant on how the gears were broken in. So the complications from improper machinery break-in often goes unnoticed at first or don’t present in a way you would expect. For example, most oil pumps in engines are either a basic 2 gear system, or cycloidal, both are very easily damaged by metallic particles which is why there is a large particle strainer in the sump, but even small particles wear them down quickly resulting in low oil pressure. here is the catch, you went though break in and everything seems fine, but from the start of the engines life you have reduced the capacity of the oil pump and are feeding your engine less oil than intended for the rest of its life, that’s the start of what separates a 3000hr engine from a 6000hr engine. but few people actually keep a motor for that long, it becomes someone else’s problem.
The issue here really is all the people with anecdotal experience and opinions on this are not going out collecting data, taking apart and testing the machinery to see how much wear occurred under what conditions, and measuring everything to within 0.001 tolerance, and doing this tens of thousands of times over decades.
Even motorcyclist magazine laughably preformed a “test” to disprove this, by taking a pair of used cb300f motors, replacing the top ends only and then broke them in with the standard method vs ride hard and fast. Then measured the compression and leak down, and finally concluded it made no difference. Now I don’t have time in the day to break down how ineffectively their “scientific method” was carried out, but I am good with analogies, this is like taking twins to the doctor, one is terminally ill with a brain tumor, the other is fine, and you ask the doctor to tell you which one is going to die by only testing their ability to breath and hold their breath.
And back to my lunch
