Anecdotal evidence, but when my father was working at Honda of Marysville he told me "Break in period? psssht... the drivers go hammer down right off the assembly line, stand on the brakes to get it parked, rinse and repeat all day".
As has been said, modern engines don't need an extensive break in period. Just drive the thing.
Different engine, but similar principal, and since we're sharing hard core factual anecdotes...
I do a piston/rings/pin every 50 hrs or so on my YZ250 2 stroke. Lots of guys still follow the "baby it, do 3 full heat cycles, re-torque everything" method. I do the "let it get warm, check for coolant leaks, then WFO method". Anecdotally, my bike runs stronger than my buddy's bike that follows the former method and shows less blow by when it's time to do another one.
JG Pasterjak said:The cars that we see in the press fleets get hammered like rented nails from the moment they come off the assembly line. Mechanically we never see issues.
To be fair, press fleet cars usually get turned over after the first oil change. I’m not sure they’re a good test of longevity :)
doc_speeder said:Different engine, but similar principal, and since we're sharing hard core factual anecdotes...
I do a piston/rings/pin every 50 hrs or so on my YZ250 2 stroke. Lots of guys still follow the "baby it, do 3 full heat cycles, re-torque everything" method. I do the "let it get warm, check for coolant leaks, then WFO method". Anecdotally, my bike runs stronger than my buddy's bike that follows the former method and shows less blow by when it's time to do another one.
I have heard enough engine builders say that an engine makes more power on the second set of rings on a given hone job (meaning, don't hone when re-ringing) that I'm thinkin' the break in period isn't for the rings so much as it is to clean off the sharp edges of the bore's honed surface.
The other bit of trivia is that ring gap will open up .001-003" in the process of breaking in...
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