I run in all the engines i build hard. I let them warm up, & go through the gears easy at first to ensure no binding in the tranny or whatever...then i really tan them.
Very rare does a problem occur, & never because of this method...............i say rae because i build alot of engings, both four, & two stroke.
I built my heavily modded K5 , & ran it in real hard. My bike is piped, shaved head, ported, lectron carb, fancy reeds, etc, etc, etc.
Since the build i have burned well over 100 gallons of C-16, & she still runs like a raped ape
..................& i have this thing wide open for very long periods.
It never ceases to amaze me on how tough it is
I will mention that i do not burn synthetic on the first tank after rebuild....but use 50-1 synthetic after that.