YZ450f Crank

I've decided to overhaul my 2006 YZ450f. I've removed the head, cylinder, and piston, all seems ok. But I have noticed blue marks on the crank flywheels, adjacent to the big end pin. Is this from manufacturing or is it from overheating during operation?

That's heat treating, and is present on all YZF cranks. If it had gotten that hot in operation, the big end of the rod would be blackened, if it survived at all.

Thanks, thought as much, it's local to the bigend pin so probably from heating to allow the pin to be pressed in.

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