I bought a crank on ebay. It was from an engine that had never been bored. I checked run-out, rod side-to-side play, no up and down play. I replaced outside bearings for good measure, got new seals and assembeld crank cases. After mounting in bike frame, I happened to notice that one side of one rod was pink at the bottom end. Is this bad? I took pics of both rods. see images
I posted this in another thread:
Steel turns blue at 520°F and purple at 575°F. It becomes incandescent above 800°F. That con rod got pretty hot at least on that side.