Is this purely cosmetic?

[flynrider]

It takes a lot of heat to discolor the chrome plated can like that. That looks a lot like a bike that I saw at my local shop. One of the mechanics left it idling outside to warm up the oil for a change. He forgot about it for over half an hour and by the time he remembered it was close to meltdown. Ultimately the oil that came out of it was coal black and the consistency of water. I really wouldn't trust the longevity of an engine that had been through an extreme heat event like that.