Some cylinders/engines come from the factory with that coloring. I believe the only way to get it off would be to glass bead it. If you do that, be sure to very securely close off all openings, as the glass beading process would ruin the bore surface.

Myself, I just run them that way. I see this one is a Homelite. Most of the Poulan engines are that way as well. The darker color might very well dissipate heat better....

AV8TOR