Hi, Newbie in town. Im restoring an 85atc 200m and wanted to know if the cylinders were coated with anything. I have the typical stained up white looking corrosion on mine. I read the posts about using oven cleaner and other product. Do I need to spray a heat proof clear on the cylinder or paint? Also when you change out your cam chain do you have to replace the sprockets. I know a new chain on old sprockets is a no no but the crank sprocket is not something I want to mess with. Thanks!!