2001 400ex valve coating question

A coating of carbon and other by products of combustion will be deposited on the valves - the exhaust valves collect more deposits than the intake valves, but to answer the question, most valves are black oxide coated when manufactured to prevent corrosion prior to installation or sale. I glass bead blast the valves and cylinder head prior to lapping the valves and reassembling the head.

The only thing I can say about the appearance of the valves is they are running cold or in an over rich air/fuel mixture. My valves come out with just a light tan coating of combustion by products on them.

I don't know the history on it, the PO never rode it because it needed work when he bought it. Engine is stock as far as I can tell, it has a white brothers slip on muffler, stock air box with a K&N filter, jets are stock too. I want to run a UNI filter or something different then the K&N which will then probably make it run richer. Any suggestions for a filter and jetting?

If it has a foam filter (Honda, UNI, TwinAir or other foam filter) and a lid on the air box, the only change to jetting will be a little larger main jet so it is not lean when wound flat out (WFO) - for all other engine speeds stock jetting should be fine.