Plugs, running lean?

[G.Rossman]

Pulled the plugs while checking valve shims.  At the end of the threads it is black but the actual electrode area is white. They are an NGK plug.  I was thinking about doing a K&N filter and maybe a slip on at least.  Don't want to end up way too lean, but is it already lean?  Had a bit of backfire before I took it apart a couple times just revving it in the garage, bike is new to me so I don't know about street performance.

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