I wouldn't be overly concerned about the color. Looks a like some carbonizing from cheap oil? Cams are surface hardened and once you wear through that layer they wear out very quickly, so quickly that likely you would not catch the problem "on the brink" during a routine oil change but rather it would rattle/clank so badly you would already be looking for the problem. Adjust the valves, put it back together and enjoy it. RT

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