ok cool, the serval should be slightly more efficient on fuel. If it was jetted for your altitude, it SHOULD be close and possibly rich. (If serval was jetted properly for your altitude and current temp) All the same, I would jet up a touch, run it on new plugs 1-5or 6 if you can and shut it down. Pull plugs, post pics for us of plugs and we can guide you from there.
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