I have a yz450f and can't figure out why the head pipe is turning really blue. Most of the pics I have seen of other 450's the pipe is a light brown. Am I running to hot? I have noticed that my plug is a little on the rich side. I am running at about 6500' here in Colorado. Main jet is a 165, and all the rest is stock. This bike has about 15hrs. on it. Can anyone help?