My YZF runs great but sometimes the exhaust pipe heats up to a bright cherry red from the head all the way to where my leg rests. I was thinking that maybe the jet size was wrong but I have never worked on a quad and don't know where to begin. Does anyone have any suggestions.

 

It's normal! Don't jet by the headpipe. Jet by how it runs. Checkout one of the YFZ Forums for more details on jetting.