I have a 1999 king quad 300. When it revs up fora short time, the manifold glows orange. It does not do it at idle. I checked valve adj. and took off muffler in case of back pressure, but it still glows orange in low light. A couple of people told me its normal on some models,but I'm not sure. It starts up and runs good, otherwise. Is this something that should be fixed?