headpipe glowing is this right?

[WhiteZrider]

Ok my z400 is jetted spot on and I've never had any problems with it over heating or nothing, and tonight while riding with my cousin putting in mid 2nd gear I noticed that my head pipe glows a dimmer to bright orange color. The fan seems to come on at different intervals like if I do one 2nd gear run shut it off the fan will come on and if i go and do it till it gets red again for the same amount of time and speed it wont turn on when i shut it off. My question is I figured that it is liquid and fan cooled and the jetting is right it shouldn't do this.

[Eviltanker]

I would check your jetting, maybe thee is some dirt in one of the jets.

[KENNY HEMMINGS]

ALL THE YFZ'S DO THAT, THEY SAY THAT YOUR OK AS LONG AS IT
DOESNT GLOW PASSED THE HEAT SHIELD, GLOWING SHOULD
STOP ABOUT WHERE THE HEAT SHIELD STARTS, PART OFF THE
REASON THEY DO THAT IS JETTING"WHEN YOU GO BIGGER AND ADD MORE FUEL AND AIR" BUT ALSO THE TYPE OFF METAL THE
HEADER IS MAD OUT OFF.