i have an 05 yfz 450, i took it out today and the pipe seems to burn hot, it doesnt get red but its a bluish color, is that normal? and the fan doesnt click on, i dont know if only turns on when the engine becomes extremly hot or if it is broken, does any one have any ideas, the coolant is filled like halfway, should i change it or just fill it?

 

The pipe seems to burn hot, And the engine temp are not exactly related. All my YFZ450's pipes get hot. The head pipe even glows in the dark. As far as the fan comming on, mine only comes on when I work the motor hard when i am going slow 04 and 07. Now my boys 05 the fan runs at least twice as much as the other two. I think it is from the more restrictive exaust. Your coolant level should be ok.

 

I have a 426f and the pipe gets super hot too, never been a problem though.