Exhaust getting very hot..

Hey, i have had my bike apart to do my valves, now when i start it it idles high and exhaust gets red hot very quickly. I am pretty certain my timing is correct what else would cause this? cheers.

It's normal for the WR's header to glow red at idle with no air flow over it.  Hard to see it outside in daylight but in a garage or at night it's obvious.  

Sudden high idle and excessive heat is usually caused by an air leak or fuel blockage in the carb (pilot, pilot passage)

Is the hot start mechannism stuck open - this bleeds air into the intake and causes a fast idle on a running bike

what year is it?

Are you having nightmares about your bare flesh sizzling against that red hot pipe?

It's an 08, I've also notice the idle hanging a bit I never had any dramas with it before I shimmed the valves.

Re set your fuel screw for highest idle, starting at 1 turn and the lowest idle  you can achieve with the idle screw (hot motor)

Edited by TheKoolAidMadeMeSick

If everything checks out (no air leaks, plugged passages/jets and hot start) and it still glows hella hot you may have to go up a jet or two as you have increased your compression with your valve work. That's a good thing, now jet accordingly.

My 04 WR450 exhaust header gets red hot very quickly if the bike is not moving...its normal...no worries....as soon as you start to move the red glow goes away.


Get your idle adjusted properly and don't worry about the red header when not moving.


I believe there are a couple of threads on the red hot header issue on this forum somewhere.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now