colorless header pipe

I just picked up my wr 450 and noticed that the header pipe has absolutly no color to it any more. my 2001 yz 426 header pipe is still gold or what ever color it is suppose to be. has any one noticed this. i know it is running lean on the bottom because if i let it idle to long it boils over. do you think any harm as been done.

Do you mean it is silver...?

If it is silver, that is normal... it is only with heat and use that they turn gold/blue...

Don't worry about it, ride it and it will change colour...


I would'nt let that beast boil over to many times, you stand a very good chance of burning a valve or two. A blue ring of the pipe is a very lean condition, too much heat. Cool it down with alittle more gas. These Yamy thumpers are not designed to idle, run them hard, a cool down lap and shut them down. Helps if you use a small stick-on temp gauge on the water jacket to record heat temp. Mine runs around 160deg. steading, 13.5 to 1 comp. piston, 4000ft.

Just re-reading your post, and I have to add, you cannot say it is lean because it boils over when idling for long periods... no matter how rich you made it, it would still boil over... the radiators have a limited capacity, and no fan to draw air through them at standstill like a car... you're better off shutting it down if you are going to idle for more than a minute... they start up easy enough...

Don't let it idle for more than a minute or so... once you start moving again, and the air gets through the radiators, they cool down soon enough...


I agree. These bikes will boil over when they are allowed to idle for any more than five minutes. However I do like to bring mine all the way to 145-150 degrees (water temp) before I take off with it. When the bike is cold my jetting is way way too rich. Bike runs like crap until it gets warm.

Hey just remember that the pipe on the 426 was stainless. The wr450 is titanium. :D They will stay grey or blue. Good luck :):D :D

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