Glowing headers?i

[alping45]

I just had my 400ex out at night for the first time and noticed the first few inches of the headers were glowing a little after some moderately aggressive trail riding. Mods are: White bro's e2 slip on, uni air filter with no airbox lid on, 40 pilot jet, 160 main jet. Its an '07 so the needle is not adjustable.
Is this a common thing or is something wrong?
Next time before I take it out I plan on shimming the needle up, maybe its a little lean as is causing the glowing head pipe?
Any input?

[BigBore24]

here is a pretty good discussion about that very thing. maybe a month ago

http://www.exriders.com/vbb/showthread.php?s=&threadid=340814&highlight=glowing+headers