2004 YZ450 header pipe glowing red

Anyone have this happen? thnx

read the faqs thread thanks Im a little slow today :banghead:

After I rebuilt my 03 with a hole new top to bottom rebuild really mild head work , stock bore & stroke , pro curcit 496 slip on , I had to re jet cause 5 seconds after fireing it up after rebuild it went nuclear red glowing hot , I think I did 188 on main and 75 pilot jet ? ( It was a while ago ) pump gas 91 octane , I live in southern California so set it for sea level with those jets and needle in stock location , maybe this helps ?

Oh and my 06 yz450 will do that still after rejet , old top end , full maga bomb 4.1 system , stock engine and gas that been in the tank for over a couple months ( inside a cooler garage no sun light ) old gas will do it .

That jetting is ridiculously rich.  (I live in SoCal, too).  My advice is to ignore that advice.

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