cherry red header

i have a 02 wr 426 and i jsut put a fmf power core 4 muffler and a power bomb header with a stage 1 fmf jet kit i went weith the 170 main jet as it said to use in the paper with the kit but anyways i rode the bike today and after riding for a while riding hard that is i noticced the header right where it bolts to the cylinder was cherry red what is making it get that hot and what can i do to fix it or is suppose to be like that with the after market header this is the first fourstroke ive ever had so not real familiar with it


There are several threads about this here so please a a search. But yes it is normal

Timo Mc

i dont believe that a cherry red header WHILST riding is normal. It may be indicative of LEAN jetting.

A red header on a still, idling bike is indeed normal.

Was it dark out when you noticed it? Iv'e noticed that mine looks pretty red at night but you can hardly notice it in the day time. It could be lean but they get pretty hot at the best of times.

I ran into the same situation today but it only happened while I was revving it up a bit. Once I let it idle it went back to normal. Too lean??? I'm not sure.

just dont stick your tounge on it, it could blister :banana:

My 426 will look like a cherry bomb in the sunset. I have about 600 miles of nothing but shooting roost with her, and she is running very well. I havent statered it in the dark lately but when i did it looked like a molten piece of steel. I have sence did some mods to her and havnt started it at night, but can tell you with confidence that this pipe will glow very very very red.

If it becomes brighter than the sun in the day, you might have a problem, other wise I would just roast some marsh mellows over it :ride:

Probably a little lean. Mine did the same before rejetting.

Too lean for sure. It will glow red for a few inches while idleing, but it should only be red near the head when riding. If it is turining red while riding then cooling off while idleing it is lean for sure. Re-jet it.

When I first start my YZ 450 and am in the garage(dim lighting) it will glow red as you described.

I'm not sure if it does this while riding or not, always in bright, outside light.

It is bone stock so I haven't worried about it.


You always need to jet for exhaust that flows more freely, you will probably notice less low to mid pull as well :prof: Just try a richer main or look in the jetting forum, do a search for Indy's chart :applause: . Normally the header will glow if not enough heat transfer is taking place, i.e., sitting still but you are prime candidate for being too lean....... It's easy to swap out a main :D

I have not seen a stock bike regardless of brand that was not a little lean. The KTM's seem to be the worst, but Yamaha is pretty lean also. My WR was glowing red within a inch or two of the muffler junction stock. I would guess if your header is glowing past the bend you are too lean. It all depends on elevation, temp, air flow, etc.. There is no one perfect set up for everyone. I prefer slightly rich over lean, but your throttle response will not be quite as crisp. I think over the long run your motor will last longer due to running a little cooler.

Mechanic at the dealership told me it would do that as he was loading on the trailer for the trip home. Nothing to worry about, it's titanium, and it's perfectly normal. I'm helicopter mechanic, and titanium is used extensively in the jet exhausts for lightness. It's always glowing red.

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