I was warming up my 400ex and when i reached down to turn off the choke i noticed the header pipes glowing red, not just a slight tint, but really red. Is this normal?

 

were you in the dark or were you in conditions with lighting? Either way, i am stumped on what is happening.

 

I have never seen this, but I would imagine if you are sitting for a while and there is no air passing over the engine, the pipe could get red hot pretty fast. Does your bike have stock jetting?? Stock jetting is on the lean side (to meet emissions), which can make a motor run hot. On the other hand, if it happens while you are riding, I would check to be sure you are not running extremely lean.

 

The materials in the stock pipe pass heat extreemly well...this is normal for many of the new four-strokes with stainless head pipes...seen it on anything from DS, Raptor, CRF450, take a plug reading to assure that you arn't to lean at an idle.

braaap!

 

I was sitting still in a dark shed. Not completely dark though. When I pulled out in the driveway I couldnt see it anymore. Jetting is stock. It only gets red when im reving up, not when its idleing.

 

Perfectly normal.

Mine does the same thing except it is a 300 with a DG pipe and header. Only glows if I am reving it up in nuetral and keeping it there for like 20 seconds.

 

I guess i will try this on my 300ex tommorow. It is completley stock but it might still happen. I'll update you on what happens.

 

The stock head pipe is single-walled, and will get hot and glow when left to idle. Mine did the same thing when I bought it new. After fattening up the jetting, it never happened again. A motor that is running lean will run hot.....enough said.

 

it should be normal........