My header heated up to 536 degrees in 5 minutes.. ***??

[SOCAL90]

Hello everyone.. I need some help.

Any of you have a clue why my head pipe would get so hot that it started cooking my carbon heat guard in about 5 minutes? I checked the temp and it was 536 degrees!

My set up is: 08 yz450..Akra evo full system, JD Jet kit.. stock motor

The bike has been sitting for about a year (had back surgery) and the ONLY thing wrong with it is the Akra can is a little bent due to a crash I had last year.

When the header was over 500 degrees the can only tested at 170, the cylinder head was about the same..

Any ideas? ?

[gscx]

Thats it? I thought they got alot hotter than that

[woods-rider]

When motors are lean they can run hot. Try richening it up a bit.

[gscx]

If its running fine then there isnt any need for it. They will get so hot they glow if you let them sit and idle

[SOCAL90]

I've never had my carbon literally burn and smoke.. it bubbled the akra logo right off..

I will check how lean it is though, thanks

[ttr250dude]

Thats it? I thought they got alot hotter than that

? nice

No offense but, use the search button. DO NOT richen your A/F ratio if your bike runs good. That will not solve the problem. The problem is that you let it sit and idle for 5 minutes.. If you let these bikes sit for more than 1 minute the header starts glowing red. These bikes need air flow. If your bike is already at running temp dont let it sit and run for more than 1 minute or else it will start heating up alot. They are known to over heat even when in slow 1st gear single track.

[grayracer513]

Thats it? I thought they got alot hotter than that

They do. Red heat visible in twilight is around 880.

More often than not, a rich idle will make the header hot faster than a lean one, and you can't expect the bike to sit and idle for 5 minutes. That becomes a race to see whether the radiator will boil over before the header turns orange.

Revving the engine frequently to pump cold air through the system will reduce the effect, but it's better just to keep moving.

[Gunner354]

When motors are lean they can run hot. Try richening it up a bit.

This is not only wrong but very bad advise.

[RiderX]

This is not only wrong but very bad advise.

Not necessarily.

[Gunner354]

Not necessarily.

Really? Please explain with solid facts.

[RiderX]

Really? Please explain with solid facts.

A lean fuel mixture can cause higher combustion temps and EGT's.

[Gunner354]

Let's get back on track here. Suggesting richening up jetting based on a presumed lean condition due to a presumed abnormal exhaust pipe temp is just beyond me and very bad advise.

[SOCAL90]

They do. Red heat visible in twilight is around 880.

More often than not, a rich idle will make the header hot faster than a lean one, and you can't expect the bike to sit and idle for 5 minutes. That becomes a race to see whether the radiator will boil over before the header turns orange.

Revving the engine frequently to pump cold air through the system will reduce the effect, but it's better just to keep moving.

Thanks everyone for the reply's... I guess I should have mentioned that I didn't let it idle for 5 minutes. I used the choke on idle until I could turn it off, then I blipped the throttle a number of times (I am under the impression that the water pump only spins if the motor is revving.. is that correct?) I started to see smoke coming off of the header, which I assumed was probably just dust burning off or something. But, the smoke increased rapidly. That was when I realized it was the carbon fiber heat guard that was actually burning. Which made me check the temp because that has never happened and I assumed it was too hot if the "heat guard" was literally melting. That's where my main concern came from. Do you think maybe the carbon has deteriorated or something and that's why it started to burn?

[grayracer513]

I am under the impression that the water pump only spins if the motor is revving.. is that correct?

No. It's geared to the engine, so if one turns, so does the other. They don't move very much water at an idle, though. Then again, the radiators don't do much without air flowing over them anyway.

[ttr250dude]

What we're trying to say is that you shouldnt let the bike sit stationary with the engine running for that long. It doesnt matter if you let it idle or blip the throttle. The problem is that air is not passing through the radiators. The only reason cars can sit and idle for a long time is because of the fans that pull air through the radiator when the coolant reaches a certain temp.