ok so i got my 400ex running again, i replaced the plug and it fired right up. but as we revved it and kept it idleing and revved it i look down and my headers are GLOWING red. is this normal? if its not normal what is it?

 

It is air cooled, so if no air passes over the header (like when you sit idling), things heat up!

If your header was red hot while riding at speed, then we might suspect that you are running pretty lean, but sitting at idle I don't think you could expect anything except for things to get real hot......

 

ok, i was sitting but it was only on for like..2 minutes?

i still havent replaced the timing chain, [on order] could this be caused by the timing being off?
ive heard that from my dad's friend, he is a mechanic.

 

yes! you either have the wrong plug in it or your timing is deffo off.
if it has 2 cylinders make sure that the plug leads are on the right ones

 

..i just put new plugs in it.

hmm.. but i know i need a new timing chain.

so we will do that and see how that goes first.

thanks.

 

my old 400ex did that. i cleaned the carb mainly the choke area and it never did it again. i could sit there for hours with it jus idling it would never get red.

 

if its running lean the header will "over heat", more than normal temp. like glowing red. its probable just the pilot or slow jet....thourogh carb cleaning

 

i very well may be wrong but i thought headers got red from being to rich. my neighbors old street bike did that and he told me it did it because the choke was stuck open. that means its gettin to much gas and burnin hot. i need help with this one too!!!!!!!

 

<div class="FTQUOTE"><begin quote>Originally posted by: go-hard-or-go-home

i very well may be wrong but i thought headers got red from being to rich. my neighbors old street bike did that and he told me it did it because the choke was stuck open. that means its gettin to much gas and burnin hot. i need help with this one too!!!!!!!</end quote></div>

Not sure how the choke being stuck open would cause an engine to run hot. That makes no sense. There had to have been another reason why it was running hot.

Generally speaking a lean condition will cause the engine to run hot...... what most people don't really think about is that gas actually cools the piston. If that piston is being starved for gas it is not getting the proper cooling as their is less cool gas being introduced to the combustion process.

This is especially noticed on an air cooled engine, as there is no external cooling system to help keep that piston cool. And when the piston is too hot, the entire engine is too hot, and the expelled gasses going through the header and exhaust are too hot. So that header will light up like the sun if those expelled gasses are too hot.

 

nevermind.