exhuast turned wierd color(300ex)

[thursday]

the exhuast turned like orange red up by the header idk what is worng i have a sparks exhuast and it has never done this before

[Out_Sider]

mine does that when it just sits there and idles..mine is a dmc tho, but there both stainless. It might be from the engine getting to hot, from sitting or your jetting is a little lean..my jetting is a little rich, but let it sit in one spot and idle for too long..sucks cranking somin up and get it warmed up then go take about a 5 minutes pee and come back and my pipe is red :mad: LOL!

[thursday]

well rite now im running a 135 main jet u think i should go up to a 140 main jet

i really need help thanks fella's

[Out_Sider]

yea, just to be on the safe side i would put a 140 in. Im runnin a 155 in a 400ex carb, and 45 pilot...so its rich at idle..but it does good for cold starting.

[UglyMotha™]

a glowing header is normal mine is really noticable at night

[2004TRX450R]

yup it is normal to glow when sitting at idle as there is no air moveing across it to cool it. Changing the main jet won't help at all because it is only used at 3/4-full throttle. It isn't even being used at idle. You would need to adjust your pilot screw or change the pilot jet. But like I said it is normal to glow like that. Try adjusting the pilot screw to the point that it raises the idle the most when the engine is up to operateing temp. That will be the place it needs to be.

[Colby@C&DRacing]

That is not really normal only if you are running lean riching that thing up:)

[cals400ex]

i agree, i would turn the fuel skrew out if it only does it at idle. if it does it between giving it very little gas(around 1/8 throttle) to 3/4 throttle, i would move the clip on the needle down to the 4th position. the 400ex needles seem to be pretty lean in the 3rd position during the colder months.

[2004TRX450R]

I haven't really seen it on the 300EXs with stock exhaust but on the 400EX stock or aftermarket exhaust and on a lot of the new 4 stroke MX bikes I have seen it a lot. It is common for it to do that when sitting stationary not moveing.

[thursday]

welp today i was riding and it started to glow it glows while im riding and ideling whats up with that i went in jetting to richer cuz its cold

[Wingman]

i would agree with the others you are runing a little on the lean side. usually it won't run right till you get the fuel air mix were it should be. get it running good in a heated shop then just turn your idel up a bit for the cold.