Yes that was, and yes he has a problem. Maybe bad exhaust manifold, maybe too small of a low end jet, maybe heading for burned valves. Ask another mechanic at the same shop or perhaps the manager

 

had this happen on my 300. my head pipe cracked and cool air got in and makes the exh burn very hot. this can melt down an exh valve fast. if it is cracked you should here a clicking or hissing sound every time the exh valve opens on the stoke. i could feel the exh leaking with my hand but only try that if the engine is completely cool before you start it will warm up fast, dont burn your hand. the trick of carb cleaner will work for intake leaks but i have never tried it with exh leaks
good luck
seth tynes

 

That depends on the color. Bright cherry red or salmon and your literally playing with fire!!! A piston will start to get soft at a little over 1,500F (EGT). 1,600 and over, and you done.

Faint Red 930

Blood Red 1075

Dark Cherry 1175

Medium Cherry 1275

Cherry 1375

Bright Cherry 1450

Salmon 1550

Dark Orange 1630

You make the call at what color the pipe was. I set my EGT at 1,350 to 1,400F. I have run as high as 1,500 for a few seconds at a time but I don't recomend it; especially with a light racing piston. I don't like to see any color on my pipe, no matter how thin it is; that's just me though. Lean is mean, but I see no sence in pushing it.

 

i don't call that BS by any means. the stock 450r's that i have seen do this too. here's whats going on. your giving it a bit of gas, the pipe glows. you just a bit lean on the needle. i think your getting confused on lean and rich conditions. rich is where the bike would run cooler and lean it would run hot in most conditions. rich is too much fuel where lean is a lack of fuel. well, you said the pipe quits glowing when you let off the gas. at idle, the pilot jet/fuel screw are primarily being used. so, since the headers are not glowing at idle, your fuel screw position much not be lean (which is a good thing). when giving it gas, the needle assembly is primarily being used (below 3/4 throttle that is). is it getting cold where you live?? if so, i would just lower the needle clip position and your problem should completly go away or greatly diminish. the stock headers on the 400ex are stainless. the glowing with stainless headers is more likely to happen. if you ceramic coat them, you may not notice it as much for example. i would say if your in cooler temps, just lower the needle clip position and you will be fine. the jetting changes pretty drastically from summer to winter. in the winter the cold, dense air has more available oxygen. this means you need to richen the carb up. if your getting more air, you need to give it more fuel.

 

I had this problem also. My problem was the gas was old in the bike, and had a hole in exhaust on the right side where the gaurd is. THis was on a stock, then I put a after market on, BIG GUN and it was not jetted right. SO check your jetting and a hole in the exhuast. I never seen the exhuast do this except for these two times.

 

cals400ex has the best answer here.

 

thats right i do.

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i have jetted 400ex's enough to know by now. my sparks pipe did the same thing.

 

Thats normal don't be alarmed won't hurt anything, if it does at idle that check mixture setting ride on