I was riding my new 400EX in at night for the first time last night. After about 10 min. I noticed that both exhaust head pipes were glowing red. Is this normal or should I be worried ?? The bike only has about 25 hrs. Please help.

 

that means your pipes are getting really hot which comes from your engine running to lean. If its running to lean your engine will overheat and if you don't fix the problem you might need a new piston installed do to your engine blowing up. If it doesn't over heat it should be ok. The leaner a machine runs the more power. To lean is bad

 

Thank's for your help. I'll check the mixture and try it again.

 

dude, that happens with most 400ex's..... they all run a little lean..... mine did it and all my buddies did it too...there is nuthing to worry about... the only reason it does that is cause the wallls of the piping are very thin... thats what makes them good... dont worry about it.. al 400EX's run lean.

01 400EX Yellow

 

Thanks, but you mentioned the word "MOST 400s" can you be a little more specific. Is this normal or not? The thing seems to be running good and does not smell hot or feel hotter than most air cooled 4 stroke motorcycles that I have had in the past. I am going to take a look at the plug to see if it looks normal. Do you know how to check if you are too lean? Anything that I should check? Most 400s I have looked at did have "purple-ish" color on the head pipes.

 

THE SAME THING HAPPENED TO MY 440EX HEADPIPES,BUT I HAVE A WHITE BROS. PRO-MEG EXHAUST SYSTEM,NOT STOCK. TO FIX THE PROBLEM I PUT IN A 40 PILOT JET AND MOVED THE CLIP ON THE NEEDLE DOWN TO THE 4TH NOTCH. THIS SOLVED THE PROBLEM IT ALSO HELPED WITH HARD STARTING WHEN COLD. HARDLY HAVE TO USE THE CHOKE ANYMORE.

 

if the plug is grey/white then the engine is running lean. if the plug is blackish then the engine is running rich. i heard it is better to a little rich then lean. lean will cause an engine to sieze up.

 

Try oppening athe idle jet up about 1/8-1/4 turn at a time. this will richen it up a little, and backs down the heat a little. If you are in a cold weather climate, it will naturally run leaner withe the air density change. I opended all my buddys and my 400 up a little, and they start alot easier in the cold. just remember to close it back up when the weather warms back up, or else will you will be lacking in performance from being too rich. good luck.