i purchased a 2002 400ex wich had very little use. i went to go ride it tonight and started it up, took a lap around the yard and went back to the garage and noticed the exhaust pipe was glowing red right where it connects to the cylinder, the 4 wheeler is all stock and i just changed the oil a week ago. i also changed the spark plug, i would really apprectiate any help as i have no idea as to what is causing this. could the spark plug be wrong? i really don't know please help

 

i think its normal...cuz in my friends cars when we drive around at night then pop the hoods cuz we been drivin for a long time there glowin red but its jsut cuz theres no light on it...ride it the same amount at night then do the same in the day but in the day jsut go in ur garage and turn the lights off and it will be the same its with all motors well at least mine

 

sounds like a jetting issue to me... your running lean

 

like i said i bought it and it had very little use when i bought it. it had been sitting in a garage for a year to a year and a half and never got started, so maybe one of the jets is plugged does that sound right? thanks for the help

 

no not plugged... if it runs really well then the jets are fine. have you change the gas and oil sence you bought it. if that all checks out u just need to rejet nothing major

 

yes i have changed the oil and have ran 1 tank of gas through it

 

i just went out n rode mine n mine does it to and i jstu got it back form the dealer like 2 days ago so there prolly isnt anythign wrong with mine so its prolly jstu normal

 

I say you're running lean, also. Do a plug chop to verify this. If you don't know how, get a new plug, put it in and run the quad at full throttle, then kill it, at full throttle. Pull the plug, it should be a tan/caramel color. I'm guessing that yours will be white because of the lean setting. Change your main jet up a size or two and it should solve the problem. Please note that this only works for your main jet, not the pilot.

 

I've seen several different models of ATV's do this. Most noticable when they sit and idle, especially if the idle is too high, or at an extremely fast idle as in choke on partway. Not just Honda's either. Yesterday I worked on a BRP Outlander. It was very cold here,
like -5F at the time, so I let it run on partial choke outside to warm up. It was idling quite fast. About 5 - 10 minutes later I walked out and the head pipe looked like somebody had an oxy torch on it.

 

thanks for all the help i just bot a new jet and am going to try it out