My 400 cuts out alot. I thought it was jetting riding at 9500ft but when I dropped it it still does it. Only does it after it has ran for about a minute. Is it a possible fuel filter issue or does my clip need to be raised? It does it at 4400ft as well but not as bad. Plug check is good too.

 

Mine does it when you first start it up and keeps missing and sputtering for about 1 minute until the motor heats up then it runs fine.

 

yeah its just not warmed up

 

altitude is EVERYTHING to jetting. I live in Utah and my 400ex runs like crap if I go up ONLY 2000 feet. So if you are changing 4000 feet- I'm not suprised you ran into problems. I have found that raising the idle speed helps (a little).

** and for you, flattrack- You should try raising your idle speed- Once I push my start button, it purrs like a kitten and never stalls out. But when the engine finally warms up- I drop the idle speed back down.

 

It cuts out bad at low speeds in the higher elevations. Down here in the valley it only has a slight miss. Its like it is starved for fuel. I'm also thinking a possible fuel filter clog? (i've never had to change a fuel filter on a atv)

 

...I'm telling you- it's your HIGH ALTITUDE- and rapid change.

The only real fix is to change your jetting- but that's difficult to do on the trail. If someone were to make a "dial-a-jet" that you can adjust on the go. They have those for other applications- like R/C cars.

 

<< It cuts out bad at low speeds in the higher elevations. Down here in the valley it only has a slight miss. Its like it is starved for fuel. I'm also thinking a possible fuel filter clog? (i've never had to change a fuel filter on a atv) >>



You've never had to change a filter because there isnt one.

Play with the jetting more, that is your problem. They do make dial-a-jets for ATV and dirtbikes, but not sure if they make it for the 400. Dennis Kirk catalog used to stock them.

 

there is a filter in the petcock. a very very little one. i took mine apart one time and found all kinds of junk in my filter. but my bikes 15 years old and id say thats the only time someones looked at it. it didnt make much of a change at all after i cleaned it except it leaked gas like crazy. i agree it ur jetting. i dont know much about it but it makes sense that if u go from real high to real low real fast that it will run differently. settin ur idler screw in a little should fix it like RotGutBottom said.