400ex cutting in and out

[toofidyare81]

i have a 2000 400ex.....and when i hold it when i hold it wide open it just cuts in and out......does anyone have any suggestions>?< thanks

[2004exrider]

Main jet problem. Check your spark plug for the color, if its black your main is to rich, if its white in color your to lean. These problems can easily be fixed by swapping in different jets until it runs fine.

Jimmy

[bwamos]

Sounds like you're too lean on top. Some rev limiters can make it cut out too, but odds are it's jetting.

Being you have a 250r, I'm not much more help. Minimal 2-stroke experience.

[key4202003]

sounds like your starving for gas. check float level. or maybe you gas tank vent line is pluged.

[toofidyare81]

thanks ill check out the jetting

[toofidyare81]

i checked the spark plug at its black. so its obviously running rich....do u think that could make it cut in and out? and if so wat jet is the top end? i think its the pilot jet but im not sure and if it is how many sizes should i go up or down?

[2muchquad]

if it just started doing it then i wounldnt say its the jetting.make sure your air filter is clean and not over oiled.make sure your vent lines arent twisted and try a new plug.if it still shows the same symptoms i would inspect the coil and the plug wire.i have seen faulty coils make the bike not want to rev out and pop like its too lean.you'll just have to eliminate the possibilites one by one until you find the culprit.i dont think anybody on here knows your problem without seeing the bike personally.sorry:(

[2004exrider]

The main jet controls 3/4 - full throttle. Since its rich, go down a jet size or two. To change it, look on the bottom of your carb there is a 17mm cap remove it. Inside there is a 6mm jet take out and replace with your different jet. Your 400EX will be running better.

Jimmy

[toofidyare81]

thanks ill try that