I have a 2001 400ex, with a wb e pipe, aluminum airbox, twinair filter. I live in michigan. I need to adjust the needle in the carb but i can't figure out how to get to it. I have changed the main jet to a 152. I have also seen the adjustment on the screw that holds the main jet. But i can't figure out how to adjust the needle. What is the stock position, and what would i need to goto. It sputters on the low end, and wants to stall when you slam the gas. It fouls plugs like crazy. If you could help me out it would be greatly appreciated.

 

what size pilot jet you running? where is the fuel skrew set at?

you have to get to the needle from the top of the carb. you will first take the 3 skrews out of the top. be able to get to the needle from the top. there will be two skrews holding the slide down. you will need to remove the slide. also, you may need to remove the one skrew holding the slide arm down. when you remove this skrew, the slide won't be spring loaded. in order to get that one skrew back in you will want to take off the right black plastic side of the carb and push the lever in to make the skrew and skrew hole to line up.


the piece that hold the mainjet in place is the needle jet holder. be cautious when removing that because there is a little jet above this that looks like a tic tac. it can fall out if your not careful. also, when you set the needle jet hold back into place you will notice that a nut is what tightens it down. the adjustment on this is important for best performance. you will want to tighten the nut down so that you see 3-4 threads on the needle jet holder when the nut is tightened down. do NOT tighten the needle jet holder all the way in. your performance will decrease.


the stock needle clip will be in the 3rd position. move it down to the 4th position and you should be good to go.

good luck