My 99 400ex(all stock except for a K&N air filter) will not idle(when its cool outside) until it is fully warmed up. This means I have to sit there and keep the RPM's up for 10 minutes! Also, wants it is warmed, everyonce in a while when I let off the gas it will sputter and if I don't catch it fast enough it will die. How can I fix this? Thanks

[This message has been edited by neff.79 (edited 01-03-2000).]

 

I went to a #50 pilot jet and set the air screw at 1 and 1/2 turns out. This seemed to fix the problem which is lean jetting from factory. See the previous thread "Pilot Jet on 400ex?" for a detailed description.

 

Thanks, any other tips?

 

So what is the stock pilot jet size in the 400EX?

 

Stock pilot should be a 38.

 

I think it was rooster who said this first, but make sure your throtle cable is adjusted right, i rode about for 4 months only going to about 90% of full throtle. Sure had a lot of problem setting up my main jet until i seen that...

 

Sickyl,

Did you adjust your throttle at the handle bars or did you have to open the carb? I noticed mine had two much play so I adjusted at the handlebar but haven't had the opportunity to fully test it out at the track.

 

I found out about the throtle cable as i was converting to a twist throtle. I had the black plastic plate off the side of the carb. I noticed that if I pushed the thumb throtle all the way open, I could then open the carb more with my fingers. The shop manual say that the thumb throtle should have 3 to 8 mm of play at the end, and it is adjusted at the handle bars. I am not sure if you can easily find out if you are going full throtle without removing the black plastic plate... I am sure some one here knows a way