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400ex problems
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Posted by: DGA

I've searched and searched and searched.

I have a 2001 400EX it is stock except for a uni filter and full Yoshi rs3 exhaust with airbox lid off.

I live at 1000ft alt. it is approx 80-90 degrees and 85% humidity.

Im running a 152 main, 42 pilot jet, needle 3rd clip position from the top and 1.5 turns out on the fuel screw.

In midrange the bike pops on decelleration and spits some flames occasionally. Bottom end seems decent. If i go to 1.75 or 2 turns out on the fuel screw it seems to be too rich and hard to start. It seems like maybe my needle clip position is too rich mayber? I dunno. What was the stock position? Someone help please.

Also I removed the choke.

Posted by: 400exrider707

try going to a 40 pilot and then 2 1/2 turns out, and maybe a 155 main.

Posted by: kyex40047

If it runs good on the bottem end, then your fuel screw and pilot jet are fine. Mid range is your needle, and top end is your main jet. Try raising you clip, or lowering it, Sounds like your problem is in the needle. How dose it run in the mid range? Does it pull good.