2003 trx 400es missing at idle

[downhillv10]

Hey everyone! I just bought a trx 400es It spent most of its life in a garage and I got a killer deal on it It has a slip on DG muffler and a foam air filter and all air box lid and snorkel is in place here is my problem! When I'm going up thru the gears and pulling hills it has a ton of power but at idle it has a miss and when I'm going downhill throttle off. when I put the choke on half way at idle it goes away but loads up,now I live at 5600ft and the quad came from 3200ft and I'm thinking its running lean, maybe changing to a bigger pilot jet? I also lifted the needle up to the last groove and it pulls real hard(crazy fun!!) so and Ideas this is my first quad but I do have pit bikes and had to change to bigger jets to get them to run right! so any advice on things to look for on these models would be helpful too! Thanks!!

Tearing it up in Yellowstone country!:cool:

[DragonGunner]

Your pilot jet could be dirty.....try turning your idle up a little, sounds like its set too low.

[Stickman400]

Also might try turning your air fuel mixture screw in or out 1/2 a turn and see if that makes a difference.