I need help Rejetting my 2003 400ex

[LBo]

Hello I am new and I need help rejetting my 2003 400ex. I rode the bike completely stock since I got it about 6 months ago. Just recently I started adding some aftermarket parts. I put on a lexx slip on exhaust, a velocity air filter w/outterware, a k&n power lid,a aftermarket cdi, a bigger coil. Now the bike is running bad it's popping and spudering and doesn't seen to have the hole shot it once had. I live in the most southern part of Louisiana and we have very mild winters and very hot summers and I am below sea-level. Any help would be great. Thanks

[JOHNDOE83]

Popping and backfiring on decel is from the pilot jet being to small, you deff need a bigger pilot and a bigger main jet.

The best way to jet for a main jet is to buy jets in incriments of 5 in large sizes from 200 down to 160.

Start at around 190 if it sputters on the top end and doesnt fully rev out drop down sizes in incriments of 5 till it fully revs out.

You'll need a 42 pilot jet and turn your a/f screw to about 2.5 turns.

read the faq section here www.jetsrus.com and also buy jets from here.