Hello I am new on here. I am looking to get a good idea on where to jet this newly rebuilt 400ex. Its a 2000 and it was stock before, I just put a 20 over Wiseco one step higher compression piston in it, stage 1 Hot Cam, a slip on Cobra Jet exhaust, and a Uni air filter and I am going to run it without the air box lid. What would be the pilot and main jet sizes to work good on this combo and needle clip position. Any help would be great Thanks.

 

honestly every bike reacts differently to jet sizes. but ive pretty much got the same set up as you. im running a 160 main, clip down one and a 42 pilot w/ choke removed. you wont need the choke at all with a 42 pilot which will clear the carb throat a little. also i kept my lid and just drilled some holes. i think way to much dirt gets in with the lid off unless you ride dessert only.

 

im happy with my 190.