Is anyone currently using a 400EX with the following mods:

Air Box Lid Off
K&N Filter
170 Main Jet
40 Pilot Jet

If so what do you think, If not how are you running it and what are your thoughts?

 

I had that set-up. The main sounds a little high but you may be at a higher altitude. The 40 pilot helps starts and idling. I got the set-up from Lauren Duncan of Duncan Racing, so it is credible. He is sending my motor back to me today with their 440 national kit so I'm sure my jetting will change.