I have a 400EX right now i havent change the stock jet but i need to it back fire and doesnt seem to have the power it should.I live in Ohio I will be going to the K & N air filter soon right now it stock any info would be great

 

My buddy is running a 155 main and 40 pilot. We live in Iowa. He has the Powercore IV2 but not the powerbomb (yet)

 

I've been looking at this pipe for my 2000 400EX, as well as the Supertrapp IDS2. How loud is the Power Core IV2 compared to the stock pipe? Notice any HP gain?

 

alot louder but a deep sound so not to bad nothing like a 2 stroke dirtbike ....yes i have alot of power gains but im still using stovk jets once i change them i should see more i only have the pipe i stay with the stock headers..........

 

Hey Lucis, have you taken a plug reading yet? If not that is the first on the list. The k&n will definitly lean the jetting out so you will probaly have to go up on the jet size. IF you get it really close with the jet then adjust the needle as nessisary and that should do it. Hey let me know how it turns out I'm looking at that pipe or a procircuit.