What jetting for pro-circuit t-4 with k&n air filter

[Stevo]

I got a procirut t4 slip on for my 400ex. I have the stock jetting now, i plan on getting a K&N filter for it. Anyone know what the best jetting would be to use. I live in johnstown, pa area???

[300exTJjeeper]

I got a 300ex witht he T4 with Uni and it's jetted but for yours I think most people run with 162 main and 42 pilot that will be good starting point for ya then do your plug checks.

[[_4ex_]]

i run this slip on and i run a 160 main jet (dyno jet)

,itsthe size could depend depend wich jet you use,

just rejet it and look at your plug

[sly400ex]

I've have a 160 mj and a 42 pj. No air box lid and a K&N. It runs awesome right now, but when it gets a little warmer, I think I will go down to a 158. It's about 20-30 degrees here too.;)

[Extremeracer167]

I setup a few quads with the same setup(not far from you) kittanning PA, they LOVED the 158 main with some mods to the airbox lid.