im going to be running a k&n with prefilter and no air box lid, what should i do for jetting for a K&N filter on 250ex? im going to run a K&N with a prefilter and no airbox lid, so what should i do for the jetting?

 

try the k&n jets, would be a great mix with the k&n filter

 

That little engine can only handle a limited amount of air. It's only a 250 after all. With a K&N and the lid off, I think you are going to have to much air. I run a UNI foam filter, lid on, and a couple of UNI vents in the lid.