when i put a k@n air filter on do i need to rejet

THANKS FOR YOUR INPUT 400EXCRAZY

 

If you mod. your air box you will.

 

Any increase in air flow requires a re-jet.

 

Yes. If you don't have to rejet, you didn't improve a thing! All you did way spend your money.

 

yeah you should have to.. i would suggest it.

 

yes but probably not much.

 

I picked up one with prefilter for wifes 250ex. Anyone have experience with this. I figured I'd have to rejet just wondering if anyone has with a stock 250ex. thanks

 

Somewhat related. I put a White Bros. exhaust on my wifes 300ex and I had to rejet from a 122 to about 128. I then added a K&N filter and removed the lid, and now the jet is a 142 and it is still a little lean. The bike also really came alive.

 

little mods like that should require a lot of jet, but definately some rejetting...that is what i liked on my last sport was that i had a "dial-a-jet" system on it and it was really easy to dial it in to run just perfect.

 

may as well throw a slip on exhaust on while your at it,,,,to give yourself a real reason to re-jet

more air, more fuel, more flow.....