i am going to put a k and n air filter on a 400ex and on a 300 4x4. would i need to rejet either or both of these atv's with this new filter. i am not adding a pipe or anything else. do u recommend this filter or another brand. thanks!!

 

Being that you plan on doing nothing else but changing the airfilter, I wouldn't go with the K&N.

Every bike responds to changes differently even when you have the same machine. Your TRX300 might need a jetting change with a K&N and then maybe your buddies wouldn't.

Go with a Twin Air filter or another brand quality "dual stage" FOAM filter. Everyone is too quick to jump in there and put a K&N filter on there when the Twin Air flows just as well and filtrates just as well if not better.

The majority of all the pros whether it be Cross Country or MotoCross run Twin Airs or Unis more than they do K&Ns. Just a thought.

KNOWSALOT

 

I doubt they flow the same because if they flowed the same then you would need to rejet for both not just the K&N. My 2 cents

 

Very true killer250R , but I wasn't recommending the dual stage foam over the K&N based simply on ease of jetting. Just that alot of them flow as well as the K&N and more times than not, filter the dirt better.

KNOWSALOT

 

Yes i would also shy away from the k&n unless you use an outerwears
I dont think you will need to rejet because you havnt done any exhaust
so you are push more air in but not takin any out.