Which filter would you use on a 400EX? I am going to get my bike jetted and I hear the old stand by K&N is the best. Then again, I heard Uni foam air filters work better for all around riding?

Uni?
or
K&N?

Thanks

 

Forget it guys. I searched the forums like I should have before posting. I got alot of good info from past posts. If you would like to add some comments I would welcome them.

Thanks

 

i really don't think it matters too much. i have a twin air filter. it is a little smaller than the stock one so you have a little more room to work with when installing the filter. which that doesn't matter to me. uni should be similar to the stock one and twin air in the performance category. the k and n will flow the best. my friend has one and it doesn't stop the tiny dust particles like my foam filter does. i perfer the foam for this reason. although many people run the k and n without any trouble at all. if i was doing it i would be getting uni. my friend has a k and n with a pipe and jetted. i have a twin air, uni air vents in the airbox lid to flow more air, and i gutted my stock exhaust. in a race he does't even beat me. he does have a little more torque with the pipe but i also have a bigger front sprocket and that may be why also. in a drag race we are pretty much dead even and many times i happen to win. the uni will be about half the cost. you can put the vents in your lid to make up for the airflow differences. its pretty weird how he paid $270 for a slip-on silencer, around $50 for the k and n, about $10 for the outerwear, and then whatever the new jet cost him. i paid $25 for the twin air filter, $10 for the uni air vents, and then i also rejetted so the cost of the jets. i did gut out my stock pipe but that was free. as you can see he spend around $300 more than me and we are around the same speed. i usually am faster too. if your stock filter is in good shape i would not spend the money on a new one. you can drill a few holes in your lid and even put the uni airvents in there if you don't want all kinds of dirt in there and run the stock filter. i would probally go up on the main jet from the stock 148 to a 150 or so with holes in your lid if you don't have a pipe. you should probally be set then.

 

Cool, thanks for the info and your opinion. I ended up getting a UNI and I am happy with it so far. I enjoyed reading your comparison also.

 

click here - K&N vs UNI

 

That was a good link Bandit. Thank you, had some good info to think about!

 

I found this interesting from CT racing.

CT Racing