Hello to all, need help on my new quad...

[rockrat46]

I just got into quads a few months ago and I picked up an'02 400ex. I was just looking for some info on air filters and whether or not the K&N is worth the money? Would I have to re-jet? if so what do you all recomend? A friend of mine pointed me in the direction of this site. There is so much information! :eek2: thanks for any responses and hope to get tons of info from you guys!!!

[Moto49X]

If you ride in any sort of dust, i would highly reccomend a foam style filter over a cotton. From my expierence K&N allows alot of dirt to flow through. I run Uni filters, just use alot of oil on them. Also, if this is the only modification then there is no need to rejet, it will be fine untill you get into more mods, IE: Exhaust, motor work.

[Kickstarts-suck]

Check out UNI filters

no you wont need to rejet

[honda300EXtreme]

a k&n with a pre-filter will filter just as well as any foam filter and im willing to bet it flows more air,,

if you air box is not vented,, you wont need to rejet,, but if it is well vented you may experience some poping on deceleration,, so you may have to back out your air/fuel screw

welcome to the site

you will need to rejet with any combination of air filter/ aftermarket exhuast. anytime you let more air flow into, or out of the carb/motor, you need to even that out with more fuel. the air/fuel mixture needs to maintain the same ratio. if you don't you will be running lean and that can be very bad for the motor.

[rockrat46]

thanks alot for the quick responses, guys. I forgot to mention that the previous owner put a white brothers exhaust on the quad already. I wanted a louder sound so i took out the baffles/fins at the end of the pipe. It starts ok, though the beach drained my battery from trying to start it, but overall it did very well.
i am leaning toward the uni due to cost. I really appreciate the info, the more the merrier! thanks fellas, great site.

[steve181]

no K&N is a very bad air filter

id go with a uni ari filter

NOTE: if ur gunna use the K&N use a outterwears cover for it

K&N lets 2 much **** in

[400exrider707]

Originally posted by honda300EXtreme
a k&n with a pre-filter will filter just as well as any foam filter and im willing to bet it flows more air,,

if you air box is not vented,, you wont need to rejet,, but if it is well vented you may experience some poping on deceleration,, so you may have to back out your air/fuel screw

welcome to the site

How exactly will a filter let more air in but less dirt? Especially since the K&N are physically smaller.

Only two ways to get more air in... bigger holes, or a bigger filter. UNI's are a bigger filter.

Hold one of each up to light. You can see light shining through a K&N filter.



Try searching this topic, you will find lots of info.

[NacsMXer]

Originally posted by honda300EXtreme
a k&n with a pre-filter will filter just as well as any foam filter and im willing to bet it flows more air,,

if you air box is not vented,, you wont need to rejet,, but if it is well vented you may experience some poping on deceleration,, so you may have to back out your air/fuel screw

welcome to the site

Prefilters/Outerwears/etc. don't do squat to filter out harmful dust particles, the pores are much too large to accomplish that task. Their purpose is to provide water resistance and to prevent larger dirt particles from prematurely clogging the filter.

I used to run that same filter combo on my 400: K&N+Outerwears and another Outerwears on my airbox. I now run a UNI foam filter and an Outerwears on the airbox, and I am convinced that foam hands-down filters better than the cotton-gauze media found in K&N's. The proof was in the amount of fine grit the K&N allowed into my intake boot; with the UNI I found none. Switching between the two filter types in the same riding conditions, I hardly find this to be a mere coincidence :o

[yfzrider45]

My OPINION is k&n is always worth the money. i've been runnin it since 05 and i'd never go back to a foamie. BTW i ride a yfz...

[Moto49X]

Originally posted by yfzrider45
My OPINION is k&n is always worth the money. i've been runnin it since 05 and i'd never go back to a foamie. BTW i ride a yfz...

If you run a Foam filter PROPERLY, K&N is junk compared to it. Put on some rubber latex gloves and rub the filter oil into the filter.