k&n filter vs uni filter or other foams

[dwnlowx]

i am running a foam uni filter now wondering if those k&n air filters are better and i was thinking of some diamond shape cuts on my air box so it will grab tons of air,then do the k&n and a bag cover and some more jetting then maybe on the dyno , any input would really help

[jgerdi]

I saw this question before and was curious my self. Do a search on " twin air power flow" just in our forum. You will find more info than you probably want. My conclusion was that.. 1 You must filter the dirt from the air and that in it self is restrictive. 2 my bike already has more power than I can use. 3 If you want to turn in faster lap times , go faster in the corners like those little b-sterds on 85's that keep passing you. 3 I have 5 bikes to maintain , they all get a filter skin on top of the uni filters which allow us 2 rides with the filterskin and an additional 2 rides with just the uni filter and then we clean filters and change the oil all at once.

-------

06 450 Le

04 Suzuki rm 125

04 Cr85 expert

04 Cr85

04 crf 150

00 triumph sprint rs

A little extra on all bikes.... GOD I love my garage..

[grayracer513]

K&N filters have the potential to filter better than foam. Unfortunately, they rarely live up to that because, like foam, they depend on being thoroughly and uniformly oiled to filter well, and they vastly more difficult to oil properly than foam, mostly because they just can't be squeezed into a wad.

Foam filters mostly flow marginally more air, too.

Unless you are running Super Moto, cutting holes in your air box will do nothing more than allow more dirt to get to your filter. The stock configuration lets more air in than the carb can pass, and makes it difficult for water and heavy debris to follow along. At very high speeds (over 90), there can be air flow problems around the rider that might be helped by certain air box mods, but your dirt bike is better off left as is. If you have an '02 or earlier, I recommend doing This mod to it to make changing the filter easier, but that just makes it more like the '03 and up air box.

[crazycracker]

i gots me a k and n, i dont know why people dont like them. you can ride longer with them , and a lot easier to maintain. ive had no problems with mine, i think it was worth the money. i also would not belive that a foam filter can flow more air, there is a straigher flow of air through the k and n verses a foam filter, where the air is swivling around to get from hole to hole. do what you want, its your bike

[flintlock28]

I'd be leery of using the K & N for Dirt applications. I think they are great filters for street use ( I use one in my F-150), but I have read a number of posts from people on these forums, who have experienced dirt getting past the filter, showing up inside of the intake manifold, which means inside the engine. I can't remember if it's the seal, or just from the filter itself not trapping some fine/silty dirt, but there has been more than a few posts about it....... I'd stay away.

[450_rider]

I had a K&N it worked good the first time on my bike but after that it was just a complete pain to clean! and if you don't clean it right its still full of dirt and slows the air down. I switched to a Uni and the ease of cleaning it where much better so it turned into more horsepower for me. I never noticed dirt in the air boot, but i also but the grease around the edge since it came with it. Stick with a Uni much much better. ?

[grayracer513]

i gots me a k and n, i dont know why people dont like them. you can ride longer with them , and a lot easier to maintain. ive had no problems with mine, i think it was worth the money. i also would not belive that a foam filter can flow more air, there is a straigher flow of air through the k and n verses a foam filter, where the air is swivling around to get from hole to hole. do what you want, its your bike

The flow of air through a K&N isn't as straight as you'd like to believe, for one thing. It does flow quite freely, and only the better foam filters flow more freely. You may have missed that point because you did not understand the term "marginally". However, you cannot ride longer with them (they clog faster), and their ability to trap and hold a heavy volume of dirt is somewhat limited.

You say you find them easier to maintain. Pehaps you can describe your maintenance routine for us.

[Blue4Ever]

Save your money! The Uni will flow better. If you feel the need to get more air flow, which is only going to help on top. You can get a 2 smoke YZ filter cage and a Twin Air backfire filter. The 2 smoke cage has no screen. I had a long conversation with a Fire Tech who informed me that when they do testing there is a hugh difference if they close a screen door vs leaving it open.

[grayracer513]

Your analogy doesn't work. Removing the screen, but running an air filter is like opening a screen door at one end of the hallway while the one at the other end stays shut.

I have also done quite a bit of testing on this. So did Doug Henry's Super Moto crew on the YZF he rode before he went to the Timex team. After trying a number of various air box and filter, screen/no screen combinations on a dyno, their conclusion was that there is no advantage to removing the backfire screen because the filter itself is more restrictive than the screen is.

[Blue4Ever]

I would like to see these test results by Doug's crew! You are correct about the filter it's self being more restrictive, but you also have three times the surface area which will allow for a greater volume (mass air flow) if there is no or less restriction prior to.

The door would not be shut at the other end but rather pulling air thru a much larger screen door w/fine screen then passing thru a much small screen w/larger mesh after that.

I do agree there is only a small difference at best!

[yamahacrazy_310]

I liked the K&N air filter on my 03 YZ250F cause it has a life time warranty. Yes they are a pain to clean but it is worth it in the long run.

[grayracer513]

The info about Henry's bike was never documented that I personally saw, but my opinion of the credibility of the source is very high. I guess that means that what it's worth to you depends on your opinion of my opinion. ?

In my testing, I mounted the air filters on a 12" duct leading to the intake of a 40 CFM HVAC fan and connected a water manometer 1" downstream of the filter. There was no difference in pressure drop across the filter with or without the screen in place. With the screen only over the opening (no foam filter at all), the was a significantly smaller pressure drop. My conclusion from this is simply that the foam filter is the more restrictive of the two, and that removing it accomplishes nothing in terms of mass air flow.

It isn't a question of the media being more restrictive per area, but of the actual clean and oiled filter as it is used.

I also did some fairly entertaining blind rider testing that demonstrated a rather remarkable placebo effect for the mod.

[bg10459]

Do a search on "backfire screen dyno" and you will find that none of those who advocate removing the screen provided dyno results to support their claim. The dyno results that were provided showed that it made VERY little, if any, improvement. ?

However, if removing the screen makes you think it's faster you might turn faster lap times because of increased confidence that it is.

Following that logic, you may also turn faster lap times if I told you I optimized your fetzer valve. ?

[crazycracker]

i shall tell you how i clean my k and n, i take it out of el air box, then spray the k and k cleaning solution to it. wait ten minutes and wash it off. after half an hour the k and n is dry so i start with spraying the oil on it. let it sit for ten minutes and touch up any white spots i see. this is hows i clean my k and n, ya see

[Blue4Ever]

s stated prior the screen will only make a small difference at best!! The thread was about K&N vs foam. Foam is the way to go! Less $, 2 for the price of one, so one is always clean and ready to go.

bg10459-Were did I state that this mod will make you or myself faster? Your must have something stuck in your fetzer valve!

On our modern bikes the only mod that will truly make a noticeably positive difference in your ability is suspension. Then saddle time. All the other stuff we do to our bikes makes the bike perform better! NOT us!

The best way to get faster is to RIDE! RIDE! RIDE!

[Dirty_Sanchez]

I'm so confused.

I think I'm just gonna keep using that old stretched out tube sock smeared with lard I found down the street awhile back.

I rub the left over lard in my hair. It makes it shiney and the chicks really dig it. ?

Dirty

[grayracer513]

this is hows i clean my k and n, ya see

Yes, I see. And what assurance do you have that the media is thoroughly through-oiled?

None.

[barch88]

I just bought the OIL type filter oil...not the spray. I poured some in a bag, soaked my filter in it, then let it sit over night, squeezed any excess off, then put it in my bike. Entire filter was tacky, inside and out, and I assume in between since I soaked it through and through.

[bg10459]

bg10459-Were did I state that this mod will make you or myself faster? Your must have something stuck in your fetzer valve!

My post was not directed at you personally, it was provided for the reader in general. I'm sorry you took offense.

However, while my post was somewhat in jest, I do believe in the power of suggestion, especially when you're trying to shave seconds off a lap time. The confident rider is bound to be faster than the timid. Coaches often motivate players to succeed against tremendous odds.

FETZER VALVE (related info for the reader in general).

I like foam filters with belray filter oil. ?

[grayracer513]

while my post was somewhat in jest, I do believe in the power of suggestion, especially when you're trying to shave seconds off a lap time. The confident rider is bound to be faster than the timid. Coaches often motivate players to succeed against tremendous odds.

I often toy with the idea of marketing a line of products under the trade name "Black Feather Racing" ?

12 points if you can tell me what the significance of that name is.