If you want the best of both worlds take a look at Notoil foam filters. They provide the fine filtration of foam but actually flow better than K&N.

 

Note to self: Washing ***** with foam will not stop little swimmers.


GOT IT! [img]i/expressions/face-icon-small-happy.gif[/img]


Learning all kinds of new stuff around here! lol! [img]i/expressions/face-icon-small-wink.gif[/img]

 

I have the foam Notoil on my Raptor and it works just fine. We have been using both foam and K&N for many years. We prefer the foam in the dirt, and the K&N in the sand (with an outerwear).
I always carry a spare filter ready-to-go. This allows me to do the nasty cleaning and re-oil in the garage at my own pace. I prefer to clean and re-oil the K&N, over the foam.
BUT, both have to be done according to spec! My friend just told me he blew out his air filter with compressed air. I said what kind of filter? He said K&N. I said take a close look at it! He had blown small holes in the cotton fiber! K&Ns can be easily damaged.
But, if you get too much or too little oil on the foam filter, it also will not perform well. So pick you poison. But read the instructions and follow them. It's a lot cheaper than a rebuild!

Better yet....get your girlfriend to help you re-oil and get Kinky!

 

Why are so many quad riders blind about horrible filtration with K&Ns in dusty contitions while every single dirt bike rider knows beyond a shadow of a doubt that K&N will ruin a motor? Could be that most dirt bike riders have been around much longer than quad riders or could just be the BS hype put out by some quad performance shops plus there is all that K&N advertising in quad market when they seem to have conceeded the dirt bike market. Believe ixRAZO. He knows what he is talking about.

 

Ran K&N for over 6 years on one and never had a problem related to dirt in the engine. They filter just fine.

 

Looks like the advertising boys have gotten to you too, just different ones.

 

Been running K&N for 5 years on 2 bikes - no issues.

I usually remove the filter, clean and re-oil after every other ride.

 

There was a study done on this a few years ago in the construction industry. It was done because paper elements on heavy equipment seeing near continous duty required such frequent replacement that the reusability of the K&N was a significant cost advantage. The conclusion was that the test engine equiped witht the K&N had significantly more cylinder bore wear than an identical engine using a paper filter, and that the decreased interval between overhaul would not make up for the savings. If I remember it was also noted that dust was evident inside the air intakes after the filter on the K&N. This is in a situation where the filter is essentially surrounded/submerged in dust.

Now this doesn't neccesarily apply to ATV's as the circumstances were different, but it is has been scientifically shown that the K&N (w/o outerwear) passes more dirt than a comparable PAPER filter. How it compares to a foam filter, I don't know. Personally I use K&N's on every thing I can, I'm even looking for one for my chainsaw.

 

Look at the composition of a paper filter and a cotton gauze filter. If you notice, there is a lot more obstruction by the paper filter. This leads to better filtration, and considerably less airflow. Foam is in between, filters better than gauze, but not as well as paper. All the while it flows better than paper, but not as well as gauze.

Its kind of a simple thing if you look at it. The more filter you put in the way, the more you will filter out. But you will have more filter in the way, so its a less porous barrier and you will flow less. Doesnt matter if you are talking about liquid, gas, air, or anything else, the principles are simple and the same. This should not be a difficult concept.

The real question then becomes about circumstances. Does the gauze filter well enough for my application? Does the Foam flow enough for my application?

Now heavy equipment does not need to be run at peak hp and the engines are not tuned for maximum flow, but rather durability and the successful completion of the job. An atv is more performance oriented, most buy new filters and other upgrades to make them faster and more powerful. So it should be obvious to an observer that the heavy equipment owner will want something that filters better because performance isnt as crucial, while the atv owner can afford to sacrafice a little filtration in order to flow more air and create more power.

So for one application a paper filter may be idea, in another a foam is the proper balance of flow and filtration, while for another application the added flow of gauze outweighs the filtration differences.

 

Tests I've seen showed foam flows almost as well as cotton gauze but doesn't filter any better (note I said "almost" flows as good). And that was without any outerwear. I agree paper is the most restrictive and has the worst flow, but filters best.

Way I figure you have 2 choices to get more air through a filter: 1. increased surface area, which the K&N does through pleats. 2) more "pours" material that allows higher flow, which both K&N and Uni do but you are giving up some filtration ability.