View Full Version : Clean Air For Your Steel Pony's Lungs

03-07-2011, 03:32 PM
K&N has quite a following, but they are not really complete w/o some kind of foam element filter that further cleans the air after it has gone thru the mesh pre-filter, then the K&N.
It is fairly common to put a foam element OVER the K&N, but this means that the foam is doing the lion's share of the work.

(Long ago in the desert we used to pull a Filtron "sock" over our then new K&N's. Water would pass thru the foam taking dirt with it to be found in the carb.'s throat as well as increase wear of carb. slides and everything else. Water would NOT pass thru BOTH filters together 40 years ago, and probably will not NOW.)

I believe you are better off with a tractor or heavy equipment type of diesel cannister filter that is composed of 1. a cyclonic dirt trap, 2. a large deeply pleated paper or fiber pre or 1st stage filter and a secondary filter as well.

I got a small two-stage cannister-type filter from the Kubota agency that I shall try to install on my Ural Gear Up.
It is regularly installed on a 900cc diesel, so I believe it will be more than adequate for a much lower compression 750cc gas engine.


03-07-2011, 03:36 PM
Very important - good filtering of air when off road.

Likewise very important is a good snorkel system.


03-07-2011, 03:47 PM
Good to hear from you ALWAYS, Anthony! :-)
There was some bike or other in the long ago past that had the filter and intake inset into the top of the bike's gas tank.
This would still be a primo location on a mo-sicle sicne the lower down you go the thicker(er;-) the dust gets.
IT woudl take alot of weldign on (best woudl be NEW) the gast tank and woudl neccessarily reduce the fuel capacity.
It's worth cosndiering if you coudl find a really superior paper element for some modern vehicle that woudl be the right size to fit the toolbox recess you woudl be modifying.

Mine (if I can get it mounted) will have a short snorkel up under the bike's saddle.


03-07-2011, 03:50 PM
Yeah thanks for bringing this up. K&N will tell you that their filter will increase horsepower but you can also increase horsepower by completely taking off the air filter! K&N does not advertise better filtration, just more hp! The really fine dust is not stopped by a K&N, especially desert dust. I learned this the hard way when I got lots of dust in the factory built in filter in my Tundra then I switched back to a regular filter. I've never heard of putting foam with a K&N, is this somehow superior to a regular paper/cotton filter?

03-08-2011, 07:48 AM
I thought that the point of the K&N filter was increased surface area of "better" filter media and therefore increased airflow resulting in better HP. My personal experience is that I got noticeably better HP on my F350 turbo diesel but that's a diesel not a gas vehicle. Diesels are basically big air pumps so it could be that it makes a bigger difference?? I'm no mechanic, I just notice stuff that works for others and buy it. Seems like putting a foam filter around the K&N would REDUCE airflow and therefore nullify the original advantage gained.

03-08-2011, 08:30 AM
Well I'm not off roading like you guys but I recently put a K&N in my HHR and I gained almost 2 MPG now. Every bit helps with the gas prices they are currently.

03-08-2011, 09:13 AM
Good to hear from you ALWAYS, Anthony!No.
Good to hear from YOU! - You post too little.

This thread really is a great excuse for us (WT) to discuss and 'hash out' the best air filters & snorkels for SERIOUS off roading.

Sort of like this: - An old thread of mine:



03-09-2011, 10:20 PM
I'll chime in on this - I HAVE had problems with K&N's, and no longer use them. About the only thing I'd use them on are race vehicles. When I got my Diesel Suburban, the PO used K&N, it was oiled properly, looked good....and had fine grit on the inside tunnel. I've since gone to a custom air filter, using large filter elements from medium duty trucks. Also race stuff (UMP), but these last much longer, work better, and have commonality. Much of it depends on where you're using them - if you never go into dusty areas, probably won't have problems. If you do.....

03-10-2011, 09:15 AM
Hmmm, sounds like I need to reduct my bike and change out the filter then. Just got a Blast that already had the K&N filter on it. Problem is, I live on a dusty dirt road...

03-10-2011, 10:05 AM
I've added the K&N to two of my vehicles. Picked up 2 - 3 MPG depending on how I behave.

As gas prices have gone up I've worked harder to keep my Xterra below 2500 rpms which requires that I be more patient about accelerating. I get about 20 mpg out of it with a clean filter and a light foot.

07-18-2011, 10:14 AM
Just use a foam UNI or similar as the final filter INSIDE(secondary filter) the K&N(primary filter), if you can engineer it.
If not, pull one over the outside of the K&N...Both have their strong points and together they make a kind of "two-stage" filter that will work better than either would individually.


M1A's r Best
07-18-2011, 06:20 PM
Haven't bought an ATV since 1986 (got one of the best then - a Honda 350X - 4 stroke, more torque than I can use and a 6 spd. manual transmission) but back then they had two stage air filters. A paper cartridge type filter with screen reinforcing inside it and rubber on top/bottom to seal up in the air box. On top of the cartridge filter was an oil soaked (oil it, squeeze the excess oil out and stretch it around the canister filter and install both in the air box) foam filter that could be quickly/easily cleaned "on the road". I took care of my bike but I road with guys who would start having hard starting issues or the engine dying when going slow and then giving it the gas. Pull the filter and sure enough it would be downright nasty. Pull the foam cover off the cartridge filter, grab the spare gas can (several of us carried 1 gal. plastic cans) and pour a little gas on the dirty filter and rub it between your hands. Sometimes you had to do this 3 or 4 times to get it mostly clean. The gas would air dry quickly on a hot summer day so the filter was ready for oiling. It just happens that the only folks in the woods who don't have to worry about getting a citation for dumping trash are the loggers so its easy to find a location where they've been working (and changing the oil in their equipment) and grab a few cans of "not quite empty" oil and use what's left in the bottom of the cans to re-oil the filter before reinstalling it. After than the ATV starts like it should and runs great, again. Oh, you can also use that oil left in those cans to oil your chains (yeah, I know, everybody had drive shafts these days but I started ATVing in the early 80's when a drive shaft ATV was really rare (and slow.)

As to K&Ns, I use them on every vehicle I have except my new Genesis Coupe. My IROC Z28 has 186,000 miles on it and runs like a top. My Ford F150 4WD PU had 251,000 miles on it when I (screwed up and) traded it in on a new Fusion for my wife. My Jeep Cherokee has 108,000 miles on it with no issues so far. One S10 Blazer has over 180,000 miles on it and the other is just past 135,000 miles on it. Oh, the new Fusion doesn't have a K&N in it (yet).

Its not dusty here in Richmond, VA and I don't off road down here in the flat swampy lands.

07-20-2011, 05:53 PM
ATK had air filter mounted in/near gas tank.