K&N Air Filters

[Alajambama]

Does anyone use K&N air filters on their bikes? I have used them for years on my other vehicles and they are a great investment. I was just wondering if their dirt bike filters are as beneficial as the ones they make for cars and trucks. $90-$100 is a good bit of cash for a dirt bike air filter.

[Bolon Yokte K uh]

I would never use a K&N on anything that runs in dusty conditions.

[orangyktmthing]

Stock, twin air or uni. K & N filters in a dirt bike are asking for trouble. K & N filters let more air through, but in the counterpoint, they also let more dust and fine silt in past the filter. Another thing is, if you read the small print, they only give you a year warranty on offroad machines, I guess that they don't feel that confident when the filters leave the pavement. Of course, for every person that (in my case) says that they wouldn't put one in, I'm sure that there will be someone that would put them in.

[Dr GoFast]

they will let more air through but they don't filter as well as foam.

[billbanshee]

I would never use a K&N on anything that runs in dusty conditions.

x2

[Mike38]

Here we go again! I'll just re-post what I did 3 months ago......

Posted 20 November 2011 - 03:52 PM

My nephew that races at the Pro level claims 2.5 horse power increase from a stock 2011 CRF450R. Done on a dyno, by a impartial party. All he did was install a K&N filter and set the fuel injection accordingly for the higher air flow.

K&N filters do not allow any more dirt pass threw them then any other air filter, as long as they are properly maintained. Rinsing a K&N in pre mix thinking you cleaned and oiled the filter all in one shot, is not proper maintenance. You must use a K&N recharge kit.

Mater of fact, a properly maintained K&N filter will stop dirt particles that are smaller then dirt found naturally in gasoline. There is a certain amount of “dirt” found in gasoline. Better grades of gas, have less and smaller “dirt” particles, but a certain amount is always there. If memory serves me, it is common to find dirt particles in fuel that measure 3 to 4 microns in diameter. A properly maintained K&N filter will stop particles as small as 2.5 microns. Therefore, the gas you are using is doing more damage to your engine then the K&N filter is.

Pro Flattrack racers, at the GNC level all use open K&N filters on their twins (Harley XR750 for the most part.) A Harley XR750 engine costs right around $12,000 to buy, and then you have to build it because it comes as a parts kit. Do you honestly think someone would spend that kind of money on a motorcycle engine, and all the labor involved assembling it, then run a junk air filter?

I do not work for K&N. I do not sell K&N products. I have been using them successfully for over 35 years now.

[Lead Head]

K&Ns let tons of dirt through compared to other filters. 2.5 Microns is still quite large for dust particle size. Most automotive filters are effective down into the submicron range. I've seen plenty of destroyed diesel turbochargers from K&N filters, even ones that have been properly cleaned and oiled still let enough dust through to effectively sand-blast a turbo. With the same surface area, you simply cannot flow more air while still filtering better.

You are not going to get 2.5HP from a K&N. You'd be lucky to get 2.5HP on a truck from a K&N, let alone an already strung-to-the-max race MX engine. I'm betting the majority of that 2.5HP came from fixing Honda's poor factory EFI tuning, then anything the air filter did.

Also, the statement that gasoline is doing more damage to your engine than the filter is just a blatant lie, for a number of reasons. In a dusty environment, there is a far greater amount of unwanted particles in the air, than in your fuel, or how about the fact for every pound of gasoline you burn, you consume around 13-14 POUNDS of AIR. Think about how many dust particles on a dirty MX track there must be in a pound of air.

I'm also not sure how comparing a loose tolerance, low revving (relatively), air cooled, huge oil-sump, pushrod Harley engine is in anyway relavent to a liquid cooled, tight tolerance, DOHC, high revving, small oil capacity engine is in anyway relavent.

Edited January 25, 2012 by Lead Head

[weantright]

I would never use a K&N on anything that runs in dusty conditions.

^{Right from a K&N tech in the R&D department.}

^Myself

^{"I can see tiny holes in the filter. Is the filter defected?"}

^Tech

^{"no that's how we flow more air. Not the best for dirt prevention but no one else flow as much air as we do."}

^{I asked this many years ago, have they changed??}

^{I wont even use it in on-road motors.}

Edited January 25, 2012 by weantright

[orangyktmthing]

Here we go again! I'll just re-post what I did 3 months ago......

Posted 20 November 2011 - 03:52 PM

My nephew that races at the Pro level claims 2.5 horse power increase from a stock 2011 CRF450R. Done on a dyno, by a impartial party. All he did was install a K&N filter and set the fuel injection accordingly for the higher air flow.

K&N filters do not allow any more dirt pass threw them then any other air filter, as long as they are properly maintained. Rinsing a K&N in pre mix thinking you cleaned and oiled the filter all in one shot, is not proper maintenance. You must use a K&N recharge kit.

Mater of fact, a properly maintained K&N filter will stop dirt particles that are smaller then dirt found naturally in gasoline. There is a certain amount of “dirt” found in gasoline. Better grades of gas, have less and smaller “dirt” particles, but a certain amount is always there. If memory serves me, it is common to find dirt particles in fuel that measure 3 to 4 microns in diameter. A properly maintained K&N filter will stop particles as small as 2.5 microns. Therefore, the gas you are using is doing more damage to your engine then the K&N filter is.

Pro Flattrack racers, at the GNC level all use open K&N filters on their twins (Harley XR750 for the most part.) A Harley XR750 engine costs right around $12,000 to buy, and then you have to build it because it comes as a parts kit. Do you honestly think someone would spend that kind of money on a motorcycle engine, and all the labor involved assembling it, then run a junk air filter?

I do not work for K&N. I do not sell K&N products. I have been using them successfully for over 35 years now.

Like I said, different strokes for different folks....

Although, you said that it produced 2.5hp more on a dyno, which is in controlled conditions, not with roost hitting the bike and the such. Hey, run what you want, isn't that the great thing about this sport/hobby! I wouldn't run one, seen silt/dust particles in a properly oiled/installed filter compared to a properly prepped foam filter.

[Jakeblues]

Pro Flattrack racers, at the GNC level all use open K&N filters on their twins (Harley XR750 for the most part.) A Harley XR750 engine costs right around $12,000 to buy, and then you have to build it because it comes as a parts kit. Do you honestly think someone would spend that kind of money on a motorcycle engine, and all the labor involved assembling it, then run a junk air filter?

I do not work for K&N. I do not sell K&N products. I have been using them successfully for over 35 years now.

Yes, they are racers, and if it gives more HP they will do it.

[Jakeblues]

And the cost effective argument does not apply since you already have a re-useable filter.

[davek18]

I have seen engines destroyed in rice racer Honda's by dirt ingestion due to K&N's and clones. True, not a loss really but the principle still applies to real machines.

[YZrider2112]

My dad has had one on his Husky 450 for a couple of years. He keeps it well maintained and it doesn't seem like anything is worse off.

MXA reviewed one in a YZ450f and said it increased HP .83 at peak, and they had no complaints about letting more dust in. In fact I think I remember it saying something about it stopping dust better and better as it gets dirty.

No idea if any of this is true. I wouldn't hesitate to run one.

[bushman45]

K&N filters are junk, you'll ruin your engine using them. they have been screwing people out of money for over 40 years. they pass more air thus more dirt. does anybodynow how much vacuum pressure an engine produces? also do you know the size of 1 micron? you run your grout sponges, i'll stick to the oiled gauze. maybe when someone comes out with PTFE filters i'll switch.

[zilla]

I used them back in the day.. Had afew on my truck as well.. can't say if they worked better or worse than a foam filter, but they are a PITA to clean and oil.. I went back to paper on my trucks and foam in my bike..

[orangyktmthing]

My dad has had one on his Husky 450 for a couple of years. He keeps it well maintained and it doesn't seem like anything is worse off.

MXA reviewed one in a YZ450f and said it increased HP .83 at peak, and they had no complaints about letting more dust in. In fact I think I remember it saying something about it stopping dust better and better as it gets dirty.

No idea if any of this is true. I wouldn't hesitate to run one.

Dirt rider also did a test on one, and Jimmy was gagging on how great they were. I don't trust magazine tests, considering that they are probably given filter(s) and paid for the "non-biased" tests/opinions that they give. Hell, a couple issues later, they even gave dirt rider a tour in the factory......

[Mark6299]

I would never use a K&N on anything that runs in dusty conditions.

Stock, twin air or uni. K & N filters in a dirt bike are asking for trouble. K & N filters let more air through, but in the counterpoint, they also let more dust and fine silt in past the filter. Another thing is, if you read the small print, they only give you a year warranty on offroad machines, I guess that they don't feel that confident when the filters leave the pavement. Of course, for every person that (in my case) says that they wouldn't put one in, I'm sure that there will be someone that would put them in.

they will let more air through but they don't filter as well as foam.

Well I guess Dirt Rider magazine is into steering people in the wrong direction on purpose. Why??? I don't know maybe they want people to stop buying the magazine. Just sayin. I bought one for my new to me YZ250 last year before even unloading it off the trailer. I posted the same exact question the OP did. I felt like a little tiny ant for even asking such an evil question. I didn't install it and was able to take it back. So here we are again. I haven't read the article in Dirt Rider for the K&N yet but it's sitting on my desk. I guess I will go ahead and read the LIES they published in millions of copies of Dirt Rider.

[orangyktmthing]

Well I guess Dirt Rider magazine is into steering people in the wrong direction on purpose. Why??? I don't know maybe they want people to stop buying the magazine. Just sayin. I bought one for my new to me YZ250 last year before even unloading it off the trailer. I posted the same exact question the OP did. I felt like a little tiny ant for even asking such an evil question. I didn't install it and was able to take it back. So here we are again. I haven't read the article in Dirt Rider for the K&N yet but it's sitting on my desk. I guess I will go ahead and read the LIES they published in millions of copies of Dirt Rider.

Think of it this way, do you really think that they aren't getting paid for stuff that they put in their magazine?

[Mark6299]

Think of it this way, do you really think that they aren't getting paid for stuff that they put in their magazine?

Sure they are. Like I said i gave mine back. Just makes you wonder about whats really up. How are we to be truely informed about what we but?

[orangyktmthing]

Sure they are. Like I said i gave mine back. Just makes you wonder about whats really up. How are we to be truely informed about what we but?

That is the million dollar question. The oems are obviously going to say that their stuff is the greatest and the aftermarket is also going to say that their stuff is the greatest. Myself, I stick to purchasing things that I have seen work, so I might use something that other people disagree with, but hey.....