K&N or Uni not the question your thinking

[400exrapes]

the perfect jetting for my quad is a 150 man and 40 pilot with a slip on hmf spotr series now i know thats not the case for others but lets say i put an aftermarket air filter uni or k&n and left my lidon and put on of those covers for the filter on, would i need to bump my main jet up to a 152 or will the 150 still be alright?

[Eviltanker]

might need a 152, depends on elevation and temps as you know. I would say yes a 152 to be safe.

[underpowered]

if you went with an uni, a jettine change would not be AS important as if you went with a K&N. but i would suggest you atleast check you jettin either way, it may or may not need to change it.

[hornetgod13]

K&N Filters and UNI Filters allow more airflow than a stock filter. Why install an outerwears if you're keeping the lid on? Those are better used with the lid off.
If you do go with a hi-flow filter, I would recommend going up a jet size on your main and fine tuning your fuel screw.

[Barrymaxx]

A properly oiled k&n flows less that a properly oiled UNI. So you would need a bigger main with the uni, but the diffrence between flow of the k&n and the uni are not much.

UNI= protection
K&N= Waste of money and engine

[400exrapes]

great thanks for the help ill keep that in mind and also a friend of mine is just putting a k&n filter on his quad without jetting it thats the only part he has on it, do you think he will have to change anything? the elevation is about 300 ft and temperatures now are about 40 degrees and up to 99 in the summer

[JOEX]

Originally posted by Barrymaxx
A properly oiled k&n flows less that a properly oiled UNI...
First time i've heard this...:confused:

[Barrymaxx]

I was suprised when I first heard it too. I have pesronally talked to the guy that tested uni and k&n filters in 2 areas. Flow resistance and filtration abilities.

These tests were done on a flowbench. The k&n flows better like they say, but thats dry. No oil. Which would be bad for your engine in offroad conditions. K&N Must of forgot about that when they advertise. But when the uni and the k&n are properly prepared for offroad, the uni flows lsightly better. Probly not even noticible.

But during the filtration tests, the k&n didnt do nearly as well as the UNI, and the other foam filter they tested. Thay actually considers the k&n a "large particle' filter.

Another reason I choose uni is because there much, much easier to clean.

[JOEX]

Originally posted by Barrymaxx
I was suprised when I first heard it too. I have pesronally talked to the guy that tested uni and k&n filters in 2 areas. Flow resistance and filtration abilities.

These tests were done on a flowbench. The k&n flows better like they say, but thats dry. No oil. Which would be bad for your engine in offroad conditions. K&N Must of forgot about that when they advertise. But when the uni and the k&n are properly prepared for offroad, the uni flows lsightly better. Probly not even noticible.

But during the filtration tests, the k&n didnt do nearly as well as the UNI, and the other foam filter they tested. Thay actually considers the k&n a "large particle' filter.

Another reason I choose uni is because there much, much easier to clean.
Interesting....

Do you have any links or names to look into this further?

[Pipeless416]

Originally posted by JOEX
Interesting....

Do you have any links or names to look into this further?

i second this. i think if it was true, it would have been known a long time ago.

[400exrider707]

Yeah I find that hard to believe, and there have been numerous independent tests with air filters showing that the K&N flows more air, but also more particles (dirt).

[underpowered]

Originally posted by Barrymaxx
A properly oiled k&n flows less that a properly oiled UNI. So you would need a bigger main with the uni, but the diffrence between flow of the k&n and the uni are not much.

UNI= protection
K&N= Waste of money and engine

hmm, you are the one and only person i have heard this from and i have personally seen other test, show a K&N flows more air even when properly oiled than an uni or twin air. The K&N is a "large particle" filter, thats why you oil it to catch the smaller particles. a slightly dirty K&N is best as it catches more dust but still flows well. a properly maintained K&N will not harm your motor, but a K&N does require more mainenance than an uni does.

[Barrymaxx]

I did not personally test these filters, I am just going by what I read.

Heres the article. Its comparing it to a amsoil filter, which is comparable to a uni.


The Amsoil air filters will provide you with increased power and protect your motor far better than a K&N large partial screen. Many of you have been reading my bashing of K&N for some time now and that I call them large partial screens because that’s all they do is screen out the large dirt partials and let the smaller and more damaging grit into the motor. Now I will explain my distaste for K&N.

The flow bench doesn’t lie and what we are looking for is a filter that will have a large amount of flow with little resistance. The flow bench tests I will be talking about were performed using automotive filters of the same materials as the power sports filters and all filters tested were of the same size. What we are looking for is the amount of resistance each filter will have when pulling the same volume of air. This resistance is measured in inches of water.

This is how the flow bench works; it is a noisy machine that sounds like a oversized shop-vac. The motor and fan blades pull or push air through a hole on the top of the bench. The operator can adjust the direction and volume of the air passing through the bench opening. The resistance is displayed as a colored fluid is drawn up a metered tube.

The standard paper filter that most street vehicles use was represented by a Fram Filter. When the filter was positioned the machine was started to draw air thru the filter as it would be on the vehicle. Then the operator adjusted the machine to flow the pre determined amount of air flow. Then the inches of water was read from the tube. This process was repeated the same for each of the resistance tests and below is the results.

The numbers are the inches of water and the higher the number the harder it is for the air to get though, so you want the lowest number for the best performance.

5.00 Fram (new filter as it came out of the box.)
2.45 K&N (new filter as it came out of the box.)
2.40 Amsoil (new filter as it came out of the box.)
3.55 K&N (new filter serviced as K&N recommends for off-road use.)

As you can see the Amsoil filter flows a little more than a new K&N filter as it came out of the box. The Amsoil out of the box flows much better than the new K&N filter serviced as K&N recommends for off-road use. Amsoil has no changes needed for off-road use. So if all you are looking for is the best flow you want to go with the Amsoil filter, but what about filtering the air.

We can test the filtering abilities on the flow bench as well. A box is place over the opening of the bench and it has two openings in the top of this box that are covered with laboratory grade safety filters. All the air during the test will pass through these safety filters as the last restriction before passing through the bench opening. Next another box in places on top of the first box, this box has an opening on the top and this is where the filter to be tested is placed. Then a third box in placed on top and it has a smaller opening in the top of it. The top box will see a vacuum because of the restriction caused by the smaller hole in its top. A small hose like a fuel line inters the top box and this hose will draw air like a vacuum cleaner.

When the machine is turned on the flow will be the same for all the filters. The vacuum hose is used to suck up a standard laboratory contaminant from a jar called “AC test dust” and the same amount of test dust is used in all the tests. So as the dust is drawn into the top box it will spread out onto the surface of the filter being tested. Any dirt that the test filter lets pass through will be drawn down to the bottom box and onto the safety filters.

The K&N filter let a lot of dirt pass through and the safety filters were very dirty.

The Amsoil filter retained all the dirt and the safety filters were perfectly clean.

So the K&N filtered little of the test dust and would only stop larger dirt partials when installed in your machine. That sounds like a large partial screen to me.

Both Amsoil and K&N can be serviced but the oil wetted gauze is very delicate and you need to be very careful with it, the Amsoil foam filter is very easy to service and should last through many more servicings than the K&N.

When I had my shop my son worked the front counter and he would have fun calling me up to the front to look at a customer’s cylinder. There were many a time I would look into the bore and say “I see you have a K&N” the customers never could figure out how I knew because they did have one, I told them how I saw the mat finish and the heavy wear and sometimes traces of mud in the intake. I could usually tell them what oil they were using as well but that’s another story.

So even your street machines and hot rods would benefit from using the Amsoil filters with increased flow and filtering; and the K&N is usually about twice the price of the Amsoil filter.

Most of he street filters for Amsoil have changed to there new technology design that flows 5 times better and will stop even smaller dirt particles than the foam filters and will hold much more dirt allowing longer service intervals. The new filters are serviced and cleaned with a shop-vac from the outside or air hose from the inside and it is a dry filter so there is no washing or oiling. Sorry but Amsoil hasn’t made any of the new filters for the power sports market yet.

I see K&N is starting to make some foam filters now but that is old technology for cars and trucks. I think they still have a lot of catching up to do. It’s amazing what big buck advertising will do, I know many of the members here have been sucked up in their false statements and heavy advertising. Sure the magazines always use K&N in their projects but you need to realize that they will use what they get for free and K&N spends a lot of money in PR and promotions where Amsoil spends that money in R&D.

[Barrymaxx]

Accurate or not, ill never use a k&n.

[JOEX]

Where'd that article come from and who wrote it?

[hornetgod13]

I'm a UNI filter fan myself. You guys continue to misagree and waste your time and money on K&N filters. They are too expensive and take too long to clean and oil compared to a UNI filter. K&N filters are great for cars and trucks but, there are better filters made for off road vehicles.

[Barrymaxx]

Originally posted by JOEX
Where'd that article come from and who wrote it?
I pm'd you the link.

[NacsMXer]

Originally posted by hornetgod13
I'm a UNI filter fan myself. You guys continue to misagree and waste your time and money on K&N filters. They are too expensive and take too long to clean and oil compared to a UNI filter. K&N filters are great for cars and trucks but, there are better filters made for off road vehicles.

I couldn't agree more. I got a K&N on my blown F-150 but that's strictly street duty. I used to think K&N was the shizz back in the day on my 400EX till I
saw how much fine grit passed through it first hand. It was perfectly fine until I started MXing with it. Then there's always the people who say "you're not oiling it properly etc I have never had dirt in my intake tube". For some reason I don't think these people ride in the same conditions I do. When my K&N failed me on my 400, I was fullbore MX riding on dry summer days eating plumes of dust from whoever was in front of me.

I am completely unbiased towards any filter, the K&N wasn't up to the challenge...the results speak for itself. I switched to a UNI foam filter and not a problem since. I really think brand has nothing to do with it, it's just some filter designs are inherently superior to others in demanding off-road conditions :ermm:

[Barrymaxx]

That is the main reason I dont like k&n's. I ride in coal whicg produces a much finer dust that dirt. Its tough on filters.

K&n's are also a pain to clean...

[400exrapes]

two things how much horsepower does a stock 300ex and 400ex have? my friend thinks his 300ex completley stock has 25 horsepower, and two if he just puts a k&n with an outerwear cover on his stock 300ex and doesnt change any jets will he have any problems?

[NacsMXer]

Originally posted by 400exrapes
two things how much horsepower does a stock 300ex and 400ex have? my friend thinks his 300ex completley stock has 25 horsepower, and two if he just puts a k&n with an outerwear cover on his stock 300ex and doesnt change any jets will he have any problems?

Not quite sure on the 300 but I believe stock HP is around 17-18HP (feel free to correct me if that's wrong). The 400 has around 28HP stock.

The jetting would have to be slightly richer if he uses a K&N with no other mods but nothing drastic.

[400exrapes]

excactly what i told the kid but a dirtwheels magazine said the 300ex can push 25hp in the back of the january issue where all the 07 quads were

[NacsMXer]

Originally posted by 400exrapes
excactly what i told the kid but a dirtwheels magazine said the 300ex can push 25hp in the back of the january issue where all the 07 quads were

Well being that the 400 is known to have around 28 HP stock, I find it hard to believe that a 300 makes only 3HP less don't you think? I'd give the 300 low 20's HP max but someone on here knows what it is for sure.

[Ruby Soho]

are you supposed to re-jet when you put on an UNI airfilter? I put one on like 2 weeks ago and have ridden almost every day and only noticed an improvement.. so im guessing its fine?

[NacsMXer]

Originally posted by Ruby Soho
are you supposed to re-jet when you put on an UNI airfilter? I put one on like 2 weeks ago and have ridden almost every day and only noticed an improvement.. so im guessing its fine?

It is not a huge difference over stock but yes, the UNI does flow more air being that it is larger than the stock filter. I want to say you would be ok with how it is but at the same time the UNI will change your jetting slightly. What i'm trying to say is it's not super critical but there is a difference.

Most people just ball park it anyhow and do fine as we all don't have access to ATV dyno's with A/F sniffers to get it spot-on. I would definitely jet it richer in the winter months however as it will be even leaner during that time.

[400exrapes]

lol the 300ex's dont have low 20's i knew it was 17 but dirtwheels said an 06 could push 25 i read the section but they were smoking something and would a stage 2 hotcams or stage 1 hotcams be better for me if im only going to have a uni filter and s/o hmf but just a slip on for now?

[NacsMXer]

Originally posted by 400exrapes
lol the 300ex's dont have low 20's i knew it was 17 but dirtwheels said an 06 could push 25 i read the section but they were smoking something and would a stage 2 hotcams or stage 1 hotcams be better for me if im only going to have a uni filter and s/o hmf but just a slip on for now?

lol, obviously but I was giving the most generous possibility....just like lemons there's always "factory freaks" as well. Would definitely take a slew of mods to get it into the 20's.

As for the stage 1/2 Hotcam it depends on your riding style. Stage 1 is more of an "all around power" cam with the emphasis on low-mid power. The stage 2 is more aggressive with its power range shifted to mid-top.

[400exrapes]

stage 1 is the way to go then