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What air filter is the best?

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I need an air filter for my 96 xr250r. In Dennis Kirk they have "No Toil" $24,"K&N" $46, "Uni" $28, "Twin Air" $26, and

"Moose" $21. It sounds like most of you run the Uni, and some have had problems with the No Toil's not seating right.

What about the others? and are K&N's that much better?

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I'm running the Uni on my 2003 XR250. I find it easy to clean, comes with its own high-flow cage and seats real well. Not a bad price either.

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I find the stock cage (w/o back fire screen, mind you) tends to give better feedback than the UNI cage as to when it is properly seated. This was less of an issue with the older (pre 1996) airboxes that had a tin lip to center on. The newer box has rubber edges and less room in there for folks with bigger hands (combined with the non-removable lid that doesn't swing 100% out of the way). Here is something I had written up earlier for something else. I'll paste it here anyway.

Q: What air filter will filter the best?

This is almost as religious a topic as recommending a motor oil, but

for what it is worth, I've had the chance to compare three different brands

of filter at the same time (K&N, UNI, and new OEM Honda). These style filters

fit essentially all the XR's except for the liquid cooled XR650R and date

back to the "KN5" XR350 of the early '80s.

Air filtering in a foam filter (as I understand it) relies on the fact

that the momentum of the dirt particles means that they want to travel

in a straight line. As the air dips and bobs through the foam, the dirt

should eventually plow into some oily foam and stick. However, as you go

to finer dirt, the momentum of a dirt particle is less and it has a better

chance of being steered through the filter along with the air stream.

Both the Honda and the UNI are two stage foam. The interesting thing is

that the "fine" foam on the UNI is about the same pore size as the coarse

outer foam on the Honda. If you hold the Honda filter up to the light,

you can't even see any illumination through it, let alone straight through

light. With the UNI, you get a yellow illumination from the yellow inner

foam, and if you look closely while moving it around, you will see a few

tiny rays of light make it straight through. This is for clean, non-oiled

filters. So which is better? I'd say it depends on your application and

that can be broken down into terrain and whether you race or ride

recreationally.

In eastern terrain, where you are probably filtering more wet

dirt, bugs, grass seeds, chunks of leaves, etc. and less fine fine dust,

the stock filter may tend to skin over, as the larger particles get trapped

very close to the surface while the rest of the filter remains relatively

clean. I think this is what UNI has targeted with the coarser outer foam

on their product, with the idea being that the larger particles are

dispersed through that layer instead of growing a restrictive layer over

the surface. But in dry dry dusty conditions, having the filter skin over

is probably less of an issue, and I'm thinking the higher foam density of

a stock filter will mean that there is more oily foam in the path of the

air and thus it will pick up a little more of the fine stuff than a UNI.

The second part of the application depends on why you ride your bike.

Are you a racer where maximum flow and minimum risk of plugging

is most important? Or are you just out to have fun, and thus maximum

filtration and maximum engine life are your top concerns?

No, I didn't forget the K&N. It is a totally different animal, more

like a paper car element in design. The air only has to pass through

a layer of cotton, and filtration depends largely on the size of the

weave of the cotton. Although as others have pointed out, I can't say

I'm in love with the quality control of the gaps in the cotton weave,

with some gaps appearing to let quite a bit of light through; much more

than the tiny amount you see through the UNI. It also doesn't hold

as much oil (obviously) - and I equate stored oil with the amount of fine

dust the filter can hold onto before becoming "dry". The other downside

is that on this K&N filter (XR250/XR400/XR600) you get a tin lid on

the filter front, instead of useful filtering area. In its defence,

I'd have to say that it is only 1/2 a filter when used alone - K&N

sells pre-filters or "filterchargers" as I think the marketing droids

have called them. I'd recommend using a pre-filter on a K&N and always

keep the assembly well oiled. There are independent tests that you can

find on the internet that show the cotton gauze type filters don't filter

out as much stuff as a foam filter until they get some dirt on them.

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The Uni's are kinda scarce around here, so I first bought a Twin-Air, and then a No-Toil for my 400. My main complaint with the Twin-Air, was that it was a B---h to get over the stock filter frame (firescreen removed). It appears to be a little higher quality than the No-Toil (better seams and a more finished look), it was just a fitment problem. The Twin-Air also seems to be a little denser foam and should provide better filtration, (and possibly more restriction). The No-Toil fits the stock screen better(a little bigger), and has more overlap on the bottom to seal against the airbox face.

Another subject (and question). I had been using the Silkolene filter oil, and liked it, but I was out and picked up some at the Suzi dealer, and all they had was PJ1.

Man, that stuff is like bubblegum. I'm sure it traps dirt really well, but it's a mess to work with. Has that been anyone elses experience? I'm going to have to find some of the No-Toil filter oil to try.

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THE INFORMATION THAT WAS PREVIOUSLY STATED WAS VERY INTERESTING! (COMPARED FILTERS)....I WAS NOT SO CONCERNED WITH HOW LONG AND HOW WELL THE FILTER WORKED, BUT WAS CONCERNED WITH PERFORMANCE. THE K&N FILTER GAVE MY BIKE A BOOST. I CLEAN IT REGULARLY AND HAVE NOT HAD ANY PROBLEMS WITH IT. I RIDE AN XR400 BUT IM SURE IT IS VERY SIMMULAR. THE ONLY DRAWBACK IS THE K&N FITS VERY TIGHTLY IN THE AIR-BOX AND IS MORE $$$. KINDA HARD TO GET TO SEAT! I THINK IT IS WORTH IT THOUGH. BUT THAT IS MY OPINION, AND YOU KNOW WHAT THEY SAY ABOUT OPINIONS:usa:

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i use the K&N filter and is happy with it, but i do think that the stock and uni is more protective thou less air "effective",

mightynorsmen: there is a button on your keyboard that says "Caps Lock" -push it once :cry:

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I bought the K&N wasnt very impressed with it, if you read the instructions closely it says something to the effect that the dirtier the air filter the better its works :cry: anyway used 2 or 3 rides and its hanging on the wall :cry: switched back to the UNI :cry: BTW since i bought it but not currently using it, isnt there some unwritten law that says i can keep the cool K&N sticker on my fender. :cry:

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I need an air filter for my 96 xr250r. In Dennis Kirk they have "No Toil" $24,"K&N" $46, "Uni" $28, "Twin Air" $26, and

"Moose" $21. It sounds like most of you run the Uni, and some have had problems with the No Toil's not seating right.

What about the others? and are K&N's that much better?

The best air filter is a clean air filter. That said, I'm partial to Uni for the reasons already stated. I would not run a K&N on a pure dirt bike and I am one of those that dumped NoToil because of issues with fit.

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I have used K&N on everything from generators , lawn tractors , 2 strokes and 4 strokes , for my area i think they do a great job, properly oiled and cleaned they do well for me.

I ran 6 seasons with my present Xr before doing the top end , and it always had a K&n from day one.

Thats my take on K&n's

stu

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K&N's literature says something like, the dirtier they get, the better they filter. So is it better to keep them clean or dirty?

:cry:

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K&N's literature says something like, the dirtier they get, the better they filter. So is it better to keep them clean or dirty?

:cry:

Makes sense, dirt in the air being pulled into the filter would get trapped on top of the dirt already there, thus filtering the air through the dirt then the filter.

Now as far as your bike being able to breath with all that dirt on the filter, forget it, I want my filters to be clean and free flowing.

That statement within the K&N Literature would do nothing to convince me to buy their product, on the contrary I would question whether or not it filtered the air well enough when clean because that statement sounds like they would prefer you not clean it so as it performs at a higher level.

A clean and oiled UNI with the High Flow cage allows my bikes to breath well and perform well which allows me to have fun. :cry:

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I ran 6 seasons with my present Xr before doing the top end , and it always had a K&n from day one.

Thats my take on K&n's

stu

I vote for the Honda filter, and that's all I use. I found no difference removing the screen either. My '96 has 8 seasons on it and the original top end, my other '96 I bored for more power last year and the stock cylinder and piston were still like new when I took it apart.

That's my take on the Honda filter.

I used a K&N in my '92 XR250, but the latch design from '96 on for the filter sucks and IMO the K&N won't seat well enough. Honda should have used the pre'96 setup, but they didn't.

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Sorry to dissagree, but i hated my honda filter. I dont know about the UNI but the oem filter was like having a potato shoved in my pipe. I know K&N has given me performance for 5yrs. She was running better than new until i recently broke my shifter shaft. I guesse i can tell u what my cylinder looks like soon. :cry:

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i added a pc racing (i think that's their name) neoprene sealing gasket to the airbox where the filter meets it. it's about $10 and sticks to the airbox. this help to seal incredibly.

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Boatxr,

Do you have a phone# and a picture of it? It sound pretty interesting.

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I bought the K&N after dealing with the uni's and all that oily foam slime. Washing your hands three times gets old and i already have the cleaner and oil kit for the k&n so after buying the uni and the filter cleaner and oil the difference is only $5.00 and the k&n is very fast and easy to clean. I also bought the pc racing gasket so i should be set. Thanks for the input

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Sorry to dissagree, but i hated my honda filter. I dont know about the UNI but the oem filter was like having a potato shoved in my pipe. I know K&N has given me performance for 5yrs.

Well, maybe the OEM filter was over-oiled? Even if you are generous and say the K&N material has 50% better air flow per square inch, the K&N filter throws away half of the available filter area by having a tin lid over the whole flat oval part of the filter. THis also means that the air that does go through has to bend 90 degrees to match the direction of the airboot and carb. I can't understand why they did that. Kind of lame when it is advertised as a hi performance part, if you ask me.

The K&N I bought came with a foam gasket that was to be glued onto the airbox with its peel and stick type adhesive. Non-removable and non-transferrable. I have to agree with the other poster that the latch mechanism with the two metal wires going into the plastic stand-offs sucks and I liked the pre 96 setup better as well. The fact that the 1996 one would self-eject was a bit of an oversight as well, until they added the clip retainer to the lid... :cry:

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