Air filter opinions pleeze!

[Redbird]

The reason your bike ran worse at the Higher RPM's and at the Higher altitude was because you were starving for fuel... not air

Then why was it better at lower elevations, where there's more air?

[jrdxx]

K&N's test procedure utilizes a flow bench in a controlled ambient environment, which would eliminate most variables (even back-to-back dyno runs can vary due to ambient weather conditions, motor temperature, etc.), and is well documented on their website. Users have to understand their baseline conditions. If the bike in stock configuration already runs like crap, the addition of a K&N filter won't magically improve performance unless the source of the mistuned condition happens to be a clogged air filter. If the mistune is in another area, the addition of the filter could indeed make the bike run worse, and lead to a mistaken assumption that the filter is not flowing more air.

All other things being equal, the addition of a K&N filter to an otherwise stock blackbird would likely have a negligible effect on performance, mostly because the engine is a balanced system-balanced between the volume of the intake airbox on the one side, and the exhaust system on the other. Any gain in airflow is negated by the backpressure of the exhaust. The same thing happens on the other side-an aftermarket exhaust on an otherwise stock blackbird will make more noise, but without other modifications not necessarily make more power.

A stock carbureted engine tuned to sea level will run richer with increases with altitude. If the intake filter is changed and (possibly) the exhaust is modified, that makes for three variables. Rejet the carburetors, then tell us how the bike runs.

[Involute]

The reason your bike ran worse at the Higher RPM's and at the Higher altitude was because you were starving for fuel... not air

Then why was it better at lower elevations, where there's more air?

Don't you know that at higher elevations there is less fuel?

Thats why Jumbo Jets need to carry so much with them. :mrgreen:

EVLXX, I think your barking up the wrong tree here. Sorry Bub.

[bartonmd]

Yep... a bike runs richer at higher altitude because it's flowing the same amount of fuel, but there is less oxygen up there to burn with the fuel...

Mike

[EVLXX]

Fuck.... Already typed a great big long reply and then got dumped.

Not doing it again.

Mike and Tim... you are correct in the fact that I should not have typed the elevation and air flow comment in the same sentence.

Increased air flow through the filter = leaner mixture, so you have to Fatten the mixture a bit.

Increased elavation / less oxygen = richer mixture, so you have to adjust by leaning the carb a bit.

Go study carberation again... I'm not teaching it right now. Sorry.

PS... Merrry Christmas eve to you too.

[Redbird]

Go study carberation again... I'm not teaching it right now. Sorry.

Good thing, seeing how you can't spell it. Do me a favor, don't treat me like an idiot and I'll return the favor :wink:

Now, explain to me how a lean running condition was worsened by an increase in elevation and I'll shut up.

[shovelstrokeed]

For the most part this is totall Bull and should be disreegarded. I especially would NOT recomend starving your Mototr of Air with a piece of Saran wrap.

And the reason you have never seen a Dyno back to back is becasue the power increase is minimal.... the major advantage is in the reusability. And considering the amount of road dust around here in the spring.... I make up made my money back real quick.

How is it bull. They don't, by your own admission flow enough more to show on a dyno. Hence, HP increase claims are dubious at best. The reusable thing comes at the expense of filtration efficiency so you wind up with more crap in your engine. The Saran Wrap thing was done on the BMW board and they found no HP drop with 50% of the fliter blocked. It may be possible that a 'bird needs all of the fliter area availabe but, I doubt it. Pleated paper filters have huge surface area and are made with smaller holes. The likelyhood of you clogging your stock air filter is, of course, directly related to the enviornment in which you ride. Given that you might have to change every 12K miles or so, you might have sound reason to go with a reusable filter. My point was that one should not expect a HP increase as the K&N advertising touts.

[shovelstrokeed]

For the most part this is totall Bull and should be disreegarded. I especially would NOT recomend starving your Mototr of Air with a piece of Saran wrap.

And the reason you have never seen a Dyno back to back is becasue the power increase is minimal.... the major advantage is in the reusability. And considering the amount of road dust around here in the spring.... I make up made my money back real quick.

How is it bull. They don't, by your own admission flow enough more to show on a dyno. Hence, HP increase claims are dubious at best. The reusable thing comes at the expense of filtration efficiency so you wind up with more crap in your engine. The Saran Wrap thing was done on the BMW board and they found no HP drop with 50% of the fliter blocked. It may be possible that a 'bird needs all of the fliter area availabe but, I doubt it. Pleated paper filters have huge surface area and are made with smaller holes. The likelyhood of you clogging your stock air filter is, of course, directly related to the enviornment in which you ride. Given that you might have to change every 12K miles or so, you might have sound reason to go with a reusable filter. My point was that one should not expect a HP increase as the K&N advertising touts.

[EVLXX]

Go study carberation again... I'm not teaching it right now. Sorry.

Good thing, seeing how you can't spell it. Do me a favor, don't treat me like an idiot and I'll return the favor :wink:

Now, explain to me how a lean running condition was worsened by an increase in elevation and I'll shut up.

Yes Tim... I know I can't spell for shit... and I don't care about spelling all that much anyways. I care more about the actions than the words.

I also type with two fingures so trying to type faster leads me to alot of misspelling, because my thoughts get way ahead of the sentence I'm on.

But back to your point....

if you'll note above, I said I should not have put the 2 in the same sentence. Elevation (less oxygen) and Higher RPMs (Filter flow). The 2 both have different effects on the motor.... but my point was that ...

Not haveing adjusted the carburators propperly before he went to the high elevation just gave him more problems.

The filter fucked up his High RPM mixture... I'm sure...

and going to the higher elevation screwed with his Low and mid range.. making everything seem worse.

And lastly.... all of this bickering doesn't mean shit, because both of us have to ASSUME we now exactly what he was experiencing.... and we don't.

I'm was just try to throw out there what I now about what happens when you remove an air filter restriction on a carberated motor.

[EVLXX]

For the most part this is totall Bull and should be disreegarded. I especially would NOT recomend starving your Mototr of Air with a piece of Saran wrap.

And the reason you have never seen a Dyno back to back is becasue the power increase is minimal.... the major advantage is in the reusability. And considering the amount of road dust around here in the spring.... I make up made my money back real quick.

How is it bull. They don't, by your own admission flow enough more to show on a dyno. Hence, HP increase claims are dubious at best. The reusable thing comes at the expense of filtration efficiency so you wind up with more crap in your engine. The Saran Wrap thing was done on the BMW board and they found no HP drop with 50% of the fliter blocked. It may be possible that a 'bird needs all of the fliter area availabe but, I doubt it. Pleated paper filters have huge surface area and are made with smaller holes. The likelyhood of you clogging your stock air filter is, of course, directly related to the enviornment in which you ride. Given that you might have to change every 12K miles or so, you might have sound reason to go with a reusable filter. My point was that one should not expect a HP increase as the K&N advertising touts.

Yes by my own admission they don't always show a noticable increase on the Dyno.... but they DON"T show a decrease at all. So the company is totally correct in stateing that they can unlock more HP.... or what ever it is they say like that.

Now as for my experience... before I had a K&N... my buddy on his BUSA would out pull me on the top end every time. I would either never catch him or he would walk away from me.

Now after installing the K&N, putting on a set of Yoshi's, removeing the PAIR unit, and doing my own mapping....

I can just slowly out pull him! No SHIT! I walked by him at about 170 ish somewhere in the middle of Nevada. So..... that would lead me to believe that the K&N helped to unlock some extra HP.... wouldn't you ?

And one more thing.... Saran rap and a BMW... well... ... need I say more. Well OK... maybe Saran wrap could help them win a Major motorcycle championship...... NOT! And I wouldn't call "seat of the pants", Dyno testing, or scientific by any means.

[EVLXX]

Do me a favor, don't treat me like an idiot and I'll return the favor :wink:

I wasn't trying to treat anybody like an idiot. Especially you Tim.

.... see this goes back to one of those post were I stated I hate getting IN TO IT, because I know my word smithing is is not the greatest, and sometimes it's down right horriable.

So I sometimeshave a hard time communicating what I'm thinking.

Goodnight !

[pug]

I am using K&N filters for more than 10 years in my vehicles and I would say that there is a difference, especially in roll-on acceleration. Not a day-night difference but a noticeable one.

Saying that I have to add that on the XX the gains were minimal (maybe crisper throttle on high revs), but I cannot be objective because my conclusions are based on the days I ride the bike with stock filter (when servicing the K&N and waiting to dry for a couple days)....... and I already have free flowing slip-ons (Termignoni's) and a custom mapped PC3 for this setup.

I think that I prefer the K&N because -being raised with dirt bikes- I feel better when I clean regularly and oil my air filters.

By the way has anybody of you notice that the OEM filter is a heavy duty item (with the wire mesh on the intake) which fits perfectly on the airbox (not like the K&N) and comes already OILED (first time I see this on a paper air filter) ?

[shovelstrokeed]

Chris,

Given your experience I would say you did well with the K&N. The question remains is whether or not the filter contributed or was it the other mods that added the HP. Back to back runs against your friend with the K&N and with the stock filter would be the only way to be sure. Honda's pricing would certainly make the K&N more attractive over the long run.

Pug,

Oil and paper filters don't mix at all, unless there is a foam component above the paper filter. In fact, any liquid and paper filters is a bad idea.

The title of this thread is "Opinions on air filters". I have voiced mine.

[Involute]

The details of my experience are pretty much all there. I can add:

After I installed the K&N the bike felt a little sluggish all around but at higher revs is stumbled pretty bad. At higher elevation the stumble came on a little earlier and more pronounced. At a certain RPM at full throttle the bike basically stopped pulling and just made noise. If I recall correctly at lower elevation it hit at about 8000 RPM. Up higher around 7000. I put the stock filter back in and all was fine at all elevations.

I'm reasonably sure the bike has never been re-jetted. My home elevation is about 4500.

I've been very happy with K&N Filters. I've never had an experience like this with them before. I've but them in my KLR 650 and Concours within a month of getting them out of the box and they helped a lot. I immediately noticed the bike was breathing better. I did not re-jet either bike. I liked what it did to an XR600. I've had good luck with them in cars also.

Based upon my experience and limited knowledge the stock XX filter flows better than a K&N. Until someone can convince me I'm wrong I'm sticking to my opinion. I am not an expert of any kind. I am just basing it upon what we all know. Which is the air is thinner at higher elevations. The only variables I had were 2 air filters and different altitudes. Same day, same ride, same tank of gas, same wrist whacking the throttle WFO and holding it there.

Merry Chritmas all of you. Now get off the computer and go hug people you love. Thats what I'm going to do. :wink:

[Redbird]

I wasn't trying to treat anybody like an idiot. Especially you Tim.

This is the statement that kind of rubbed me the wrong way, just so you know-

Go study carberation again... I'm not teaching it right now. Sorry.

The inference being that Mike and I need to learn a thing or two, while you're some master who's not in the mood to impart any of his wisdom to us at the moment. You may not have meant it that way, but that's how it came across. I know you're not an asshole or my response would have been even more pointed. Water under the bridge, as far as I'm concerned.

That said, I certainly make no claims to being an expert on carburation. Can't tell you how happy I am to own an FI bike, I hated dicking around with carbs, especially on multi-cylinder bikes. Only carbed bikes I ever felt totally comfortable tuning have been single cylinder dirtbikes, two or four stroke, don't care, it's easier than a bank of the things.

So, this is an exchange of opinions, done politely and without disparging anyone else's level of knowledge maybe everyone can learn something, like does a K&N really flow more air than stock? If it does is it enough to make any difference without other signifigant mods? I've seen no proof from anyone other than K&N that their filter moves more air than a clean stock XX filter. Anecdotal evidence such as yours means nothing, there were other mods to your bike and your baseline for comparison was another bike, which could have been having any number of issues itself. The XX gives up 20+ HP to the Busa, so if you pulled him at 170 I would sooner assume there was something wrong with his bike than give credit to an airfilter.

Scot's experience would seem to indicate the K&N resticted flow from what I know. Less air, rich condition, worsened by an increase in altitude. Yes there's other variables and it may not be that clear cut, but if a bike is running lean and you give it less air, it gets better, not worse. No one has explained to me how the reverse can be true- and I'm listening if you want to make that clear to me. This isn't a "bullshit, you're wrong" type of statement, it's a "please point out the flaw in my logic" type of statement. And again, it's more anecdotal evidence, anyway. As Scot said, it may have been as simple as the thing was over-oiled from the factory, and it's one guy's experience on one bike. But I wouldn't dismiss it out of hand like you seem to want to do.

Bottom line is I'm not sold on K&N being any kind of performance upgrade on the XX. Re-usability, yes, but I hate "servicing" airfilters, so I'll stick with the stocker myself.

[Warchild]

On most every bike forum on the 'net, the discussion of stock vs reusable air filters has gone the way of discussing the best oil, the best tires, the best chain lube, etc, etc. This debate is as never-ending as it is pointless.

That being said, I'll offer up my non-dynoed, anecdotal, actual real-world experience having used the K&N on my Blackbird for just shy of 6 years/75,000 miles: it works just fine.

And I've never had to buy the spendy paper air-flter once, not since I rolled the bike off the showroom floor.

I use the K&N for strictly for the maintenance longevity aspect, vice any perceived/actual performance gains.

[pug]

Oil and paper filters don't mix at all, unless there is a foam component above the paper filter. In fact, any liquid and paper filters is a bad idea.

I know that and thats why I mention what I observed. The stock filter I bought certainly had a thin layer of oil. Might have been a preseervation oil or whatever, I can't tell. Because it felt very strange, after reinstalling the K&N, I washed the stocker (I do it the foam filter way) and afterwards I oiled it. It was still reusable, the paper layers did not collapsed but a 'wave' was formulated. Maybe the porous were clogged, but I do not have a Superflow rig to test it. By no means I am not saying that you can treat the stock filter like a K&N, all I am saying is that it didn't disintegrated like I was expecting.

I use the K&N for strictly for the maintenance longevity aspect, vice any perceived/actual performance gains.

I think the above summarizes all perfectly.

Merry Christmas and a Happy New Year with no accidents for everybody .

[EVLXX]

Scot's experience would seem to indicate the K&N resticted flow from what I know. Less air, rich condition, worsened by an increase in altitude. Yes there's other variables and it may not be that clear cut, but if a bike is running lean and you give it less air, it gets better, not worse. No one has explained to me how the reverse can be true- and I'm listening if you want to make that clear to me. This isn't a "bullshit, you're wrong" type of statement, it's a "please point out the flaw in my logic" type of statement. And again, it's more anecdotal evidence, anyway. As Scot said, it may have been as simple as the thing was over-oiled from the factory, and it's one guy's experience on one bike. But I wouldn't dismiss it out of hand like you seem to want to do.

Bottom line is I'm not sold on K&N being any kind of performance upgrade on the XX. Re-usability, yes, but I hate "servicing" airfilters, so I'll stick with the stocker myself.

Well... here I'll try...

Good morning Tim...

First off you have to think of air as being elastic, stretchable, compressable, etc. Fuel on the other hand is not.

The first part of a carberator works, by increasing the speed of the air through the bore or mouth of the carberator, this also creates a small pressure rise in this area, which can be parcitially directed into the float bowl buy the pilot jet.

The second part of the carberator is the throat, were it gets bigger. As the air fills this bigger area, it wants to slow down, but can't. So it creates a pressure drop which is what grabs the heavy fuel and carries it along into the intake tract.

But there is the whole problem with tunning carberators, that low pressure varies all the time. It changes with every RPM the motor increases and in also changes with how much air pressure is pushing on the mouth of the carberator.

Every air filter is a restictor plate to some degree.

But back to the problem, so as you increase the amount of air pressure on the mouth of the carberator, and increase the amount of air that goes through the carberator, create create a greater Low pressure difference in the throat. Now at first one would think that it would then grab more fuel... because it has more suction. But that's not always the case. If the carberator was tuned properly to start with it will cause an even greater lean out, because the Jets are not going to allow any more fuel to pass through to get picked up.

So... I'm guessing (which I hate to do, but I will) that Involutes bike was never propperly tunned in the first place. which means his fuel ratio is already off for his elevation. So maybe this is where I probably screwwed up in the first place... I was assumeing... I should do that... I don't know if his bike is running rich or lean.

Now if his Jets were original too big for his elevation... then the oposite will occure and the motor will go too rich. It's a good rule of thumb to drop one jet size for every 2,500 feet of elevation. Since he is running at almost 5K feet, he is already running jets 2 sizes too big, if he still has the stock jets in, and probably already running a little rich.

Tunning carberators is not always fun, because first you must tune it propperly for it's conditions, elevation, motor, RPM, Baro, humidity, etc....

then you must tune it again for any changes you make in terms of Mods., exhaust, air cleaner, cam, etc.

As for Involute... you have one more test you could do....

but first off you need to get your bike adjusted for it's altitude, then...

on the same day...

1) Run the bike with the stock air filter.

2) pull it and put the K&N in, run it and notice any change.

3) remove the air filter all together, run it and see if it feels more like with the stock filter in... or more like with the K&N in.

If running without a air cleaner feels more like stock then you could conclude that the K&N is restrictive.

But if running without the aircleaner feel more like running with the K&N, then you could coclude that the stock filter is more restrictive.

Now.... I have seen the diference in flow on a makeshift flowmeter, between the stock and K&N filter, and can tell you the stock filter is alot more restrictive.

I hope all that helps... ?

PS. Tim... I'm also glad and pist at the same time, that I have a FI bike. Glad because I don't have to pull the bike apart in order to adjust the fuel, as I did with carbs.

But I'm also pist because I had to spend an extra $600 too be able to propperly adjust the FI system. :wink:

So just remember air is elastic.... and that changes everything.

[EVLXX]

And I've never had to buy the spendy paper air-flter once, not since I rolled the bike off the showroom floor.

I use the K&N for strictly for the maintenance longevity aspect, vice any perceived/actual performance gains.

Same... except I do want any of the performance increaes I can get.... however big or small they may be.

[EVLXX]

I wasn't trying to treat anybody like an idiot. Especially you Tim.

This is the statement that kind of rubbed me the wrong way, just so you know-

Go study carberation again... I'm not teaching it right now. Sorry.

The inference being that Mike and I need to learn a thing or two, while you're some master who's not in the mood to impart any of his wisdom to us at the moment. You may not have meant it that way, but that's how it came across. I know you're not an asshole or my response would have been even more pointed. Water under the bridge, as far as I'm concerned.

For the record...

Yep.. I see your point.. and I'm sorry... I didn't mean it that way... just meant I didn't have the time right then.

Water under the bridge, Yes.

We are all learning every day... sometimes we stumble, but the important thing is we continue on.

[EVLXX]

Oh and one more thing...

when someone is talking about how the bike is running, or when I do...

and they say it's stubleing or hesitant... I think Lean. Because Lean is a lack of propellant.

and if they say it's sluggish or boggy... I think Rich. Because then it has too much fuel, and has a hard time swimming out of the excess.

Lean feels like... it doesn't have any more power. It stubbles it hesitates, it misses, because it has nothing left to give.

Too Rich feels like someones grabbing the brakes. It's fat, it's slow, it's ate to much and doesn't want to go any more. :wink:

Maybe there was some confusion earlier because of my interpritation. :?

[EVLXX]

OK... just learned something...

my old thought was that air going from a small tube to a larger tube created a lower pressure in the larger tube because of the increased area.

I used to think the low pressure was after the throat so's to speak... and that the vacume was created there and that it drew the fuel from there.

Wrong...

Just reread, and learned it's the accelerating air in the smallest part of the tube or throat that has the lowest pressure.

Still doesn't change the above notes about the fuel and jets though... actually it reinforces it.

Still learning over here.

[REXX]

The details of my experience are pretty much all there. I can add:

After I installed the K&N the bike felt a little sluggish all around but at higher revs is stumbled pretty bad. At higher elevation the stumble came on a little earlier and more pronounced. At a certain RPM at full throttle the bike basically stopped pulling and just made noise. If I recall correctly at lower elevation it hit at about 8000 RPM. Up higher around 7000. I put the stock filter back in and all was fine at all elevations.

I'm reasonably sure the bike has never been re-jetted. My home elevation is about 4500.

I've been very happy with K&N Filters. I've never had an experience like this with them before. I've but them in my KLR 650 and Concours within a month of getting them out of the box and they helped a lot. I immediately noticed the bike was breathing better. I did not re-jet either bike. I liked what it did to an XR600. I've had good luck with them in cars also.

Based upon my experience and limited knowledge the stock XX filter flows better than a K&N. Until someone can convince me I'm wrong I'm sticking to my opinion. I am not an expert of any kind. I am just basing it upon what we all know. Which is the air is thinner at higher elevations. The only variables I had were 2 air filters and different altitudes. Same day, same ride, same tank of gas, same wrist whacking the throttle WFO and holding it there.

Merry Chritmas all of you. Now get off the computer and go hug people you love. Thats what I'm going to do.

I had the EXACT same experience as you...except add in HORRIBLE fuel mileage! All I got was a lot of "intake noise" with the K&N that makes you think you're hauling ass, but my "ass dynometer" told me different. My fuel mileage dropped around 8 mpg on top of the shitty performance. I was so pissed that I emailed K&N about their bullshit claims...no response. I would also be willing to bet that the K&N filters WORSE than stock because of all the "dust/dirt" I found in the air box when putting the stock filter back. Once the stock filter was put in place mileage and power returned. I will say that I use a K&N on my 94 Formula and it gets better mileage and performance, just like advertised. I can only attribute this to maybe a computer that "recalibrates itself"...I don't know? I have read here about people that use a K&N in conjunction with a Power Commander that allows them to make the necessary A/F changes to gain increased power. So K&N needs to add another sentence on their advertising..."Must purchase $250 Power Commander and arrange $200 dyno session to gain your extra 3 HP".

[EVLXX]

OK... you ready for this...

Once again I have been down a path.... and have been turned around.

I must have been asleep in shop class the day we were doing carberation... or maybe it was the air I was breathing just before shop class... :roll:

Anyhow...

I've been reading...

Learned to things... 1. that the air flowing throught the carburetors is at it's lowest pressure when it's going throught the smallest part of the bore.

And that the air does not compress as it goes into the Mouth, so there's no pressure increase there either, that actually happens after the carburetor when the bore or intake track gets bigger... then you have more pressure.

2. The more air you flow through a carberator... the Richer the fuel mixture will get. It's a velocity thing, the more air you flow throught the same size hole or bore... the faster it has to go. Which creates even low pressure, so it picks up even more fuel, more fuel than it should.

Yes air is elastic, and it's like takeing a wet rubberband and makeing a mark on it with a permenant pen every inch. The more you stretch it, the more narks you can put on it... but it's still the same volume of rubberband.

So Involutes bike.... must have been way way way too Rich. Which would also explian it getting worse at a higher elevation.PS. which would mean that the K&N was flowing more air... :wink:

[shovelstrokeed]

Eric,

You sure about that logic in re the K&N flowing more air?

Assuming the bike is a bit rich. It will get richer at higer elevations and likely run worse. If it is running worse with the K&N installed as well and gets better with the stock filter in place the K&N would be suspect of richening the mixture as well which means less air not more. More air would tend to lean it out and should have improved the situation.

What I think poor Involute, who has by now gone out and bought an EFI bike, encountered is a mis tuned motor, already too rich and and over oiled K&N which presented further flow restriction and thus made the rich condition worse.

Proper steps for correction, as have already been pointed to, begin with getting the jetting right at baseline altitude. If the bike is jetted for sea level it most certainly will be too rich at 4500 feet. Heading uphill from there is bound to make it worse.