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Discussion Starter #1 (Edited)
So I guess this is the wisdom I expect everyone ends up gaining after a few? years of riding and working on bikes, but I'm a newb with about 2 months under my belt and I'm late to the party.
To set the stage, it all started about 24 hours ago on a rabbit hole of video suggestions from YouTube. One of those moments where you watch one about slow speed maneuvering, which led to something about bimbos who ignore the ATGATT principle that end up biting it at 60mph. Before you know it, 2 hours have escaped you, all your laundry remains unwashed, you have no clean drawers for work and it's almost 1:30 in the morning.
Nevertheless, I found myself watching a video in which these engineers were testing different engine air filters using an elaborate computerized airflow machine. The winner being a filter I've never heard of and not presently sold in the US unless you ride a Harley or a KTM. The significance being, the Vulcan 900 OEM filter allows 78.35 cubic feet per minute of O2 and "DNA" brand filter allowing 163.8 CFM. Yes, you're reading that correctly; under this "scientifically" controlled experiment, the DNA filter demonstrates a 109% improvement in airflow vs OEM paper media. So down the hole I went, coming out where I am and wondering "so what". Does it really matter? If I'm not mistaken, isn't the engine filter supposed to prevent dirt and dust from entering the engine? Is it really a "performance" improvement so important that it warrants spending $35 in DHL express shipping from Greece vs $37 for an OEM filter? Has any of you well informed fellows ever used a DNA engine filter? I've searched the forum, but couldn't find anything informative. I'm also not sure where I stand anymore, but I do know this is the place where one should ask.

For what it's worth, the folks at DNA ship rather promptly and I received a tracking number in less than 12 hours; should arrive on Friday.
 

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The flow sounds good. A little over kill(not a bad thing) the motor needs about 100+/- cfm at 6000 rpm (max HP) and 120+/-cfm near red line.

For whats its worth, I run the K&N filter. About the same cost as the factory filter when I bought it. I have used K&N's for a long time on most all my motors. No adverse affects yet.

I believe the K&N filter flows 137+/- cfm new.

If a person is riding in real dusty area, might want a pre-filter.
 

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Discussion Starter #4
Thanks Rider50! I preemptively purchased a FI2000R assuming the big jump in O2 flooding the motor would cause it to run differently. Do you use a fuel commander with the K&N? Do you agree with my assumption that it will warrant a recalibration? Appreciate your feedback.
 

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Hey Rider50, how are you getting the air flow for the VN900 engine?

I am using these variables, as a starting place:

a) 55 cubic inch displacement
b) 7,000 RPM
c) volumetric efficiency (VE) of 85% (which would not likely be attained by this engine in stock configuration)

...and I get 94.69 cubic feet per minute of air moving through the intake.

A more likely VE for this motor (stock) is in the 75% to 80% range...so maybe use 77.5% VE...

So, then we get in the range of 86.0 cubic feet per minute of air moving through the intake @ 7,000 rpm.

Lets be optimistic and say the peak air flow required by the paper filter element is 90 cf/m.

Then one could assume that the stock Kawi air filter is a tad restrictive (if the spec actually says it flows 78.35 cf/m) at 7,000 rpm...while the new K&N is not...since the K&N flows (un-confirmed) 137 cf/m.

Will trading your OEM filter for a K&N unit require a "tuner" ?? Not according to this forum.

There is more going on an any given engine than what filter media is being used for the intake...and...is the OEM Kawi computer able to take into account these small changes in the intake air filter element type and flow rates and still provide a "usable" (or, maybe reasonable?) fuel/air mixture? Likely yes...as we have seen in real-life on this forum.
 

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This site is fun...if you like mathematics and engines:

Volumetric Efficiency (and the REAL factor: MASS AIRFLOW), by EPI Inc.

Also, check out "equation #6" which says:

REQUIRED AIRFLOW (scfm) = 2.723 x HP x BSFC

and we substitute in the values we know:

REQUIRED AIRFLOW (scfm) = 2.723 x (assume optimistically 60 HP at crank) x (BSFC best to use .48)

This the required airflow (scfm) = 78.42

All assuming 100% VE.
 

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I put the Cobra air scoop with the K & N filter. I didn't need a tuner till I changed the pipes.
 

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I used the Widman International web site. I assumed an efficiency of 100%. Better to assume the engine need more air than assuming it needs less.Their site states that some non "boosted" engines with FI/electronics may run at a higher efficiency than 85% some as much as 120%. I went with the 100% For a bit of fudge factor.

Yes I am running a Cobra FI 2000 tuner, I also have the air box opened up and Cobra 2-1 power pro HP's

I am with most others in that if you open up one of either pipes or air, you more than likely will not need to tune, if you open up both than a big YES.
Your results my vary.

Hope this helps
 

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Discussion Starter #9 (Edited)
Prenote: *This is intended for any newbie, with a stock bike, and looking for the cheapest and easiest upgrade. Like most people have stated elsewhere, every bike is different, and every bike responds differently to like mods.

I decided to ride around a couple weeks before leaving a follow up, to determine what I was seeing and feeling was perceptual vs. actual measureable change. I've gone through two tanks of gas, and despite "riding it like I stole it", my gas mileage has improved considerably. I'm fully aware every bike is different, but I believe my initial impression that the factory setup ran like ****, was precisely correct. For example, I would hit rev limiter for 2nd at 30, 3rd at 45, and 4th at 55-58. At 70-75 mph, the bike would shake, rattle and roll and leave me in the slow lane behind gravel trucks and semi's most of my commute to work. FYI, I live north of Dallas and the posted speed limit is 75 on the interstate. My gas mileage prior to install was 35-38 miles/gal.

With that in mind, I installed the DNA air filter and Cobra FI2000R. I installed at the same time, and plan on adding pipes later, however not sure if pipes are entirely justified at this point. I have fuel controller pot settings at 1.5, 1, 1. It starts and idles quieter and quickly transitions to slow idle in 5-6 secs vs. 30-45 secs before install. I have not noticed any discernible change in sound of rumble or acoustics of exhaust note. It runs "smoother" with less vibration at pegs and grips, regardless of speed.

I'm sure most of the improvements are result of the fuel controller, but I'm no longer riding in the slow lane. if shifting near rev limiter I can now shift at 40 for 2nd, 55 for 3rd, 65-70 mph for 4th. I can fully understand and realize why many others have stated they are no longer searching for 6th gear. It now pulls in any gear, regardless of where I am in RPM. It feels like im riding a "bigger" bike, or should I say, a well tuned motorcycle. I've not yet checked max speed, but I can attest that at 90, it runs just as smoothly as 60. The down side is, I find myself having to check my speed more frequently as I don't realize how fast I am traveling. Prior, I could "feel" my speed per vibration and engine sound; most of which, has disappeared entirely. I find myself wishing for sound, as it may have been a false sense of security in terms of visibility. My mileage is now running between 48-50 miles/gal, as others have reported. I'm truly over joyed with the outcome. It's now become more obvious how uncomfortable the stock seat is and I plan on fixing that problem soon, as well. Hope this helps anyone interested.
 

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Thanks for the up date "BigTexMike900CA"

Unless things have changed, the limiter kicks in at or near 37-40mph in first. At least on my 07LT with me on it. That and mine still takes a minute or two when cold(sub 70's) to idle down.

But glad to hear your bike is running more in line with how you want it.
 

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I am with most others in that if you open up one of either pipes or air, you more than likely will not need to tune, if you open up both than a big YES.
Your results my vary.

Hope this helps
Mmmmm? so if I add a K&N air filter on my bike that has debaffled pipes. ( love the sound) I might need to tune it?
 

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Discussion Starter #13
Honestly having put one on, I'd say absolutely yes. I personally think every bike should have one installed, regardless of what they do to with the air exiting the engine.
 

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Any noticeable difference with the scoop ? Nice look by the way.
Thanks, Lots more air into the engine so I feel more power. After I added the new pipes I took it to my local shop and had them put it on the Dyno. Just want them to dial it in. Runs great, I get a little popping at times but not bad. I just ordered the screen in black (17 bucks) to give it some contrast.
 

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Mmmmm? so if I add a K&N air filter on my bike that has debaffled pipes. ( love the sound) I might need to tune it?
Chances are good that you may need one. Did you open up the air box, or just put in a K&N replacement filter? If just the filter, then maybe a 50/50 chance, as the inlet for the air box is just enough for a stock flow. The controller settings would be set fairly low. 2-4% or less of possible enrichment. Most setups only use 7-10% with most of that coming in at idle to 2K rpm, On the Cobra tri pot type. Your motor and setup could be different of course.
Just my .02
 
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