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Discussion Starter #1 (Edited)
There seems to be unnecessary/undue/excessive criticism in my homemade air filter thread, so I wanted to discuss filters in general.

Whether it be oil, fuel or air filters, in all cases they are a compromise between removing unwanted/harmful particles, and restricting flow to the point that they are doing more harm than good.

Two general statements about filters are:

* Large particles are harmful, and
* Small/minute particles are virtually harmless

Also, the mechanics of filter are such that a brand new filter actually filter less than an older/dirty/clogging filter. The reason: older dirt in a filter actually assists the filter media in trapping new dirt. You can see this by holding a brand new filter compared to a dirty filter up to a light and seeing how much light gets through each.

The bottom line is that a filter's precise micron capability is NOT all that critical; you just need to make sure that you have enough filtering capability that you are removing large to medium size particles, without removing such small/minute particles that you are restricting flow, or that the filter will clog in 10 minutes of use and have to cleaned/replaced before continued use, and I am confident that my homemade filter design fits the bill. :):):)



 

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Old Twistie Sticks Rider
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If you have rode dirt bikes much, there was an old trick that we did, and I still use it on my mowers & cycle... If you have room (You usually do) rub some stiff grease on the insides of the filter cover, you won't believe what will be caught before going to the filter...
Be careful to not get any on the filter itself though... Remember this is not clogging your filter... You should see my mower filter cover when I clean the filter, there is a minimum of 1/4" of dirt on the inside of the cover...
Have a good one...Old Dog...
 

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First, you could have put this post in the thread you already started instead of starting another one.

Or you could have at least put this one in the proper section.... as you did not do with the other one ...

That all aside... You cant just judge the filtering qualities of a media by how much light passes through it. A sheet of glass passes alot of light and zero particles....

That aside.... I am sure your homemade filter is better than no filter at all and may even be more efficient at removing " harmful " particles than the stock filter.

But you have no testing data to share other than your seat of the pants opinion. Sorry, but not sure I'd trust my engine on some homemade untested filter...and that was what my point was in your other thread.

If you trust your handiwork that the filter material is strong enough to last or that your glue job will hold...good for you.

Size of the dirt that enters the motor matters less than what it is made of. See you live in Florida....fine sand will do more damage to your motor than stuff like hair or organic matter like pollen, leafs or bird poop dust.

Again, not saying your filter does not work, just saying it's an untested unit and I wouldn't feel comfortable using it. If you can't afford to buy the needed parts for your bike I guess that's another thing entirely.....
 

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Linkmeister Supreme
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Discussion Starter #5
fine sand will do more damage to your motor than stuff like hair or organic matter like pollen, leafs or bird poop dust.
Large particles of sand are the ones that actually can cause wear in an engine. I have all the confidence in the world that my filter design blocks them. If the very small/minute particles of sand do indeed pass thru my filter, they do not have enough mass to be of consequence. There is no such thing as a 100.000000000000% efficient filter on any kind. :smiley_th



 

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Old Truck Junkie
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You will probably be safe in Florida with it. Here in West Texas where one can get caught in a bad dirt storm where sometimes even the road is hard to see, well I am not even sure if the oem filter can accually filter all the dirt out.
 

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There is no such thing as a 100.000000000000% efficient filter on any kind. :smiley_th

Actually there is. There are several types of filters that can remove 100% of fine particles from the air. (and 100% is a defined limit, there's no reason to add a decimal point and more zeros...)

The problem with over efficient filters is they aren't that nessesary on a internal combustion engine, and that they can't filter large volumes of air without being uselessly large. There's no need and no room for a filter that's bigger than the motor it's protecting, especially on a motorcycle where space is limited.

Anyway, if you're happy with your creation that's all that matters. I'll keep using filters specifically designed for my bike as they are tested , warranted , and I don't have to any other work besides just switch them out every X amount of miles if needed.

And I'm not sure your statement that a dirty filter works better than a brand new one is 100% valid. You have any research on this?
 

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Discussion Starter #8
If we are discussing which filter removes more dirt, then the dirty filter does. As the filter media captures dirt, the pores through it begin to plug up. As these pores get smaller and smaller, they are able to capture particles that would normally go right through the clean filters larger pores, which results in better filtration. There will be a balance point where the restriction of the filter will become to great and will start to affect performance. Typically this is when the restriction reaches 25" of water column. if is virtually impossible to service/replace an air filter without letting some dirt into the engine, which is why many engine manufacturers recommend that over servicing of air filters be avoided.
One of the things that we often forget is that an air filter is usually sized to deliver adequate airflow with minimal restriction for the greatest amount the engine will need, wide open throttle at high rpm. How often do we drive like this?
 

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........
One of the things that we often forget is that an air filter is usually sized to deliver adequate airflow with minimal restriction for the greatest amount the engine will need, wide open throttle at high rpm. How often do we drive like this?
Some of us.... Most of the time. ;)
 

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..have a vulcan good day!
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Old Twistie Sticks Rider
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Some of us.... Most of the time. ;)
Yep, absolutely & that's why I paid out the yo-yo for that 3 yr. extended warranty...
Have a good one...Old Dog...
 

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If only it had 6th gear..
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I often have her at WOT or close to it :smiley_th.
 

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..have a vulcan good day!
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It is my belief that an air filter is NOT a compromise, that it's one and only job is to stop any and all particles from entering the engine. While this may or may not be possible, you should at least get as close to it as you can, which I believe a well oiled stock filter with grease on the flange part of it that fits against the back of the filter housing does. On street operated vehicles, an air filter is most definitely NOT a tuning part. The Vulcan 750 was designed by Kawasaki to run with oiled stock filters, and it was jetted for them. And even if I do say so myself, it runs pretty darn well. It outruns cruisers twice it's size. What more do you want? It is also my belief (and I have plenty of evidence to back this up) is that a filter that flows more air also flows more dirt. Dirt is BAD for any engine, and the ideal thing would be to keep ALL dirt, even the tiniest microscopic particles, out of it. Or that is at least what you should shoot for. Anything less is going to reduce the longevity of the engine. Tiny particles you cannot see are not going to cause catastrophic engine failure. But they do cause engine wear, and who knows how many miles they will knock off the life of your engine. Unless an engine is used for racing, and you accept the consequences of that, the intake should be left stock.

All the aftermarket air filters I have seen, except Emgo, which I use, and which clearly say "meets all stock specifications" right on the box, use high flow, flows more air, high performance, etc. as a major selling point. And those are exactly the things you DO NOT want in an air filter. I have yet to see an air filter that says it actually "filters" better than stock. If such a filter were made, and the claims substantiated, I would buy it. Would you run non detergent oil in your engine, or go 20,000 miles between oil changes? Probably not. But yet you are willing to use a filter which will allow a lot more dirt into your engine, either to save a few pennies, or to try and gain a 100th of a hp. That's pretty much all I have to say on the subject.
 

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Old Twistie Sticks Rider
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/\/\ I basically agree with what KM & Jerry are sayin... About the only way to better the OEM filter is to go bigger, then to realize more HP you have to Mod. the exaust for more free flow or you still haven't done anything to speak of... Perhaps that is why the vn750 has 2 filters, very few bikes do...
Have a good one...Old Dog...
 

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I was waiting for Jerry to chime in here. I do need to point out that the filters K+N make for motorcycles are sometimes different than the ones they make for cars.

Most cars come with pleated paper filters. The Vulcan uses open cell foam. If you use K+N replacement filters in the Vulcan, you do not need to rejet.

This tells me they are not "flowing more air" than the stock units. The K+N filters you clamp right to the carb mouth when you do an earshave do flow more air as they are sold as "performance" filters.

ALOT of this increase in air is also do to just removing the pounds of plastic duct work the stock bike has.

If you take the replacement filter apart and flatten out the pleated paper, you'll get a few feet of obvious surface area. If you triple or quadruple the surface area of a filter, you can get higher airflow........without increasing the amount of crap that gets through the filter.

Thus makes Jerrys statement invalid that " if you get more air flow, you get more dirt"

In short, I believe the K+N replacement filters that fit in the stock airbox actually filter dirt better than stock, and that the K+N pod filters many use in an earshave do not. They have a smaller surface area. The stock airbox by design also causes the velocity of incoming particles to slow due to the right angled turns it they have to go through before hitting the filter. Not sure how much this helps however.

The OPs homemade filter looks thin and I can't see how it has more surface area than a pleated design. Foam is not a real good filtering media, but is cheap and easy to form. Am not sure exactly what material those vent filters are made from. I've seen simular "filters" made from nylon...like those 3M scotchbright pads you can sand with. I'll tell you right now that stuff makes a lousy filter. Foam and paper work well because they are soft porus material and dirt "imbeds" in them better than plastics. Foam works better if it's oiled.

Kawasaki did not design the filter to flow all the air the motor needs at WFO..... But to flow the amount of air they WANTED the motor to get. Anyone that's done an earshave knows the motor can take more air, and to even this out that's why you need to rejet.

If having the bike out live you is important, don't alter it. Keep it stock and use the replacement filters. (if you believe Jerry, don't use the K+N filters)

If you want a bit more power or just want the bike to look or sound different, and really don't care if the bike lasts for 180,000 miles, do what you want. Have fun. That's what bikes are for.
 

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Old Twistie Sticks Rider
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/\ KM I love that last part, " Have fun. That's what bikes are for." you hit the nail right on the head...lol...
I did a bit of mod. on my SE filter which is a bit over stock to start with, and then opened the SE exaust a bit to go with it... I could tell a difference (seat of pants) in increased performance & a slight bit of decrease in gas milage... BTW-I have seen 7,100 RPM on the tach, you don't see that on many Sportsters... (I turned chicken when it passed 7K)...lol...
The mod. was from the SE filter on the bottom to the K&N on top...



PS-This is on an EFI bike so the re/jetting don't apply...
Have a good one...Old Dog...
 

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KM makes one good point. On cars, you can use the SAME pleated paper filter as stock, only instead of having it completely encased in a round metal container (I'm talking about old cars here) with one small snorkel attached to it, you can install it without that container, with nothing but a metal top and bottom plate for the rubber seals on it to seal against, leaving the ENTIRE filter exposed. You will get more airflow (I used the word "more", because "more" is not always "better", which I believe to be true in the case of the Vulcan) without more dirt, because you are still using a stock filter. IMO, this option is even better at filtering than putting a K&N into that big metal container (the air cleaner housing assembly), because (also IMO) the K&N filter will always flow more dirt, because it is more porous than a stock filter (both well oiled. A foam filter of any kind is almost worthless without oil. It is the oil the does the filtering, not the foam) but the more surface area you have, in other words the thicker and denser the foam is, the more oil it can hold, and there is more oily foam to hold the dirt.


I stand behind everything I have ever said about K&N air filters, because there is almost overwhelming evidence to support my beliefs, not only online, but ask almost any long time mechanic, or racer, and they will tell you the same thing. K&N makes racing filters, for use on vehicles where you already know the engine is not going to last forever, and you are sacrificing engine longevity for speed. If that filter helps you win the race by 1/100th of a second, then it did it's job. But the job of an air filter is vastly different (actually completely opposite) on a street vehicle.

As for the Vulcan's ears, which I actually like, though I do wish they were styled a little differently, I believe there are 2 of them for cosmetic reasons only. Compare the size of the little square hole on the back of the ears to the size of the duct that connects the ears to the surge tank. Those ducts have the ability to flow more air than what can get through that little square hole. It would have been easy to design the system with only one filter assembly, and still have the same airflow. In fact, it looks like they made that little hole so small (and then put that rubber grommet in it, which I did remove) to PURPOSELY restrict airflow, so they could use a second air filter on the other side and still have the airflow they wanted.
 

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Old Twistie Sticks Rider
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/\ Don't forget that the velocity of the air thru the filter will cause more contaminants to pass thru the filter, that is one reason that more is better IMO...
Have a good one...Old Dog...
 
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