K&N air filters - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 17 (permalink) Old 10-11-2011, 01:03 AM Thread Starter
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K&N air filters

It has always been my contention that K&N filters not only do not increase HP, but they lean out the air/fuel mixture, and actually cause a loss of HP. You can rejet to compensate for the air//fuel mixture, But I have always maintained that even then you don't gain anything but getting more dirt in your engine. Any filter that flows more air has to also flow more dirt, because it is more porous. I found this article, thought someone might find it interesting.


http://forums.nicoclub.com/debunking...r-t180100.html

I am a motorcyclist, NOT a biker.


1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike
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post #2 of 17 (permalink) Old 10-11-2011, 09:05 AM
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Interesting that K&N and Amsoil didn't perform so well!

I'm keepin' all the left over parts. I'm gonna use 'em to build another bike!
_____________________________________________
"Black Beauty"
1989 VN750 acquired December, 2008, 6,711 miles
Currently 23,298 miles

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1987 VN750 project bike, acquired August, 2009, 33,000 miles and balancer sticking out of the case, currently awaiting attention and parts
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post #3 of 17 (permalink) Old 10-11-2011, 09:37 AM
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I don't get why these 'debunkers' keep wasting their time and ours. K&N does claim to have the highest filtration rate. They claim to have higher air flow rates. The other fact that 'debunkers' fail on is proving that the dirt passing through the K&N causes any engine damage. Something that real 'debunkers' (a.k.a. the paper filter manufactures who want you to buy a new one every xxx miles) have spend millions of dollars and years trying, and all failed.

After 40 years in business and 1+ million filters sold each year, shouldn't there be about 40 million ruined engines as a result of using K&N (or other such filters). Nope, none.

The choice of using K&N (or other similar filter) is higher flow rates vs higher filtration rates and environment (i.e., don't use K&N if ride through dust storms).


Chris Glennon - Portland, OR
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post #4 of 17 (permalink) Old 10-11-2011, 09:46 AM
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More or less what you would expect. Makes sense that a less restrictive filter also does a less good job in filtering the dirt.

However, I disagree about one claim in the article, namely that you cannot gain more power by increasing the air flow. Then why would turbo chargers or superchargers be installed in engines if they do not provide more power? More air + more fuel is more power. Also, a high revving engine with the same displacement as a low revving engine gives more power because more air/fuel flows through the engine.

I'm not an expert, but that just makes sense to me.
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post #5 of 17 (permalink) Old 10-11-2011, 12:44 PM Thread Starter
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Quote:
Originally Posted by pappa View Post
More or less what you would expect. Makes sense that a less restrictive filter also does a less good job in filtering the dirt.

However, I disagree about one claim in the article, namely that you cannot gain more power by increasing the air flow. Then why would turbo chargers or superchargers be installed in engines if they do not provide more power? More air + more fuel is more power. Also, a high revving engine with the same displacement as a low revving engine gives more power because more air/fuel flows through the engine.

I'm not an expert, but that just makes sense to me.
A supercharger or turbocharger pumps a whole lot more air/fuel mixture into the engine, at higher than atmospheric pressure. And while you do get more performance from that, in order to really benefit from it, your engine needs to be built from the ground up for it, with a more efficient manifold than stock, on carbed engines you need 2 high CFM carbs, you need a high lift long duration cam with a fast ramp profile, ported and polished heads, and open pipes. A higher static compression ratio is also necessary, requiring higher octane gas. You will get a lot more power out of all that, but it will mostly be somewhere near redline, and the engine will barely idle at 3000 rpm, even with the secondaries closed. In order to handle all that power, you will need to build your engine out of high quality parts, stock parts will break right away.


What I just described is a racing engine, purposely designed and built to run at full throttle. You do not want something like this on the street, it just wouldn't work. I consider K&N air filters to be racing parts, to be used on engines which are already purposely abused.

I have never seen any evidence that running a high flow air filter on an otherwise stock engine will increase power. If that were the case, running it without a filter would make even more power, but it doesn't (if anyone has any actual evidence that it does, I'd like to see it) It just wears your engine out a lot faster. It doesn't take Einstein to figure out that letting dirt into an engine is a bad thing. Where I live, dust storms are a fact of life. The best filter to use is the one that traps the most dirt, which is what an air filter is supposed to do. I do not consider an air filter to be a tuning part on a street engine. On a non racing street engine, I consider engine reliability and longevity to be far more important than a slight increase in power, so slight that you cannot tell the difference. If it takes a dyno to tell you that you have gained 2-3 hp, while cutting the life of your engine in half, is it really worth it? That of course is up to you. I will stick to stock parts on stock engines.

Oh yeah. The reason the damage caused by using K&N (or any other high flow air filter) isn't immediately obvious. It takes time for the damage to reach the point where you start to notice it, and by that time, most bikes and cars have been through several owners. Most bikes never make it to really high mileage. I have 70,000+ on my Vulcan 750, and plan on it making it to well over 100,000 miles. To most people, 50,000 miles is pretty high for a bike. I know of more that one person with over 100,000 miles on Honda Rebel 250s.

I am a motorcyclist, NOT a biker.


1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike
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post #6 of 17 (permalink) Old 10-12-2011, 09:56 AM
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Quote:
The stock filter will flow MORE THAN ENOUGH AIR to give you ALL THE HORSEPOWER the engine has to give.
I was disagreeing with this statement.

Quote:
On a non racing street engine, I consider engine reliability and longevity to be far more important than a slight increase in power, so slight that you cannot tell the difference.
I agree that you probably don't notice anything. But one should not claim that there is no improvement at all when that claim is not true.
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post #7 of 17 (permalink) Old 10-12-2011, 11:56 AM
Crap, I WAS in 5th gear.
 
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Air+Fuel

Rejetting after removing an intake restriction is required because there is more air going into the cylinder-- like you said, ohterwise it gets leaner. A larger fuel/air charge means more power. This would show up on a dyno, but I haven't been able to find anyone who compared a stock vs. shaved VN750. I'm sure it's out there, though. One piece of the puzzle that is missing here is that we don't know how effective the stock filters are- they are constructed similar to a uni filter, which doesn't filter very well at all. It just might be that the K&N filters better than our stock filter! But I doubt that.

For me, it is not worth the expense to do an ear shave for an incremental increase in power, and the aesthetics of the ears don't bother me. The VN750 is already faster 0-60 than over 99% of all automobiles; however, most people say their bike does run better after an ear shave.




Quote:
Originally Posted by VN750Rider/Jerry View Post
It has always been my contention that K&N filters not only do not increase HP, but they lean out the air/fuel mixture, and actually cause a loss of HP. You can rejet to compensate for the air//fuel mixture, But I have always maintained that even then you don't gain anything but getting more dirt in your engine. Any filter that flows more air has to also flow more dirt, because it is more porous. I found this article, thought someone might find it interesting.


http://forums.nicoclub.com/debunking...r-t180100.html
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post #8 of 17 (permalink) Old 10-12-2011, 12:05 PM
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post #9 of 17 (permalink) Old 10-12-2011, 12:17 PM
If only it had 6th gear..
 
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Quote:
Originally Posted by pappa View Post



I agree that you probably don't notice anything. But one should not claim that there is no improvement at all when that claim is not true.
All good info here but I'm putting my 2 cents in for people considering remving their airbox. I maintain that there is most definitely a difference in performance with my bike. I'll give you that it may not have any more horsepower but it get's to it's peak faster. I certainly do notice the difference and although I'm not a professional mech. by trade, I was in the past and know the difference when an engine is running and sounding better because of something I or someone else did to it even if it's minute. That's why I still try to do my own work on my vehicles when possible since I've found many shops either don't hear or feel what you're talking about when something's not right either due to lack of experience or time to diagnose properly.

If you're happy with your bikes performance, the best thing is to leave it alone (other than the mods shown to improve reliability of course), but I had a much faster and bigger cc bike before this one and the ear shave for me has made me happier to ride this little v

Dave

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Converted ACCT's to manual (thanks wib714)
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post #10 of 17 (permalink) Old 10-12-2011, 02:11 PM
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I just have to repond to Flightcontrols info on this filter test. This test DOESNOT compare apples to apples.Also the test is 2006 not the newer products on the market . Also None of these test were , certified or verified. Anyone can compare pears to apples and look good. You really think that the automobiler builders of the world use the BEST of anything in building a mass produced production automobile/truck has to read on how to purchase land in the ocean for sale..Cheap!. Just trying again to give more people the proper info not what someone wants to show them.Oh ya thanks CGLENNON for your senior input. I to am a senior. All Amsoil products are certified and verified to be true. Most other companies are also.
Thanks again for letting myself help inform our forum.
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