K&N air filter VS OEM

First off I have a 2001 VFR. Bone stock.
I know this has been discussed in other threads but I want to add something to the "which filter to buy" question. I decided to replace my airfilter as I had no clue if the previous owner had done it. I purchased the K&N air filter because it was actually a little cheaper than the OEM. However I was not too happy to see the surface area of the K&N was smaller than the OEM. Searching through the previous posts on this subject I saw that others had questioned this apparent problem.
I wondered why the K&N seemed smaller. As others had stated I too did not want to have reduced flow because of the smaller filter area. So I took a closer look at the oem. If you look at the bottom, or carb side of the filter you will notice the paper element is supported by a screen. This screen is sheet metal and perforated by numerous holes. If you examine the screen closely you will notice that there is a fair amount of metal between each hole. I had some time to kill so I investigated a bit more.
The oem filter is about 24 cm x 17.5 cm giving a surface area of 420 sq cm, or 65 sq inches. However this area is greatly reduced by the sheet metal mesh screen, in spite of the perforations. I counted approximately 476 holes(17 one way 28 the other then multiply). The holes measure about 8mm in diameter. Using the formula PIxR2=area of a circle, I determined the perforations add up to about 239sq cm or 37 sq in.
So of the total potential area of the oem is 65 sq in you really get 37 sq in.
The K&N filter area measures about 6.75 by 7 in or 47 sq in.
So in fact the filter surface area of the K&N is 10 sq in larger than oem.
I had not heard of the BMC filter until I searched the posts on this site so I did not have an opportunity to purchase one.
I have seen the BMC filter on their website, and it seems to offer even more surface area than the K&N.
So bottom line to me is both the K&N and BMC offer potentially greater flow capability than OEM.
Since I have already purchased the K&N I will stay with that , but the BMC may be the better route.
I do not know wether the K&N or BMC offer any real performance gain. I assume the FI compensates for the increased flow to some degree. If I had access to a dyno, it would be interesting to compare the three filters.
BTW the original air filter on my bike looked absolutely plugged with dirt and debris, so I am sure I will notice a difference in the way the bike runs.

 

if its on the internet it must be true : )

 

My kind of thinking mailmanbob! Great info.

I am taking a look at what my bike has this weekend. with 5700 miles I am assuming OEM but would be nice to find a K&N or BMC filter inside.

K&N filters can potentially become severely clogged as well if you neglect to "recharge" due to the fact it is an oil/cotton element filter instead of a dry paper element filter.

Although not likely, If you ride in dusty conditions the filter could prematurely get gunked up with dust that turns to "mud" once it hits the oil in the filter. Although not on a bike, i experienced this first hand with my S10 which I had a K&N cone filter at the end of a cold air intake. basically the filter was exposed to the elements much more than the stock filter. But, by the end of just 15,000 on the road miles and a probably 50 miles combined on dirt/gravel roads my filter was very dark gray, almost black in color. I used a K&N cleaning "recharge" kit on the filter and it looked brand new by the time it was ready to be reinstalled. I could once again hear the air "wooshhhh" sound entering the intake again which was actually muffled by all the muck that was clinging to the filter. In hindsight the filter really did a wonderful job stopping all the crud entering the engine. Also on the inside of the filter it still was the K&N red so the filters really do a great job.

Granted most of us keep a close eye on the vitals of our machines it just something to pay a little bit of extra attention too especially if we have a very dry summer or you have a mile long dirt/gravel road.

 

Did you know that 80% of all statistics are made up on the spot?

 

I've allways run K&N Filters, can't say I noticed any real improvement over oem, but they save money since they're reusable. I think the airbox or snorkle limits airflow on most bikes but they are jetted to compensate... so if airbox is modded jetting will need to be redone, then a real gain maybe possible. I've only done this on XR600/XR650R dirt bikes with rejetting, much louder intake and improved power.

 

A dirty air filter of any make or construction is just that. The major point here is that the K&N's are cleanable and re-usable. I'm running K&N's on three bikes. One has a can type that has been on the bike since 1980. Two on another since about 88-89 and from the getgo on the 91 VFR about a week after I bought it. No problems ever.

 

Just get an OEM one, what do you think you get from K&N about 0.001 horsepower? If you dont spend $300 on a Power Commander and another $300 or more on a dyno tune and another $200 of a fuel pressure regulator then your lonely K&N wont do jack. Further more somewhere on this board is a link to a particle test that K&N allows 1800% more dirt through than the OEM. You know what is great about K&N,,,their marketing department!

 

It's not totally empirical I know...but I've removed the air filters on MANY motorcycles and ATVs of all types. Based on the amount of material and wear I've seen on throttle slides and throttle bodies, I tend to think the OEM elements filter better. If that stuff is getting through to that point...you know it's making it's way to the rings too. So if longevity is a concern....

 

The K&N may allow 1800% more dirt to pass but at least its clean dirt.

 

Nothing like clean dirt I always say..

Probably 50K on the K&N on my 91. No offroading on the VFR at least on purpose. Radials are not really great on gravel. The K&N's are easy to clean. I prop the tank with a chunk of 2X4 takes maybe ten minutes to do tops.

 

Some interesting reading here: K&N air filter or OEM, why OEM is better

 

Its nice to have that test data but common sense should be use first. K&N is about equal to Slick 50. When Slick 50 first came out it was thought to be the best thing that ever happened to an engine until all that PTFE started clogging up oil filters and oil passages and engines started to seize. IMHO I think a K&N filter will cause a slow death to your engine. My buddy ran his 98 VFR for 6 years with a K&N and when he did his valve adjustment all his cam lobes were pitted and scored. I cant say it was 100% the fault of the filter but when I did mine with more than double the mileage my cams looked like new. As a test I put a K&N in my bike and really noticed no performance increase from 1st to 3rd gear. I think kids see race cars and race bikes and say "Wow he's running a K&N filter, I should too!" but these guys have unlimited resources and money to rebuild theie engines after every race and if an engine blows then so they have 4 others ready to go. I like the engine I have and I have no desire to replace it.....unless its one with a TOROCharger!

 

Did your buddy clean his K&N or just let it go for six years? I am trying to establish the relationship of a dirty air filiter and pitted cam lobes. Maybe he was running Slick 50?

 

Air filter won't cause cam wear, oiling syslem issue or lack of correct valve lash or cam defect.

 

I can only assumed he cleaned it but the how and when is anybodies guess. I helped him with his valve adjustment and was a little taken back buy what I saw. I am no engine expert but I think the K&N was partially to blame esp if it was neglected or just not doing what its supposed to do. At least his bike still runs pretty well. No he wasnt running Slick 50, god is that even still around anymore?

 

I ran screened velocity stacks in the 70s on built Honda Fours with no issues, even in the rain.

 

Type of oil and filters, frequency of changes, etc would be the place to look I would think...