K&N filters are...

[chasbmw]

at least if you are in Aussi, its easy to see how much red dust is getting through your filters,

[ME 109]

I think the real question is, how small a particle do you need to filter? Do the minute particles that get through an oiled K&N or even a paper filter really do anything to your motor?

Perhaps more than size, is the type of particle itself.
Silica (sand) ain't good, where other similarly sized particles like organic shite, may not be as bad.
I try and go faster than the dust anyhowz.

[mattcfish]

Here's a good article by somebody who actually tested the difference between filters.
http://www.bobistheoilguy.com/airfilter/airtest1.htm
Stock paper filters seem to win on filtration, but not by much, they all let dirt through.

[Unclviny]

http://home.roadrunner.com/~jbplock/ISO5011/SPICER.htm

Vince

[Motorhead]

K&N filters are junk

the ole filter system on /5 with paper has proven realiable working an over engineered

[rinkydink]

They ARE better than open-stacks as far as screening out small Children and Dogs!

On my Norton Commando I am running screened-Stacks with oiled-Microphone-Windsocks (Shure SM-58) on them as I think the filtering properties are at least as good as K&N's (plus they look better, are available in colors and are WAY!! cheaper).

Vince

Great for filtering but how good is your high frequency roll off?

[Major Softie]

Nice to see another audio geek on the site.

[Motorhead]

I think the real question is, how small a particle do you need to filter? Do the minute particles that get through an oiled K&N or even a paper filter really do anything to your motor?

some particals do get through...

so a good filter maybe lets a polish particle....

and a poor filter let in 80# grit...

[mattcfish]

I think the real question is, how small a particle do you need to filter? Do the minute particles that get through an oiled K&N or even a paper filter really do anything to your motor?

some particals do get through...

so a good filter maybe lets a polish particle....

and a poor filter let in 80# grit...

All I can say is I ran K&N's on my bike for over 20 years without a problem. I sold the iron lined barrels, pistons, and rings about a year and a half ago. I did not sell them because they were worn out (I had put over 50,000 miles on them). They were in excellent condition, the bike did not burn oil, and the compression was over 150 Lbs each cylinder. OK, I had re-ringed about 30,000 ago. The reason I sold them is because I wanted to upgrade to 1000cc and Nikasil.
I run a K&N on my 71 VW van which I've owned longer than the Cycle. After nearly 80,000 on the rebuilt motor she still doesn't burn oil (leaks yes ). My 75 BMW 2002 also has a K&N (no issues, lotsa miles). Many engines with stock filters don't make it this far. The minute particles that are getting through don't seem to be making a difference and we've got lots of volcanic dust here (the 3 months of the year when it's not raining).
Do most other filters filter better? it looks like a resounding yes. I'm just not convinced it matters.
Just my personal observation.

[rinkydink]

Yes, it does matter, but me thinks since you're a gearhead like the rest of us.....oil changes were done religiously and you cleaned the K&N more often than not. That pretty much takes care of the air filter debate, unless, of course you use an SM58 pop filter (windsock) instead...YMMV