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What makes the air filter dirty?
Posted: Thu Apr 15, 2010 3:28 am
by PIStaker
Ok,
So I recently changed the air filter on my Buddy 125, and it made a huge difference in sound and performance.
So that got me thinking: What causes the air filter to dirty in the first place?
Is it safe to assume that if I am running WOT frequently, that more air is taken in, therefore it will dirty faster? Or, is it the environment that I am scooting in?
Just my random question for today.
Thanks for your help.
Posted: Thu Apr 15, 2010 3:45 am
by Lostmycage
It gets dirty because it filters air. If you've got particulates in the air that are large enough to not pass through the filter, it does it's job and the result is a dirty filter. Spring is especially hard on a filter because every plant and it's brother is trying to pollinate anything that's in the atmosphere.
It also goes without saying that the more you use it, the faster it'll get dirty; but I figured I'd throw that in there for good measure.
Posted: Thu Apr 15, 2010 3:46 am
by nissanman
The obvious answer is dirt. The same reason you need to blow your nose every once in a while... a filter can't do that, you just replace em. There is a lot of dirt close to the road and your engine likes to try and suck as much of it in as possible. If you haven't noticed just check out the road grime that builds up on a bicycle, and that's people powered!
Re: What makes the air filter dirty?
Posted: Thu Apr 15, 2010 7:41 am
by Roose Hurro
monamibuddy wrote:Ok,
So I recently changed the air filter on my Buddy 125, and it made a huge difference in sound and performance.
So that got me thinking: What causes the air filter to dirty in the first place?
Is it safe to assume that if I am running WOT frequently, that more air is taken in, therefore it will dirty faster? Or, is it the environment that I am scooting in?
Just my random question for today.
Thanks for your help.
Our planet is called "earth" for a reason...
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Posted: Thu Apr 15, 2010 7:52 am
by dawg onit
duh.com
Posted: Thu Apr 15, 2010 2:47 pm
by Vic
Is it an urban legend or do I remember reading somewhere about someone getting one of those plastic grocery bags sucked up into their scooter?
-v
Posted: Thu Apr 15, 2010 2:49 pm
by Vic
dawg onit wrote:duh.com
Not helpful. I think the OP was asking if he runs the engine harder will it cause the engine to take in more air and thus dirty the engine faster. This is not necessarily a duh question for everyone. Let's please try to keep things friendly.
-v
Re: What makes the air filter dirty?
Posted: Thu Apr 15, 2010 3:00 pm
by TVB
Roose Hurro wrote:Our planet is called "earth" for a reason...
Yes, because "Mars" was already taken, and too many people couldn't say "Uranus" without giggling.
Re: What makes the air filter dirty?
Posted: Thu Apr 15, 2010 3:04 pm
by Croatoan
monamibuddy wrote:Ok,
So that got me thinking: What causes the air filter to dirty in the first place?
Is it safe to assume that if I am running WOT frequently, that more air is taken in, therefore it will dirty faster? Or, is it the environment that I am scooting in?
Thanks for your help.
I would say it is more environment than speed. But you do need more air to go faster but how much I think is slight. Only a certain volume of air flows over the carb.
Do you ride on dirt roads? But I see you are in a city and there is a lot of particulate matter in bigger cities as well. You can check particulates on this site:
http://airnow.gov/ but it seems down right now. Sheesh Obama, you can't do anything right! ;^)
And you are San Antonio and the pollen count there right now is pretty high.
http://www.weather.com/outlook/health/a ... r/USTX1200
(That was just thinking out loud more than I think it has a real effect.)
Re: What makes the air filter dirty?
Posted: Thu Apr 15, 2010 3:39 pm
by Syd
monamibuddy wrote:Ok,
So I recently changed the air filter on my Buddy 125, and it made a huge difference in sound and performance.
So that got me thinking: What causes the air filter to dirty in the first place?
It's a dirty world.
monamibuddy wrote:Is it safe to assume that if I am running WOT frequently, that more air is taken in, therefore it will dirty faster?
I'm no scientist, but that makes sense. Let's say your buddy idles at 2000rpm and runs WOT at 8000rpm. That's four times the air through the filter and into the engine. Four times the air equals four times the dirt, in a laboratory, anyway.
monamibuddy wrote:Or, is it the environment that I am scooting in?
All other things being equal, it is speed only. But Texas is pretty dirty, so your air filter will probably clog before mine in Arizona.

Tough room
Posted: Fri Apr 16, 2010 1:15 am
by PIStaker
Wow,
Tough crowd. So I guess there is such a thing as dumb question.
Listen, I understand the concept of "it's called an air filter" Yes, I further understand that as air passes through the filter that dirt and other gunk is collected.
In my particular case the filter was very clean on the engine side and approaching black on the intake side.
As you might have gathered by now I am not what you would call a "gearhead", but when I replace the air filter in my car it is typically covered in dirt, not grease.
That said, I will revise my original question: What causes the air filter to blacken rather than dirty up as it would in my car? About 4K of my miles were put on the Scoot while living in Chicago, and now I live in San Antonio, where I've put an additional 1K miles on. Very different climates indeed.
In Chicago, I did not have the opportunity to run WOT all that often, apart from the times I was on Lakeshore Drive.
In SA, I run WOT more often than not.
I was curious to find out if the two different riding styles contributed to the sullying of the air filter in different manners. That was all.
Posted: Fri Apr 16, 2010 1:30 am
by Cheshire
Nah, not a dumb question. Newbie question, showing you're not familiar with mechanics, but not dumb. Time and experience fixes many levels of ignorance/non-familiarity. Mine's been fading quickly lately compared to when I first got my scooter.

Just ignore Statler and Waldorf.
Why blacker than your car's? I'd say a lot of it has to do with intake location and lane position. The air intake is lower to the ground and nearer the powered wheel than in a car. Also, you're riding either in or nearer the center of the lane than a car's tires, so you're kicking up more of the "grease strip" into the air...in the vicinity of the intake. It's also a smaller filter (less surface area) than a car's.
Those are my guesses at why, at least.
*edit* Got me thinking. I wonder how much of that black is brake dust? Could be another reason, though it's pure speculation on my part.
Posted: Fri Apr 16, 2010 1:35 am
by nissanman
Grease is a different story... but airfloww at different speeds is different. A car's air filter doesn't always get dirty evenly across the element, sometimes from one side to the other. At the different intake velocities the air will travel in the easiest path possible. At low RPM's that is usually different than at high RPM's. The extra dirt accumulated on one side of the filter at WOT is most likely indicating the preffered path under those conditions. I hope this makes some sense. This is why there are so many products aimed at improving airflow into the intake of a vehicle to improve performance. Most often an older V-8 in the form of intakes, throttle body spacers, carb spacers etc to get a different effect on the air/fuel mixture as it enters the cylinder.
Posted: Fri Apr 16, 2010 1:38 am
by lmyers
Air filter, schmair filter... are you attending Amerivespa since it's in your town?
Re: Tough room
Posted: Fri Apr 16, 2010 6:30 am
by Syd
monamibuddy wrote:Wow,Tough crowd.
I hope you weren't taking me too seriously. I rarely do.
monamibuddy wrote:In my particular case the filter was very clean on the engine side and approaching black on the intake side.
Maybe it's tire and asphalt dust that the car's air cleaner misses due to its location.