My '06 gets run a lot and 90% of the time it is in the sand.
I've never had a problem with it either, but I can see that the possibilities exist if you create the right circumstances.
If the filter is dirty, there is nowhere for the dirt to stick.
and... it won't let it through. it will just let the air in and the dirt will be left in the little catcher at the bottom of the air box...
BTW: i read this in either TransWorld or RacerX in a section talking about different myths in motorcross.
Great. Now there are myths being created in TransWorld or RacerX.
Hopefully, it's a case of your misreading the mag.
Here's what really happens:
Foam filter media is made up of fairly large, open cell foam, meaning that cells, the "bubble" in the foam, are open on several sides, and are connected to each other. The media is therefore somewhat like a web membrane through which air and fluid can flow freely. The structure of the foam is such that while air can flow freely through, it cannot flow straight through. To improve air flow for performance reasons, the passageways in the foam are intentionally quite large, relative to the size of the particles it is expected to stop, and the dry foam would readily allow full sized 120 micron grains of sand to pass through without much resistance if there was enough air flow to pull it through.
To stop the dirt, the filter is saturated with oil so that each fiber of the foam matrix is thoroughly coated with it. As air winds its way through the element, making erratic 3 dimensional turns as it goes, the heavier dirt particles fail to make these turns and collide with the oil soaked foam and sticks to it.
This continues until the oil near the outside of the foam has absorbed and collected all the dirt it can, at which point, new dirt must move deeper into the element to find more viable oil to stick to. Depending on exactly how coarse the foam is, one of three things happen, both with one of the same results:
> In very coarse foam, the dirt continues to move deeper into the filter until it begins to pass completely through and into the engine, essentially unfiltered.
> In less coarse foam, or an element oiled with very aggressive filter oil capable of wetting and holding more dirt, the dirt moves deeper as in the coarser foams, but may also start to clog the outermost airways. This causes an increase in the vacuum under the filter, and draws dirt into and through the element and into the air stream.
> In even finer gauge foam, the filter may pack up and close off the air flow before th edirt has worked all the way through it, which will have a major negative effect on performance, if the bike stays running, beginning with the inability to take full throttle. Dirt will be forced through and into the intake in this case also.
The only dirt that will lay on "the little catcher" at the bottom of the air box is that which the air box caught by design. The function of an air box is to create a relatively still air zone (a plenum) from which air is drawn into the engine. This allows a chance for the heavier dirt particles to simply fall out of the inbound air, and allows the air to be drawn through the whole of the filter in a more uniform manner than would be possible with an air stream with a stronger velocity and direction that might tend to focus the dirty air at one spot on the filter.
In the case that you still don't buy any of this, check this out:http://www.thumperta...ad.php?t=565418
Leave the mythology to the Greeks and whoever wrote that article. I wonder whay other "myths" they "busted".