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I actually did this earlier this year but never posted on it. I was finding so much debris in the airbox every time I changed the air filter. I also would hear of small creatures making a home in there during winter storage.
I bought a small sifter with a handle on it for about $4 at the grocery store and removed the stainless steel mesh. I formed it around the snorkle and cut to fit leaving enough to fit a zip tie around to hold in place.






Lets plenty of air in and keeps the crap out!

Buckster,

One problem. From the looks of pics 2 and 3, it appears that the ratio of shiny steel wire to dark "air" openings looks like more than 50% blockage. It is even more detrimental when the inlet area is so small and any compromise in flow is undesirable. If you rarely or never go full throttle it won't matter that much. Fortunately, EFI's ability to dispense the mixture is not affected much, like carburetors would be, by restrictions in the air filter and further upstream where your steel mesh is. You may only have a richer full throttle mixture and less WFO performance.

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The EFI should adjust for the restriction, keeping your mixture in the correct range. Horsepower should be reduced -- and fuel economy should get better. I'd be interested in your MPG figure after the installation.

I was leary of air blockage as well, but I have noticed no noticable decrease in power although I don't peg the throttle all the way.
I don't check mileage every tank, but noticed no increase in MPG. I average 40-42 MPG mostly commuting back and forth to work. That's about 5/8 slab and 3/8 backroad.

Will it keep out Cheerios and crackers?

Yes!

I think I've seen that pic before! One of the reasons for coming up with the idea!

It certainly looks good, I do wonder about the restriction as well. FYI, the only time there would be some type of adjustment via the O2 sensor is during steady state (no sudden throttle changes) any other time the A/F map is fixed and les air in would lead to a richer mixture.

As a point of conparison the rear gate of a 5'x8' utility trailer acts as a sail above 60 mph. The air velocity is too great to "squeeze" through the diamond mesh. When trailering long distances, I remove it completely.

boxermania wrote:It certainly looks good, I do wonder about the restriction as well. FYI, the only time there would be some type of adjustment via the O2sensor is during steady state (no sudden throttle changes) any other time the A/F map is fixed.

As a point of conparison the rear gate of a 5'x8' utility trailer actes as a sail above 60 mph. The air velocity is too great to "squeeze" through the diamond mesh. When trailering long distances I removed it completely.

So your saying that, at a certain speed, the air velocity could cause the bike to starve itself of air since is no long able to "squeeze" through the holes in the mesh? (Noticed the sail-effect on my old ford ranger when I put the net on the back instead of the tailgate).

There's a complicated relationship between pressure and airflow through a mesh. As the airspeed through the mesh increases, the turbulent vortices tighten up around the individual wires of the mesh, and the airflow/pressure relationship is non-linear... But any restriction in the ariflow increases vacuun in the airbox. It's like riding around in Denver instead of at sea level.

So, it'd restrict airflow, but not be capable of fully cutting it off?
Obviously any restriction of air causes decreased engine performance, but if you're consistently facing a dirty airbox, the trade-off may be worth it.

AirForceDirt wrote:So, it'd restrict airflow, but not be capable of fully cutting it off?

Right.

Well I have noticed no difference in performance although I rarely go over 80 MPH.

The only difference is that you'd need a bit more throttle for a given speed, and you'd run out of throttle at a lower speed. If you don't wring it out at all, you'd hardly notice it. And a mouseproof airbox is a good thing.

This discussion reminds me of a gadget that some company created for cars, install this gadget and it will ensure that air flows faster into the engine via a vortex effect - see below:

http://www.vortexvalve.com/

Maybe I'll try to fit one on my bike

Just to be clear on the subject...we are talking about sub-sonic speeds at sea level? If you are, there are complications when approaching dew-point and atomization becomes a variable based on Hymler's theory of quantum compression in gaseous atmospheres.

Fill up a sink with water, pull the drain plug and what happens? a whorl pool forms because the drain pipe is round. Why wouldn't air do the same thing when traveling through the round air intake pathway?

And the NO2 emission went "up a lot" after installation of the Vortex valve (see the website and look at the Washington State emissions report).