In search of better air filtration

[prwatts]

Hi, this may not affect most of you but out here in Saudi Arabia one dust storm can block an air filter.
I think the OEM Air Filter is lacking - it has a small frontal area and has been further blanked of with the plate with holes drilled in it (inexplicably) and has tight paper pleats - all of this must severly retrict air flow.
Then there is the 'trunk' or 'snorkel' or inlet pipe with a front that is about 2" in diameter, for a 1200cc engine suupposedly designed to rev?

I confess I cannot see the wisdom in this design so maybe someone can explain it to me, and what we can do to improve matters? Is the snout just to stop intake roar?

I bought a costly K&N Air Fil;ter and it has actual pin-prick holes that you can see through when you hold it up to the light. Apalling ! SAE Fine Test Dust goes down to 1 micron - those holes are WAY bigger. 45 pounds down the drain.

How about a washable foam filter like the MX guys use - eg Pipercross?

Many thanks
Peter

[marc]

In all of the BMW boxer air flow tests I'm aware of restricted air flow has NOT been found to be an issue. In all tests of the K&N filter on a BMW boxer that I'm aware of the K&N allowed excessive particulate matter through the filter. Dirt on the inside is not what I want for long engine life.

However... the tests I'm thinking of were with oilheads, not the filter set up used on hexheads. I still won't use K&N. It solves a non-issue on BMWs at the cost of poorer filtering. For dirty, dusty, and possible wet areas I use a UNI oiled foam filter. It filters well and can handle moisture without destroying itself. UNI also makes a pre filter that fits inside the snorkel that is favored by some who ride in dusty areas. I've never tried it myself.

[prwatts]

Originally Posted by marc

In all of the BMW boxer air flow tests I'm aware of restricted air flow has NOT been found to be an issue. In all tests of the K&N filter on a BMW boxer that I'm aware of the K&N allowed excessive particulate matter through the filter. Dirt on the inside is not what I want for long engine life.

However... the tests I'm thinking of were with oilheads, not the filter set up used on hexheads. I still won't use K&N. It solves a non-issue on BMWs at the cost of poorer filtering. For dirty, dusty, and possible wet areas I use a UNI oiled foam filter. It filters well and can handle moisture without destroying itself. UNI also makes a pre filter that fits inside the snorkel that is favored by some who ride in dusty areas. I've never tried it myself.

Thanks for this - I am new to this game and my filters seem to get dirty quickly. I live in Arabia and there is a fine powder on the inside of the filter box - fine dust is getting through. I change my oil a lot as a result, even though the GS had done 88,000kms when I got it. After 3000kms it is very dirty and not clear, sort of opaque - I hesitate to say 'muddy'
And another thing, there is a restrictive plate across the front of the OEM filter with holes drilled in it - it must cut at least 1/3 of the frontal area. Why's it there?

What do you think of Pipercross foam filters?

Peter

[marc]

Originally Posted by prwatts

And another thing, there is a restrictive plate across the front of the OEM filter with holes drilled in it - it must cut at least 1/3 of the frontal area. Why's it there?

Strength? That's just a guess. Imagine a rock that hits just right to get sucked up though the air snorkel. It would go right through the paper element. The screen limits the size of anything that can hit the paper. As for being restrictive... not unless it is the smallest opening in the air path.



I'd guess that if you measured the actual area open to air flow you'll find it is LARGER than the mouth of the air tube, meaning it doesn't add any additional restriction. I've not heard a single source that indicates a stock GS suffers from a lack of air. What makes you think that is the case?

Originally Posted by prwatts

What do you think of Pipercross foam filters?

No experience with that brand. I believe that oiled foam does better in the presence of water, and is otherwise a wash in filtering ability. I don't have any specific facts to back that believe and may well be wrong.

In your situation oiled foam might be good as you can clean and re-oil more frequently, making it cheaper than replacing filter elements. However, if the "screen" on the stock paper air filter bothers you the foam filter might just drive you crazy.



I do not notice any change in performance or power when using this filter.

[t6pilot]

are the k&n cycle filters different than their auto filters, have always felt that they were the best out their. i was going to replace the stock filter in my 2011 thinking it would offer more protection. never had any problems with their auto filters..

[prwatts]

Originally Posted by marc

Strength? That's just a guess. Imagine a rock that hits just right to get sucked up though the air snorkel. It would go right through the paper element. The screen limits the size of anything that can hit the paper. As for being restrictive... not unless it is the smallest opening in the air path.

GS FILTER PICTURE

I'd guess that if you measured the actual area open to air flow you'll find it is LARGER than the mouth of the air tube, meaning it doesn't add any additional restriction. I've not heard a single source that indicates a stock GS suffers from a lack of air. What makes you think that is the case?

OILED FOAM FILTER PICTURE

No experience with that brand. I believe that oiled foam does better in the presence of water, and is otherwise a wash in filtering ability. I don't have any specific facts to back that believe and may well be wrong.

In your situation oiled foam might be good as you can clean and re-oil more frequently, making it cheaper than replacing filter elements. However, if the "screen" on the stock paper air filter bothers you the foam filter might just drive you crazy.


I do not notice any change in performance or power when using this filter.

Wow, thanks for the pictures - I hope you never went to all the trouble of stripping your bike to take these - they are excellent and the foam filter puts it into perspective.

I must admit I never thought of rocks coming in.

I will continue my research. I would like to cut down a spare schnorkel and try that out with an Outerwear micro-mesh filter over the front. I have 2 from my quad days.

Best regards
Peter

[marc]

Originally Posted by t6pilot

are the k&n cycle filters different than their auto filters, have always felt that they were the best out their. i was going to replace the stock filter in my 2011 thinking it would offer more protection. never had any problems with their auto filters..

In general K&N flow more air. They do that by filtering less. Not a lot less, but still less... especially when freshly cleaned and oiled. Unless you need more air you are letting more stuff into your engine for no good reason.

If you don't service your own machine it's best to stick with the stock paper filters. Otherwise you'll pay for the after market filters again and again in the labor charged for cleaning and re-oiling.