clip on air filters

[RSMike]

Anyone tried these (or similar)?



Would the carbs need some kind of extra support?

What would you do with the airbox and its outlets?

Would the lack of oily air be good or bad for the carbs?

Please understand its raining again here, so the mind wanders...........

[montmil]

Take a quick look at Steve Hawkins drop dead gorgeous Cafe Beemer in the current thread, Wire Wheels on a R65 can we make it work?. One picture, as they say...

With possibly more air flowing into the Bings, there could be some quality carburetor fettling time required.

Monte

[Rob Valdez 79 R65]

And if you ride in the rain, they will greatly increase the probability of getting water into your intake system.

No, the lack of oil in your carbs is not a problem, it is a blessing (IMO).
BMW just shunted the crankcase vent there for air pollution standards.
The last airhead that was vented to atmosphere from the factory was pre-1970 (/2's, etc).

Dunno about carb support.
You will probably lose some bottom-end/mid-range power, though, even with re-jetting.  Stephen can say for sure.

[nhmaf]

IMHO, they look cool, but that is their primary attribute.   They may not filter as well, which could pose longevity issues; you need to rig up a catch-can for the crankcase breather hose; you may have to do some rejetting cause they will likely cause leaner running with stock carb tuning at lower RPMs; running in the rain they will suck water into your carbs/engine; in some cases at higher speeds, you may actually end up with significantly LESS airflow because of the airflow around the cylinders and your feet/legs, combined with the fact that these filters are, just simply pointing backwards from your direction of travel (Bernouli, anyone?).  If you've got an 81-> later airbox, you've got (2) front facing snorkels which actually help to scoop/force more air into the airbox the faster you go.   This same concept is applied to many later/current model motorcycles with air-ram intakes on the front of the bike.   But, they do look cool.   If I were building a show bike, or one that I wouldn't plan to tour on and ride in dusty or wet conditions daily, I'd consider these b/c of the coolness factor.  But practically speaking, I'll not be putting these on any of my bikes.  

Just my $.02
Mike

[Barry]

(Bernouli, anyone?)

Yes I remember him. I suppose it's possible there could be a low pressure area behind the heads and in any case the air will be warm which is not a good thing for power.  I don't think the ram effect or lack of it would be very significant though.

It's a brave man that replaces the snorkel type tuned air intake system with these filters without the aid of a rolling road. I don't see how there would be any chance of retaining a  similar torque curve.

[Dizerens5]

You can get similar filters but made of a round block of some kind of foam rubber. I had pair on my old Ural twin for about 3 years. They got a bit soggy in the rain but surprisingly this had no effect on performance or starting (and I did go in a couple of rainstorms and sometimes left the bike parked outside in the rain).

[steve hawkins]

I can confirm that although I did not need to re-jet when I put mine on, they are not a performance mod as such.

In fact I would say I have lost a little at the very top end, but might have gained something lower down - but then I was running the old ali air box.

Mine are unsupported to you have to ensure that the rubbers you have connecting the carbs to the heads are new and gives a good firm grip.

I would also say that you need as much surface area as possible, mine are not connical in shape - they are oval.  I think the connical ones might be too restrictive.

This is all just hearsay as I have never been on the rolling road.  Its just a bit of fun..

[RSMike]

Thanks Steve and all, food for thought.

[Julio A.]

Those things do look really cool on a Airhead but I'd pick the original airbox with a K&N Filter anytime.

Based on my past experience replacing air filters on my dirt bike with the larger clip-ons are quite tricky since the carb jetting had to be changed since it was not running consistently through the powerband. The change can be pretty much felt like a milder effect of having an open pipe system.  

I don't know about the effect it could do to a larger engine such as the R65, but i'm not very keen on replacing jets or figuring out what to do with the large viod which used to be an airbox.

[RSMike]

Though it looks like Steve did not need to rejet, but I guess this might vary by model year ( steve said he had the older type airbox)

I just saw this rather nice (if expensive) solution to the airbox today on BMW Bayer



Though it does say "No holes for Fuellines, Electic....ideal for your own Ideas", so don't think its handling the venting which I guess needs some sort of drain/condensor/collector for oil?

more details here:
http://www.bmwbayer.de/Engine-Cover1.html

But I know what you mean Julio, there is a lot to be said for "if it ain't broke, don't fix it"

[Rob Valdez 79 R65]

I ran my crankcase breather to atmosphere long ago because I didn't like the oil dripping from the left carb onto my boot.
My eventual solution was to run it up high, terminating with a small filter.
On my last long run, I had quite a bit of oil on the left side of my bike, but I'm not sure if that was due to the breather outlet, or my leaky final drive.

Bottom line, I am going next with a catch-tank if I am fortunate enough to find a job and keep the bike.



This one is really cool!

[nhmaf]

The last photo of Rob's shows a slide type carb, which, to my limited knowledge, might be a bit less affected than the CV Bings with such a change in the air filter/supply stream.  Still, I expect that changes would still precipitate onward from there, and not always for the best.   I've not the patience/desire to pursue such tuning tweaks without my own personal "rolling road", and my wife has already spoken for most of my money these days....   a new septic system is being installed here in the coming month...