Clamp on style air filters

[badgertom]

Has anyone tried to install the clamp on style airfilters? These filters replace the standard filter and are attached directly to the carbs (Bing Carb. on my 1982 R65. I just think they look good on a bike. But, I assume the carbs need to be re-jetted. Any advice as to what jets I'll need? Thanks.

[georgesgiralt]

Devise something to get the oil vapor the carbs normally ate from the airbox. Otherwise, you'll have a big mess in no time at all...

[Tony Smith]

Any advice as to what jets I'll need? Thanks.

Magic ones are the only ones that will work.

You see the plastic trunking actually forms part of the inlet tract so that the vapour "haze" that is emitted the wrong way out of the carbs as a result of the supersonic shock wave as a result of the valve opening is contained within the inlet tract.

Without the trunking you lose significant mixture "elasticity" due to loss of potential charge mixture and no matter what jets and needles you fit, your engine will have rev ranges where it simply cannot and will not run correctly.

By all means use trumpets or bell-mouth adapters to restore the correct inlet tract length, but you will then need to turn your mind as to where to relocate the foot pegs.

People who persist with open carb mouths or ineffective oiled paper filters clamped directly to the carbs either get used to the flat spots or get rid of them by using larger jets and different profile needles until they reach a compromise that works for them

The plastic trunking is *not* decorative

[nhmaf]

They might look like hot rod material, but as has been said, you usually lose performance, have to deal with oil mist, and they don't do nearly as good a job of keeping the dirt from getting sucked into your engine and causing wear.   Also, if you ride in a heavy rainstorm, splashes can cause them to get waterlogged and your engine can bog and stall.

On a show bike that is seldom run on the road, or a bike that is only run for short intervals on sunny days - fine, but you will be playing with jetting and needle positions to compensate.

I suppose for a sho

[nhmaf]

They might look like hot rod material, but as has been said, you usually lose performance, have to deal with oil mist, and they don't do nearly as good a job of keeping the dirt from getting sucked into your engine and causing wear.   Also, if you ride in a heavy rainstorm, splashes can cause them to get waterlogged and your engine can bog and stall.
On a show bike that is seldom run on the road, or a bike that is only run for short intervals on sunny days - fine, but you will be playing with jetting and needle positions to compensate.

[Luca]

I know this isn't an answer to your question, but aside from the almost certain loss of performance (maybe you'll do ok running WOT near redline), you've also got the ugly gap left by the airbox.  Plan on getting yourself an airbox delete cover unless you like that big ol' right angle of nothingness left behind the top cover and over the transmission.

[peteremc]

The plastic trunking is *not* decorative
 

Tony, what if the plastic trunking is retained and the pod filters were mounted where hey would normally enter the airbox? Theoretically, this would address the issue, would it not?

[peteremc]

you usually lose performance, have to deal with oil mist

This may be another of my dumb questions, but is the oil mist emitted via the breather pipe from the engine cases? I've read elsewhere on this forum that there is very little or nothing in terms of oil emitted from the breather. Any comments?

[Barry]

This may be another of my dumb questions, but is the oil mist emitted via the breather pipe from the engine cases? I've read elsewhere on this forum that there is very little or nothing in terms of oil emitted from the breather. Any comments?
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There will be more than nothing but there shouldn't be a big volume if the engine is sound and doesn't have a lot of blow by.  Maybe not fair to directly compare the stock set up with an external  breather as the intake flow and slight vacuum present in the stock set up assists extraction.

[Luca]

The oil mist will add up over time.  Keep in mind that a teaspoon of hot oil can cover a lot of territory and trap a lot of dirt.  If you made a catch bottle you could see just how much oil comes out.  I once tried to run an external breather filter and the oil condensed in the tubing I was using, causing it to stat spitting into the breather filter.  Making a catch bottle would be the way to go.

Aside from giving you a good intake tract length, the plastic elbows help support the carbs.  If you take away the airbox and then add more weight (filters) to the end of the elbows you are putting a lot of leverage on the carb mounts.

Have you considered switching to the clamshell airbox, Tom?  It doesn't have the same style as exposed filters, but a lot of folks like it better than the later flat-panel box.

[Tony Smith]

The plastic trunking is *not* decorative
 

Tony, what if the plastic trunking is retained and the pod filters were mounted where hey would normally enter the airbox? Theoretically, this would address the issue, would it not?

Yep, sure will, and you will have replaced a weather proof, effective air filtration system with a non weatherproof, less effective filtration system.


Forgive me, but I fail to see the point.

[montmil]

Forgive me, but I fail to see the point.

[smiley=tekst-toppie.gif]

[wilcom]

Point below

I just think they look good on a bike

I too have engineered around some perfectly designed systems. I like to call it "art" , not because it is art, just because once I call it "art" , you can no longer touch me, just ask the Gubermint  

[marcmax]

I take the opposite view of most of you it seems.

I have pod airfilters on my R65 and it is 100% for looks. If there is a performance penalty I don't notice it because I don't ride it hard. I know these bikes are capable of performance riding. Just look at what some of the forum members have done, very impressive. But that is not my style. I like to cruise and have no problem doing that running pod airfilters. If it takes me a few seconds longer to get to a given speed it is no big deal. I can still keep up with traffic on the highway and go fast enough to draw the attention of law enforcement if I am not careful.

I installed a catch can under the replacement starter cover and empty it every few months. To date I have never emptied more than a teaspoon of oil from it.

I also live on the coast in Florida/Georgia and have been caught in summer rainstorms that dump 2-3 inches of rain in a couple of hours. Never had a problem.

Like I said, for me it is a matter of style. I like the way it looks.

[peteremc]

OK, I'm really fishing for ideas and I am also shamelessly using all your knowledge and experience to do so. Up front, I'm putting together a fine weather, weekend ride bike for my pleasure which has (hopefully) a balance of form and function.

My main points are that I really like the way the bike rides - that's why I bought it (not my first, by the way). That doesn't have to mean that I like everything about the looks and the set up it came with from the factory.

There are probably 3 things in particular. I don't think I'm the only one who has these thoughts looking at the number of modified bikes around where owners have taken to these things and changed them. As with marcmax, these things are entirely aesthetic, but one of them has performance implications.

1. The tank. I'm sorry it's just dead plain, bordering on ugly. It looks like they couldn't be bothered to put any effort into it. There are many other BMW models around the same era as my bike (1982) that have great looking tanks. I now have one, and also have custom mounts installed on the frame so that it fits beautifully. I'm happy.

2. The battery. I'm going to do what a lot of other people have done and install it under the seat. With a little thought, this also probably could've been done initially by the factor, but I completely understand why they didn't. It will fit under the seat I have planned. I'm happy.

3. The airbox. The one that impacts on performance. I know it's a feature of the bike, but that's just what it looks like i.e. a big airbox. It's a bit like the tank. It looks like they really didn't put any thought into it - it's looks I mean, not it's performance. I totally get that it is highly efficient and works perfectly. Which is why, if I really don't like the look of it, I'm looking for options and alternatives.

No-one said that the manufacturer's product couldn't be improved upon, but sometimes there may be compromises - changing aesthetics may impact on performance, but by how much and what are the implications? What REALLY are the implications, preferably from those who have tried some changes. Balance of form and function is what I'm after.

In this thread alone, in relation to external venting of the breather, "you'll have a big mess in no time at all" became "There will be more than nothing but there shouldn't be a big volume" to an actual measurement of a teaspoon every couple of months. This is great information for me to use. Same applies to predictions about riding in the rain (which I will try to avoid on this bike). They are also highly variable, but mostly dire predictions from those who haven't done it, to a lot less dire from those who have e.g. marcmax

I've also read all sorts of dire predictions about the pod filters including misting of fuel, no mid-range power, it'll never go anywhere, the carbies will fall off from the weight and lack of support .... which is why I'm trying to find out where the ACTUAL experience sits. As expected it seems to be somewhere less dire that theory may dictate, particularly  in terms of performance. There are all sorts of comments about having to re-jet for pod filters, but Snowbum says don't bother, no need. Unfortunately, the very experienced Snowbum has so much information on his site I can't even find where I read this!! Damn.

Anyway, I'm happy that forums are for contributing ideas and I hope people will continue to help me out here. Many thanks