Playing with UNI filters

[cele0001]

I have posted this thread on R1150.net but I am hoping for more feedback here. It is related to the GS since I think it is the same setup for all oilheads.

Since I am doing some experimentation that will require me to take the transmission out (again ) pretty soon (maybe more than once) I wanted to simplify the dis-assembly. One obvious PITA is the air box which is in the way of everything. I took it off during the last transmission R&R and installed 15 degree UNI filters (2 1/4'' I believe). They have extra sleeve on them (red).
After installing them I was not really happy since they are touching the fuel lines and there is intake noise , sound pulses during intake, especially at low rpm high load (acceleration). Here is a picture.

So on to the phase two. If you remove the intake tubes from the air box you can see that they are actually made of two pieces that are locked into each other. Sorry no picture I was too fast. Using a drill to drill down the nipple you can separate them.
Here is a piece that stays (not used).
EDIT: The box under the part is unrelated to the mod.

Then you use the part of the intake and install the UNI filter (nice tight fit). The final product looks like this.

No more low end noise and even nicer sound during acceleration. Additionally air filters are more in the bike and therefore protected from the elements.
Total cost $38 (for the filters). No issues with the fuel mixture (that I can notice) . Bike runs great. As you can see I am also on the shorty pipe.
The whole thing is reversible since you can just add a dab of glue to put intake runners back together if I decide to go back. They are almost "interference fit" anyway.


Open for comments.

 

[GARAGE HERMIT X2]

look's ok to me, what are you experimenting with the g/box,

 

[cele0001]

The famous input shaft splines.

 

[Timolgra]

"Since I am doing some experimentation that will require me to take the transmission out (again ) pretty soon (maybe more than once) I wanted to simplify the dis-assembly."

That's possibly the only real advantage apart from freeing up some storage space under the seat but haven't you restricted the the surface area of the filter significantly which will have an effect at high revs and I would argue it's now more exposed to the elements rather than less.

Performance is possibly ok with your 'phase one' set up but can understand your concern at the amount of induction noise, I have the same issue using a Rally air filter set up on a KTM 690 which dispenses with the intake snorkel, it's just too loud for long rides.

 

[Steptoe]

You're reducing the torque of your engine. Or moving it so far up the rev range that it's pointless on an old basic BMW flat twin.

 

[cele0001]

If you are referring the the extra sleeve as a restriction I don't think it is doing much since I am running it dry and the foam is not very thick. If you are referring to the fact that the filters are inside the bike again IMO there is plenty of air around to not make a difference.
Steptoe on your comment, could you explain the relationship of intake runner to torque at rpms?
Granted we are dealing with a lot of science so if you have a link to an article it would be appreciated.
My understanding is that longer runner is good at low rpms and they should be shorter as the revs pick up. I think I was reading somewhere about somebody (facts only ) running variable runners (a tube inside a tube controlled by a motor). Automotive has been doing it for a while with a flap (but only two lengths)
In my case I am running about 75% of the original runner.
I will concede that there is probably some loss of torque down low and last night while i was on my midnight run I would hear the pulses up until about 2000 rpm but beyond that it is imperceptible (to me anyway).
In either case I appreciate the comments and not the mandatory "leave it alone, Germans know what they are doing"
Esmir

 

[Timolgra]

If you are referring the the extra sleeve as a restriction I don't think it is doing much since I am running it dry and the foam is not very thick.

I hope there's no dust where you ride.

 

[GARAGE HERMIT X2]

i think the length of the intake tract on a street bike is immaterial, different if your racing, even then the set length of it will only come into play at a certain rev figure,

 

[cele0001]

I hope there's no dust where you ride.

The filter under the sleeve is oiled and that is the part that does the filtering. According to manufacturer's recommendation if riding in really wet or dusty conditions you should oil the outside sleeve also. Most of my dirt racing friends use UNI filters and its the "bees knees" or "dogs bollocks" (just wanted to use that in a sentence). Of course those are 2 stroke so completely different animal. I have no illusions about power gains but I see no reason to believe it is worse than factory regarding filtering. According to my reading "wet" filters are comparable to dry regarding particle filtration.
First rule is always "do no harm" so that is where I come from.

 

[Timolgra]

The filter under the sleeve is oiled and that is the part that does the filtering. According to manufacturer's recommendation if riding in really wet or dusty conditions you should oil the outside sleeve also. Most of my dirt racing friends use UNI filters and its the "bees knees" or "dogs bollocks" (just wanted to use that in a sentence). Of course those are 2 stroke so completely different animal. I have no illusions about power gains but I see no reason to believe it is worse than factory regarding filtering. According to my reading "wet" filters are comparable to dry regarding particle filtration.
First rule is always "do no harm" so that is where I come from.

Yes, I agree about Uni filters, that's what I use in some bikes but are you comparing wet filter to paper for particle filtration? I think it's well accepted that a quality wet filter is much better .....anyway, we're off topic now

 

[kennyc]

i think the length of the intake tract on a street bike is immaterial, different if your racing, even then the set length of it will only come into play at a certain rev figure,

http://www.ibmwr.org/r-tech/oilheads/R11pwmod.shtml as you are talking about GS's then probably no biggie, but for the RT riders, an improvement in useable torque at a very low cost, and probably a lot lower cost than after market filters, of course they are invisible to the naked eye and so are not going to be worth as much to a serious customiser in search of extra performance, (BTW Red is usually the fastest )

 

[cele0001]

Although I agree with you on red being the fastest in this case the cover came with the filter and it was red (no option). I might take it off but I don't want to have oily filter directly exposed. It gets messy if you have to touch it.

 

[(RIP) Kaister]

Steptoe on your comment, could you explain the relationship of intake runner to torque at rpms?
Granted we are dealing with a lot of science so if you have a link to an article it would be appreciated.
My understanding is that longer runner is good at low rpms and they should be shorter as the revs pick up. I think I was reading somewhere about somebody (facts only ) running variable runners (a tube inside a tube controlled by a motor). Automotive has been doing it for a while with a flap (but only two lengths)
In my case I am running about 75% of the original runner.
I will concede that there is probably some loss of torque down low and last night while i was on my midnight run I would hear the pulses up until about 2000 rpm but beyond that it is imperceptible (to me anyway).
In either case I appreciate the comments and not the mandatory "leave it alone, Germans know what they are doing"
Esmir

Part 1 (http://autospeed.drive.com.au/cms/A_1361/article.html),
Part 2 (http://autospeed.drive.com.au/cms/A_1370/article.html),
Part 3 (http://autospeed.drive.com.au/cms/A_1379/article.html).

 

[cele0001]

It shows website is down, but will check it out. Thanks

 

[(RIP) Kaister]

try here :

http://www.autospeed.com/cms/article.html?A=1361
http://www.autospeed.com/cms/article.html?&A=1370
http://www.autospeed.com/cms/article.html?&A=1379

and

http://www.autospeed.com/cms/article.html?&A=111486

 

[cele0001]

Thanks, good info but a little "generic" and most of the stuff is common sense.

 

[cele0001]

Bump.

 

[GARAGE HERMIT X2]

why have you "bumped" your thread,

 

[sykospain]

Hi,
Esmir bumped his thread on UNI filters 'cos he was forwardng it to me as I'm interested in the idea of getting rid of the OEM airbox on my Rockster.

It's bad enough having to go through the toil even of just removing the tank, before ever getting to the 2-hour job of splitting the tranny. And it seems the biggest PITA throughout the job is levering the top thick wires that loop over the l/h battery box spigot. And refitting that darned airbox again is a real pain.

I'm fully aware that Steptoe, a real expert in these 6-speed bikes, disapproves of switching air filtering systems, but the fact is that the hydraulic clutch models simply have to be torn apart every 20K miles for lubing or fitment of Esmir's brilliant Spacer idea. Mind you, what other motor manufacturer admits that as part of a 'regular' service routine, the sodding tranny has to be split ?
But that's BMW for you - since the Car Division took over Spandau and started slashing at quality and service..
As the new slimline Mr. Harris says succinctly in his fascinating U-Toob contributions, "BMW = Bikes Made Weird".

A final thought: R1200RT "Suspension Control" variant purchasers in BMW's biggest market, the USA, all just received $1,500 in compensation from BMW America for having to return their brand new $20,000 bikes when Berlin discovered that due to their cheapo out-sourcing from Spandau to Slovakia or somewhere, of a crucial component involved in operating the "electric suspension control" - what a mad idea anyway - might cause the rear wheel to lock up, sending a message to all owners of this variant on the lines of "On no account should you ride your bike" ! !
Whereas...
In the UK, such purchasers of the bike that only came to market four months ago, are offered a £500 voucher to spend on BMW stuff which they probably alreadyhave anyway.
That's how much BMW Bracknell thinks of "Customer Relations".
Regards,
ALAN in s.e. Spain

 

[cele0001]

In retrospect I should have sent the link. I was lazy and it was easier. Apologies