Removing the Pulse Air Injection System

[pedrocasper]

I have a 1984 R100, in which I'd like to remove the Pulse Air Injection System (PAIS) and traditional airbox. I found the following article on internet riders.

http://www.ibmwr.org/r-tech/airheads/plug_fresh_air.shtml

I'd like to put K&N round/bullet type airfilters on the bike for a more traditional cafe look. My concern is the breather hoses and fittings. I like to run the breather hose into a nice catch can I will mount on the bike. I have done this on smaller displacement honda CBs that I race, but was wondering if anyone has done this on an airhead. I will still be using this bike as my street bike, so I don't want to really screw things up for pure asthetics and limited power gain.

[bikerfish1100]

i picked up a small K&N filter unit for exiting the oil breather hose into. Sorry, no pics.

[jdmetzger]

You could simply remove the pule air system. You just need two plugs and some red loctite for where the tubes go into the heads (some dealers sell these) and then pull the rest of that useless system off. You'll also need rubber plugs for where the tubes go into the airbox... although you want to remove that box, so I guess you won't, after all.

I'd look to use something different than a K&N. I used to run them in my trucks, until many tests have shown how much extra dirt they let into your engine. I wonder if there is a paper filter you could use in place of the K&N so you have the look AND functionality?

[pedrocasper]

You could simply remove the pule air system. You just need two plugs and some red loctite for where the tubes go into the heads (some dealers sell these) and then pull the rest of that useless system off. You'll also need rubber plugs for where the tubes go into the airbox... although you want to remove that box, so I guess you won't, after all.

I'd look to use something different than a K&N. I used to run them in my trucks, until many tests have shown how much extra dirt they let into your engine. I wonder if there is a paper filter you could use in place of the K&N so you have the look AND functionality?

That is a good suggestion. I know there are aftermarket filter screens that you can slip over K&N filters, but I don't know how much additional protection that offers from dirt/dust. I run straight velocity stacks on my honda cb350 roadracer, but I am not worried about dirt on that bike since I only run it 8 miles at a time.

The filter on the breather hose is also a good idea. I have a bunch laying around that I think will fit.

[pmdave]

The flat BMW filter is pretty good, and the square airbox fits over the transmission nicely, providing a place to catch the breather blowby oil. The only change I would suggest to that system is if you have a cast aluminum filter top. The later (plastic) version is lighter, smoother, and provides good intake vacuum for those Bing carbs to function correctly.

Timing plugs will snap right into the holes in the aluminum filter base once you remove the air tubes.

pmdave

[Ray1505]

Re-Psycle sells a kit to get rid of recurculation gases system. Not very expensive and it works. Bike runs good too!
I even took the front solenoid out from under the engine top cover.

[Jeff488]

I used oilhead oil drain plugs/washers with a good dose of anti-seize compound to plug my heads.

[ducatipaso]

yup i did it

[lbrackr756]

I have a 1984 R100, in which I'd like to remove the Pulse Air Injection System (PAIS) and traditional airbox. I found the following article on internet riders.

http://www.ibmwr.org/r-tech/airheads/plug_fresh_air.shtml

I'd like to put K&N round/bullet type airfilters on the bike for a more traditional cafe look. My concern is the breather hoses and fittings. I like to run the breather hose into a nice catch can I will mount on the bike. I have done this on smaller displacement honda CBs that I race, but was wondering if anyone has done this on an airhead. I will still be using this bike as my street bike, so I don't want to really screw things up for pure asthetics and limited power gain.

I just used a 5/16" ball bearing inserted where the tubes come out of the airbox. Took 5 minutes and the bike still looks bone stock.:thumb

[Stuff2C]

remove the tubes from the heads, remove the tubes from the nuts (takes a little work) braze them closed and reinsert.

[JohnP]

After a measly 17k miles on my 84 R100 with the air injection system on, and the serious admonitions at the Vermont rally to get rid of it, I pulled my system when I returned (but saved it). Debated whether to plug the lines with ball bearings to preserve stock look or to yank them and decided to yank them for a cleaner look. Fortunately the head connections came out easily. Bob's BMW sells a kit with threaded hex plugs for the heads and rubber plugs for the airbox. Decided to keep my airbox stock. Biggest time was pulling up the stock airbox to paint it and also replaced the crossover fuel line (original and leaking) underneath the airbox while I was at it.

[lkchris]

Since K&N filters don't filter anything, be sure and post your VIN number so we can all avoid your bike when you decide to sell it.

[pedrocasper]

Since K&N filters don't filter anything, be sure and post your VIN number so we can all avoid your bike when you decide to sell it.

You know, suggested alternatives are always welcomed along with wise cracks.

[keelerb]

I have always considered K&N filters to be the best. What am I missing here? (Please resist the urge to respond, "Large chunks of dirt....") Thanks - BrianK

[bikerfish1100]

I have always considered K&N filters to be the best. What am I missing here? (Please resist the urge to respond, "Large chunks of dirt....") Thanks - BrianK

lots of noise from some car & truck testing of K&N air filters, along with other brands.
K&Ns don't filter especially well until after they have built up some layer of collected yuck.

[sumran]

I have heard from several experienced mechanics that the K & N filters allow a substantial amount of fine particles to get into the engine. I have also been told by many that I respect that the stock BMW filter is hard to improve on, especially the flat filter that came on later airheads. That is what I have on mine. When I change it there is dirt on top of the filter and none in the carbs or the airbox below the filter. I have also been told that cleaning and reusing the stock filter will cause premature wear.

The don't cost that much and they don't have to be changed that often, so I stick with the stock ones.

[widebmw]

You know, suggested alternatives are always welcomed along with wise cracks.

A good alternative is the UNI filter, oiled foam.
http://www.unifilter.com/online%20catalog/streetbmw.html

[20774]

I have always considered K&N filters to be the best. What am I missing here?

One person's opinion is here http://bmwmotorcycletech.info/K%20&%20N.htm and seems to be shared by many on the Airheads tech list.

[brickrider]

lkchris: Since K&N filters don't filter anything, be sure and post your VIN number so we can all avoid your bike when you decide to sell it

"The Sting of Criticism, is the Truth in it." -- Benjamin Franklin

[The_Veg]

...the stock BMW filter is hard to improve on, especially the flat filter that came on later airheads. That is what I have on mine... They don't cost that much and they don't have to be changed that often, so I stick with the stock ones.

The late-model airhead filter is of similar construction to the filter my car takes, but is half the size and three times the price. :banghead

[Jeff488]

The late-model airhead filter is of similar construction to the filter my car takes, but is half the size and three times the price. :banghead

No doubt. However, BMW probably doesn't sell a million of these a year, so production costs aren't spread over so many units. But I reckon you already know that.
Besides, it's a genuine BMW part, having been lovingly crafted by elves(who punch in on a cuckoo clock) in the Schvarzevald!(Here's where the music fades in: "Duetchland uber alles"):german

[yllib]

I have often found that removing the stock velocity stacks that come in the square airbox kills midrange.

I have found that having two large air horns instead of one large and one small kills midrange.

I run my crank vent to the ground but be careful how you do it because the slip stream can pull it back up and on your rear tire and stuff.

Square air boxes should not be a crank vent sump. It makes a mess.

Oilhead sump drain plugs are excellent plugs for the air pump port on the heads.

I have serviced hundreds AND hundreds of late model square airbox beemers and I think that K+N filters filter dirt and dust WAY better than the stock filters. I have taken SO many stock filters out and that airbox looks like a litter box! I have seen photos of people testing clean and almost oil free K+N's and they wonder why they didn't filter well. READ THE INSTRUCTIONS. Don't clean them and keep them OILED. Guess what? Dry Uni filters don't filter either. I have seen that a lot as well. The internet K+N doesn't filter crap is crap! Go to the races. See what they are running. If you think every XR and DL out there is running K+N's because they don't filter you are an idiot. XR's anyway have plenty of room for about ANY type filter and those guys are spending hundreds of thousands of dollars trying to win a National Championship.

Square K+N's need to be modified or they don't fit right and suck dirt. The front will bow back.

I know a lot of experienced mechanics that don't know what they are talking about. Try to find one that does.

[20774]

...and those guys are spending hundreds of thousands of dollars trying to win a National Championship.

But how many of them are trying to get hundreds of thousands of miles out of the same engine block/top end? Much of those thousands of dollars goes into rebuilds of the engine in order to win that championship.

And something just seems logically wrong with those filters... Keep the filter/foam dirty/oil/etc. so that it filters better?? And how do you control the level of dirty/oil/etc. so you get consistent filtering?? What's wrong with that picture? :scratch

[yllib]

There is SO much money in professional flat tracking that the tuners wear their bikes out on purpose so they can rebuild them as often as they can? Get real!

I am familiar with a lot of runner up and one Grand National Championship effort. A lot of those races are won by inches. When those guys get an engine together that for SOME reason is a runner, the last thing they want to do is take it back apart!

Logic??!!?? There is no better way to get to the wrong conclusion with confidence.

[20774]

OK, my reality take is this...I suspect it would apply to a vast number of people who hang around here. BMW designed the intake and filtration system and exhaust to get the best all around performance, from idle up to redline. Most people never make it to redline or spend any kind of time there. They're not racing on the streets, so inches of performance are not important. Those racers you mention are spending 95% of their time at or near redline. I'll agree they need some airflow. But no one really needs that for the street, not on a consistent basis.

I think if you're going to tweak your bike, there are other areas that can benefit a lot by small changes. People have already stated that some changes might affect various ranges of performance. It's not all straightforward...just open up the intake and she'll run better? Hardly...everything has to work together. Most just want a reliable ride with a decent amount of longevity.

IMHO, I'd never do something like this which has the possibility of ruin the performance and requiring further dipping into my bank account all the while possibly subjecting the engine to detrimental debris, etc.

But there's always a small fraction of the larger group who want to go down that path. I'm just not one of them.

[pedrocasper]

"The Sting of Criticism, is the Truth in it." -- Benjamin Franklin

"All of civility depends on being able to contain the rage [and rants] of individuals."
-- Joshua Lederberg

I didn't think the question would raise such interesting and educational dialogue. I think I will just plug the PAIS, retain the stock air-box and move on. I have not heard that removing the airbox improves overall performance much, infact could dimish it in the midrange.

Maybe setting up a forced air system like the v-max engine is the way to go!? (Just kidding)!!!

[lkchris]

" I have not heard that removing the airbox improves overall performance much, infact could dimish it in the midrange.


BMW's middle name ain't motor for nothing!

[sumran]

The late-model airhead filter is of similar construction to the filter my car takes, but is half the size and three times the price. :banghead

:laugh Can't argue with your logic. However, compared to all the other money spent on parts, accessories, gear...

When I first started, I thought buying the motorcycle was the big expense. If it was just boring transportation, I'm sure I would spend much less. I never catch myself daydreaming about taking my truck out for a spin.

[yllib]

OK, my reality take is this...I suspect it would apply to a vast number of people who hang around here. BMW designed the intake and filtration system and exhaust to get the best all around performance, from idle up to redline. Most people never make it to redline or spend any kind of time there. They're not racing on the streets, so inches of performance are not important. Those racers you mention are spending 95% of their time at or near redline. I'll agree they need some airflow. But no one really needs that for the street, not on a consistent basis.

I think if you're going to tweak your bike, there are other areas that can benefit a lot by small changes. People have already stated that some changes might affect various ranges of performance. It's not all straightforward...just open up the intake and she'll run better? Hardly...everything has to work together. Most just want a reliable ride with a decent amount of longevity.

IMHO, I'd never do something like this which has the possibility of ruin the performance and requiring further dipping into my bank account all the while possibly subjecting the engine to detrimental debris, etc.

But there's always a small fraction of the larger group who want to go down that path. I'm just not one of them.

I use K+N filters on my own bikes because they filter much better that the stock paper ones. IF you modify them so they fit right and follow their instructions, I never even see a fine layer of dust inside my square airboxes and that includes multi-bike offroad rides with a LOT of dust. Can't even come close to saying the same thing with stock paper filters on the SAME bikes. I don't use them for performance. I don't think they make any difference. I have installed them on a lot of bikes and they never needed re-jetting. I use them because they filter better.

[spencer]

can someone explain how to modify k+n filters for proper fit on post-1980 airboxes?

[yllib]

Put your new K+N filter on the bike and mark it with a magic marker where it meets the starter cover. Take it back off and cut two indentations into the filter so that the starter cover will slide into the filter. I make the indentation from the bottom of the filter to just a bit into the curve of the starter cover where it flattens out and becomes the top of the cover and cut the grooves into the filter about an eight of an inch deep and a bit wider. Now when you install the filter it should slide over the rear side edges of the starter cover. This allows the filter's front lower lip to go OVER the front edge of the airbox like it is suppose to. I stick a tiny light into the cutout in the starter cover for the air pump vacuum line and look in between the starter cover and the air box to make sure the filter's lip is completely over the edge. NOW the filter can filter!

I say new filter because once the filter has been bowed back for some time the rubber filter body get a memory and it won't stay in the correct position.

Be careful. Exacto blades are dangerous!

[BubbaZanetti]

i know where you're trying to go with this..........

read: "traditional" BMW "cafe" setup is removing the airbox and putting on two little pod filters.

most of the people criticizing this idea are from the "function over form" mindset (NO offense guys!!)


i love cafe racers and am thinking about building one myself this spring. my last airhead had drop bars, bar ends and a slightly modified rear end, nothing too crazy. i'm of totally mixed feelings over the way the airbox removal thing looks. on one had it does follow the cafe ethos of "minimalism" but on the other hand, it looks like someone kicked a big chunk out of the engine, since (and esp on the aluminum airbox model) the airbox follows the lines of the engine.

i would say marginal gains in "looks" (again opinion) and weight (who cares) wouldn't out weigh the change in performance.

btw, one cool thing you can do to your 84, which i did to mine, is remove the license plate bracket and install the plate vertically, very "cafe", very "slimming", cleans up the rear end. if chopper dudes can attach plates vertically to the transmission case, anyone should be able to, hahah

http://bubbazanetti.smugmug.com/photos/143409251-M.jpg

[pedrocasper]

Yeah, I understand your desire re: cafe bikes. I posted pictures of my R100 in the airhead post a picture thread, so not to do it again, here is the link:
http://www.bmwmoa.org/forum/showthread.php?t=2140&page=48

As you will notice, I have an aftermarket cowling (solo seat) and a license plate holder slim and modified. If you are interested in cafe bikes, check out the other forum I blog on. Lots of cafe vintage roadracer folks on that forum. I'd like to see more pics of your bike!

www.caferacer.net.

[The_Veg]

Also check out rockerboxer.com (http://www.rockerboxer.com)

[pedrocasper]

Also check out rockerboxer.com (http://www.rockerboxer.com)

Yeah, I proudly wear the T-shirt he sells! That is a great site. Full of inspiration.

[The_Veg]

The guy behind RockerBoxer is that Vanzen fellow who has posted here about his Old Cro project. I met him recently after knowing him via forum-posts for years. Great guy to hang out with and talk bikes.

[wpunch]

I have a '83 R100 with almost 49,000 miles, and I have been putting up with the damn oil leak on the back side of the carbs since the bike was new! Why?? I don't know!
I am REALLY ready for a fix that works.

There are a couple of different ways described here, to solve the problem.
My question is, does this really work? Is there any more oil seepage/leaks?

My 2nd question ...
I just noticed the left side metal/rubber tube that runs from the jug to the engine block is corroded, just like the other side did a few years ago. I don't care to spend the bucks to replace it.
With the above fix, do I just leave the tube there?

Many thanks!

[pedrocasper]

The guy behind RockerBoxer is that Vanzen fellow who has posted here about his Old Cro project. I met him recently after knowing him via forum-posts for years. Great guy to hang out with and talk bikes.

Hey, why is the GS named "El Chupacabra". Come to think of it, there is no better name for a R1200GS!

Oil in Carbs. I am assuming that the leakage is because of how the crank venthose feds back into the air box. (just an assumtion). That was one of the reasons why I was thinking of routing the vent hose to a catch can or to the ground (with filter on it).

I purchased the UNI-Filter (Foam) for the standard airbox that I am retaining. I'll post pictures when the bike is completed.

[Solo_Lobo]

Oil in Carbs. I am assuming that the leakage is because of how the crank venthose feds back into the air box. (just an assumtion). That was one of the reasons why I was thinking of routing the vent hose to a catch can or to the ground (with filter on it). .


I pulled the the stock rubber lines off of the "T" fitting the goes through the airbox on the way up to the breather, then wrapped green scrubbie pads onto each side of the "T", used zip-ties to seal the end, and another to secure to the "T" fitting...

No oil found in the airbox yet, seems to work fine and doesn't force any oil/grunge into the carbs.

[robsryder]

Some experiments of various air filtration systems have been conducted with the results reported on the cited websites.

http://www.bobistheoilguy.com/airfilter/airtest1.htm
http://www.bobistheoilguy.com/airfilter/airtest2.htm
http://www.bobistheoilguy.com/airfilter/airtest3.htm

http://home.stny.rr.com/jbplock/ISO5011/SPICER.htm

After examining these websites you may wish to reconsider using K&N air filters.