Cafe racer conversion

porkosridesabmw · May 24, 2006

Hello everyone,

My baby is a 1986 R80. I am currently starting a cafe racer conversion on her, and would like to know the following.

I am thinking of removing the airfilter box and just putting on individual filters ( cone style ) from the carbs. Can anyone give me pros / cons on this change.

Thanks in advance,
Dale

The_Veg · May 24, 2006

You'll probably need to make some new arrangement for the cankcase breather output (I've heard of running a tube to a catch-bottle). Also, since you're changing the intake tract you may see a change in performance in certain parts of the RPM range. Hard to say what changes and you may have to experiment with different filters and carb settings to make it work to your liking.

mika · May 24, 2006

The issues you will run into are mainly two. The first is the change in filter and finding individual filters that meet your needs to keep the intake clean. That is not a big deal. The second is adjusting your carbs to the change in air intake. The air fuel ration will change and you will have to either spend some time on a dyno or play with it some. There are several sites that can help.

Make ceratin you post pictures of the final product.

les_garten · May 24, 2006

porkosridesabmw said:
Hello everyone,

My baby is a 1986 R80. I am currently starting a cafe racer conversion on her, and would like to know the following.

I am thinking of removing the airfilter box and just putting on individual filters ( cone style ) from the carbs. Can anyone give me pros / cons on this change.

Thanks in advance,
Dale

Is your bike a Monolever or Twin Shock?

Les

pedrocasper · May 24, 2006

Cafe

I believe the 86 R80 has a fresh air/pure air system, which feeds back into the air box (my 84 R100 does). You will want to plug that system. Internet BMWriders has a great article on how to do it. Follow the link.

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

pedrocasper · May 24, 2006

porkosridesabmw said:
Hello everyone,

My baby is a 1986 R80. I am currently starting a cafe racer conversion on her, and would like to know the following.

I am thinking of removing the airfilter box and just putting on individual filters ( cone style ) from the carbs. Can anyone give me pros / cons on this change.

Thanks in advance,
Dale

ohh,...I am in the middle of a cafe conversion. See the pic of my R100 on the link (Airhead photos p.19 (bottom blue and white bike)). I now have EPCO pee shooter mufflers and progressive shocks and fork springs. I plan to remove the airbox and do a bit of other things during the winter months...

http://forums.bmwmoa.org/showthread.php?t=2140&page=19&pp=15

dlearl476 · May 24, 2006

porkosridesabmw said:
Can anyone give me pros / cons on this change.

Thanks in advance,
Dale

They'll get in the way of your feet.

porkosridesabmw · May 25, 2006

dlearl476 said:
They'll get in the way of your feet.

I was at a stop light and looked down, that was the first thing I thought of....!
Funny.

porkosridesabmw · May 25, 2006

les_garten said:
Is your bike a Monolever or Twin Shock?

Les

Monolever Les.

les_garten · May 25, 2006

Exhaust

porkosridesabmw said:
Monolever Les.

Hi,
I am getting ready to post a 2 into 1 Stainless supertrap Exhaust system on Ebay. It may work nice Nice on your Cafe Racer. Total System, Headers, Collector, Supertrap Muffler. Depends on the Look and noise you're going for!

Les

blake · May 25, 2006

i had an r90 with the luftmeister block off plate and k&n cone filters straight off the carbs. it looked cool.

its hard to get the filters to stay on the carbs when your boots keep hitting them. i remember one trip where a friend kept riding in front of me just so he could stop and pick up my left filter that i kept knocking off.

i also had a hard time keeping them oiled well enough to survive a serious ride in the rain. i'd get a bit of stumbling at times if i rode in a heavy downpour. i made some shields out of soda bottles and duct tape one time that only left them open to the rear and it helped, but looked really awful.

porkosridesabmw · May 25, 2006

Thanks for all of your responses guys!

I'll post a pic before the conversion.

Dale

RUSTYJC · May 25, 2006

pedrocasper said:
I now have EPCO pee shooter mufflers.....

I'm getting a mental picture..... :bolt

Rusty

kbasa · May 25, 2006

Is airbox volume really a restricting factor? That's the only reason I could see to move away from it.

blake · May 25, 2006

i'm sure people will say its about weight, but i'd wager its more about looks. if weight was a concern they wouldn't be on a bmw to start with. :stick

KBasa said:
Is airbox volume really a restricting factor? That's the only reason I could see to move away from it.

R90S · May 25, 2006

Air filters

I've done this a couple of times.

Check out the album:

http://tinyurl.com/resef

Changing th air intakes only makes sense if you change the carbs, and the rest of the engine, to suit. You'll need to make a engine breather system: it's not difficult.

When you run rearset foot controls you have plenty of foot clearance.

Later,
Jon-Lars

porkosridesabmw · May 25, 2006

just the looks, definately NOT the weight. I want to strip it down and have it as "clean" looking a spossible.

I'm eventually going to put rear-sets on it as well, so I don't think the air filters will get in the way of my feet.

Dale

porkosridesabmw · May 25, 2006

Jon,

Your bikes are an inspiration. I love the style, it's excatly what I'm going for ( in my own way of course ). I may have some questions along the way!

Best regards,
Dale

VANZEN · May 29, 2006

airbox

Air-box and snorkels on the 86 were a lot about BMW trying to maintain the performance standards of the mid 70s R90S, and still satisfy EPA regs.
The long intake tracks / snorkels served to bump up torque delivery and compensate for some lost HP.

Individual filters, and, for that matter, short intakes, are good at max rpm
to get max HP - which is why they are often seen on Vintage Race Bxrs - AT THE TRACK. Around town tractability and low end torque will suffer slightly.

Placing individual filters out of harms way can be tricky but can certainly be done - rearsets do solve the problem readily.

Don't go playing with jets if filters are the only change made.
Run stock jetting and see how they're working first. My guess is stock jets will be just fine since without additional changes, the engine is still pumping the same amount of air / fuel.

my 2?ó

check out my site for cafe ideas:http://www.rockerboxer.com

28796 · May 29, 2006

Personally I think the K&Ns would be wasted on the stock Bings. Pick up a pair of Dellortos or Mikunis if you want some performance gains. I'm just finishing up a resto/mild customization of an 87 R80. Along with new paint & polished wheels I installed a Siebenrock 9.5/1 1000cc piston/cylinder set, moved the ignition switch back into the headlight, went with a complete Epco exhaust & later this week it will get a pair of 34mm Mikunis. I prefer to tie the aftermarket carbs into the stock airbox on the boxers as I'm not into rearsets & I think its a cleaner look.

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