Kimjon's next money pit - BMW Airhead cafe racer build

[Kimjon]

On my wishlist for a very long time has been a BMW Airhead. Iconic bikes, especially for a base to do a cafe racer. So, now I've finished my harley its time to financially ruin myself yet one more time.

I managed to get the R100 version which is a healthy 980cc/60hp and most importantly it has the highly sought after mono shock rear swingarm. This is the best airhead bmw to choose for a cafe racer build, so I'm already off to a very good start here.

Photos of the bike as it stands now. I like what I see already, its a beautiful bike with nice clean lines and the previous owner has already made a good start, but I have my own very clear ideas on style and proportions, so I'll slowly start putting my own touch on this bike to subtly change a few things.

So watch this space, as I'll update as I go down the rabbit hole of yet another custom bike build, although this one is a much better starting point than my harley where I literally started with nothing but an idea.

[Transom]

Here’s a mates old one for inspiration Ducati style fairing and his own handmade solo seat 

[Kimjon]

2 hours ago, Transom said:

Here’s a mates old one for inspiration Ducati style fairing and his own handmade solo seat 

Pretty cool. Im more into this style

But I want really short exhausts ending flush with rear of motor. I'm going to try to work with what I've got already and not just throw $50k at it to solve problems, however I already know these projects aren't cheap. It's 90% about getting the proportions right, which for me makes or brakes any bike regardless of how much the build cost was. 

Walzwerks (Marcus Walz) in Germany is a huge inspiration of mine for both Harleys and BMW's.

https://www.walzwerk-motorcycles.de/schizzo-1/prices/schizzo-scrambler/

I'll be drawing on his ideas a lot for my build.

[crash]

https://www.bikebound.com/2020/02/25/silver-wasp/

Here's another one similar I saw some time ago. My father has a 1983-ish R100RT sitting in his shed (lapsed rego) that I jokingly threatened to strip down.  

[datlow]

21 hours ago, Kimjon said:

really short exhausts

So they have a X/H pipe as standard? 

I like this type that fits in place off 

 

[Kimjon]

13 minutes ago, datlow said:

So they have a X/H pipe as standard? 

I like this type that fits in place off 

 

Yes!!

[governorsam]

[Kimjon]

1 hour ago, governorsam said:

Yes, very much so. Excellent example.

[Kimjon]

Got it home, immediately removed the crashbars and rear fender, zip tied number plate and a few other little loose items and already looks 100% better.

Long-term plans:

Lower it by 120mm

Paint lots of stuff black

Fix exhausts 

Battery box relocation 

Tidy up headlight area

cut shitloads of superfluous brackets off the frame

Figure out footpeg placement, as for me its unworkable right now, thr cylinder heads get in the way.

Sort out the seat. Luckily its a bolt on item, so i don't need to weld anything to the frame etc.

 

Etc, etc, etc....

[SOHC]

Its funny BMWs only make max power with the stock liuftmaster mufflers, can do any mods to the engine like supercharge etc but every exhaust system under the sun wont preform as well as the stock system lol.

Wile you can slip the gearbox back and lube the clutch splines and check the flywheel bolts.

Thats the only photo I have with my BMW

[Kimjon]

Thanks for the advice, really appreciated.

Unfortunately I brought mine as is, so working with what I've got. Hard to know what the baseline is/was as I never started at that point, however its running a little rough for sure.

The exhausts on it now aren't even clamped to the headers. They're a size to big, ie the header is loosely sitting inside the exhausts with 2mm of clearance around the pipe...lol. 

I visually set the carbs, by getting approximately 1mm of throttle cable play in each slide. Its now a lot smoother than it was. So I ordered a set of vacuum guages to try balance the carbs better than they are now.

All that said...fuck yeah, this thing is fun!! Its not modern bike fast, but torque like a tractor and certainly enough power to be interesting.

 

 

[Kimjon]

its just not getting old for me. So good. Im in love with this bike, its kinda the best/worst of everything, like a buell but not as fast, has the charm of an old carburetor harley, so much fun to ride like a vespa, seating position like a dirt bike, just such a unique bike full of character, its got what makes a bike fun to ride...the X-factor.

[Kimjon]

Ordered two of these. Plan is to shorten the headers and get these sitting underneath closer to the end of the frame.

The current exhausts are deafening. So stupidly loud if offensive to my ears, and undoubtedly everyone else's too.

[Kimjon]

Ive given it a good going over, sorted out a few wiring gremlins etc. Removed a heap of stuff that didn't need to be there, swapped out fuel lines, sorted out linkages to brakes and gear shifts, fiddled with carburetors some more etc etc... Its purring now, everything is working as it should.

Actually looking pretty sweet, especially given no money spent - just my time.

I've orderd a few parts from overseas, that will tidy up the motor area. I'm relocating the battery and will probably go with a lithium one to reduce the physical size. But yeah, loving the ease of these project.

[Kimjon]

Cutting up a classic...full send

I cut the wings off it both sides. 100% better already. Huge win for zero money.

[Mitch.W]

nice, love me a BMW, i built one (build thread on here somewhere) acouple of years ago, i cut the brake light switch bracket off completely to tidy the frame up and mounted it on the frame in the peg mount so the brake pedal pulled it down, you'll find most good looking exhausts on these are silly loud, just wear ear plugs is the best solution. 

[Kimjon]

7 hours ago, Mitch.W said:

nice, love me a BMW, i built one (build thread on here somewhere) acouple of years ago, i cut the brake light switch bracket off completely to tidy the frame up and mounted it on the frame in the peg mount so the brake pedal pulled it down, you'll find most good looking exhausts on these are silly loud, just wear ear plugs is the best solution. 

Do you have a link to your build? I halfarse tried searching under your name but nothing obvious popped up.

[Beaver]

https://oldschool.co.nz/index.php?/topic/70199-mitchs-91-bmw-r80/#comment-2205313

[Lord Gruntfuttock]

pointless sharn.
got a mate who was doing an older BMW cafe racer. He designed a beaut looking tailpiece, painstakingly made reverse molds etc, and glassed up the new piece. Something went wrong with the release wax though and the whole thing was permanently stuck together. Think he gave up...

[Kimjon]

Yep, clutch cable broke. Ordred one from Germany, so downhill rolling starts only until it arrives...