Best Models and Years R90/100 for Cafe Build?

I'm beginning a search for a donor bike for a custom cafe racer build of an R90 or R100. Does anyone have thoughts on those bikes in roughly 1977-83, what years or submodels were good, had problems, etc?

Naked as possible

I think if your going to make a bike something it was not it is more important to find one with good parts (Frame, engine, etc). and not be too concern about which one.
These are on MOW

http://www.bmwmoa.org/flea/detail.php?siteid=39013&catid=1

http://www.bmwmoa.org/flea/detail.php?siteid=38749&catid=1

http://www.bmwmoa.org/flea/detail.php?siteid=38616&catid=1

77-83 are all R100 series bikes. R90s ran from 74-76 (USA dates). each year had (very) slight upgrades that made the newer one slightly more desirable- more frame neck gusseting, electronic ignition, etc. 77/78 model years had most engine performance of any of them.
if you're going to chop something up, better to work on a stocker that is in need of extensive work anyway, rather than bastardizing a superior example.

Thanks to both of your for your helpful suggestions.

matthewburgess said:

I'm beginning a search for a donor bike for a custom cafe racer build of an R90 or R100. Does anyone have thoughts on those bikes in roughly 1977-83, what years or submodels were good, had problems, etc?

Click to expand...

well if those are the years you are looking for then you've taken the 900s out of the picture in place of R80s. I've seen quite a few R80 cafes, many that have been converted to 1000s (which may be an option you'd like to keep open).

I have to agree with MIAirhead's comment in that you really just want one with a good frame and engine as many of the parts on these bikes are interchangeable. My 75 90/6 actually has a /7 tank on it, though the aftermarket is awash with alternate tanks, and seats, and exhaust options. Check Snowbum's page because says pretty much everything there is to know about the various changes and problems on the airhead models throughout the years, it's a lot to read but worth it.
http://bmwmotorcycletech.info/technical-articles-list.htm
I just had to replace my clutch and while I was "in there" among other things, I sent out the flywheel for lightening, you may find that you'd want a later model airhead with a clutch carrier instead of a flywheel to avoid all that. You might want Nikasil cylinders instead of iron lined ones, you might want an electronic ignition or a kickstart. These are all things to consider.


I've done a mild cafe treatment to my bike that was a result of me just adding (or subtracting) features to fit my riding style. I prefer a forward riding position and most of my riding is either done at speed on the highways commuting or along backroads, I've never "toured' on it, but even with my sportier modifications I think I probably could with my tank bag. The clip-ons work perfectly for me and the SJ reinforced triple clamp really does improve handling a little. The seat allows me to tuck in much easier and has a cowl for support. I'm too tall to run rear sets without cramping my legs, so when I am tucked in I look like Schorsch Meier more than a cafe racer, but because I have a single seat I eliminated the rear pegs. I eliminated the turn signals mainly because the bike never had front ones and the plastic casing on the rear ones broke, but I feel the bike does look more streamlined without them and I have no problem using hand signals regularly. I kept the full fenders because I ride in the rain or when roads are wet - this is the same reason I kept the clamshell filter housing (though I drilled it for cooler air, not more air). I eventually will put on the dell'ortos and 336 cam that are on my shelf, but the rest of the bike is dialed in so well right now I've held off.



Point is, think of what you really want out of the bike you want to build. My R90 is my only bike so it has to wear many hats between being a sporty, pleasure bike to daily commuter, to all weather, all season runner. Seriously take a look at Snowbum's page to see all the various changes between years, but I think an R80 might be up your alley, and like I said, it's easy (albeit somewhat expensive) to convert it to a 1000.

I forgot to mention to think about how much you want to spend on this project. The older it is the more likely it is things will need replacement. On my 75 R90/6, build date 11/74, I've had to rebuild the final drive, replace the pushrod tube seals, neutral switch, rear brake light (housing was brittle and cracked) and other odds and ends right off the bat (actually within about 6 months of ownership). The alternator rotor went this year, I now have a spare waiting in the wings. My clutch just started to slip a couple weeks ago and found it to be well worn (down to 3.9mm!), and because of that (and because I am getting my flywheel lightened), I went ahead and replaced the rear main seal (it was weeping anyway), oil pump o-ring, transmission input shaft seal (looked like there was a little weeping but couldn't tell, figured better safe than sorry), pulled the clutch pushrod and realized the felt that was supposed to be on it was eaten up by the trans at some point in the bike's life. I had to weld the subframe which cracked along the factory weld below the seat last year, etc. etc.

These are all things that will have to be addressed with an old bike, but likely more with an older one or one that hasn't been ridden regularly.

Look for a 1985-on R100, snigle swing arm bikes make awesome cafe bikes, here is a pic of a 78 r100 I built