'92 R100R and a potential airhead

thedqg · Jun 29, 2017

Hi all,

My name is Arthur and I'm new to the world of airheads, but not to vintage motorcycles. I have my eye on a 1992 R100r that I may be acquiring over this weekend. I have been doing some research on the r100r as far as what issues to expect. So far I have identified:

1) Potential missing circlip
2) The $2k O-ring
3) Potential weak charging system

Any other issues I should keep in mind or look out for when inspecting the bike?

I also understand the '92 model has a single disc braking system- would it be too much trouble to add another disc and bremco brake caliper? Or will I have to get a latter year wheel?

Many thanks in advance!

20774 · Jun 29, 2017

Welcome to the forum! My thoughts:

1) Yes, no circlip but it's not going to blow up on you and you can monitor the fuzz on the drain plug to get advance warning of any issues.

2) Sure, but once you have figured out the order of parts, it's no biggee...

3) If you're living in the Great White North, sure you probably won't have enough juice to run every electric warming piece of clothing. But generally, the electrical system will work fine with a bit TLC. 400+ watt systems are plug-n-play if you really need to go there.

Some of the early Airheads can be upgraded by buying the correct slider and likely making changes to the master cylinder...probably same for the '92. Try it as is and see if need more braking. The Airhead front brakes are affectionately known as the first version of ABS! Just kidding...

thedqg · Jun 29, 2017

Thanks for the welcome Kurt. I'm thinking of cafe-ing the bike and I wonder if this is the appropriate place for it, or if there's a forum or a section of the forum just for that? I was just looking through the forum trying to find resto or build threads, and couldn't find any.

20774 · Jun 29, 2017

Arthur -

No, no special section for cafes but you're certainly welcome to document your process or solicit ideas. Many people document their restorations...see threads by Brook Reams. Most around here lean more towards the original style and don't get into café-ing bikes. I think it "hurts" more when someone takes a rare-ish bike and does all kinds of things to it...when they could work with a non-runner and do the same thing. They aren't making Airheads anymore.

But, it's your call...your bike. One thing to maybe consider...keep the ability to return to it's original configuration if you can afford to hang on to the parts. Could make the bike more saleable if/when you get to that point.

Good luck!

thedqg · Jun 30, 2017

20774 said:
Arthur -

No, no special section for cafes but you're certainly welcome to document your process or solicit ideas. Many people document their restorations...see threads by Brook Reams. Most around here lean more towards the original style and don't get into café-ing bikes. I think it "hurts" more when someone takes a rare-ish bike and does all kinds of things to it...when they could work with a non-runner and do the same thing. They aren't making Airheads anymore.

But, it's your call...your bike. One thing to maybe consider...keep the ability to return to it's original configuration if you can afford to hang on to the parts. Could make the bike more saleable if/when you get to that point.

Good luck!

Thanks.. and yes my approach is going to be fairly simple, I am going to definitely preserve the "airheadness" of the bike and it would easily be restored to original if needed. Most of what I would do would be to the front end anyway.

khittner · Jun 30, 2017

I think all of the R100Rs had dual Brembo discs up front. I don't know whether there were GS-like premature wear issues with the U-joints in the street Paralevers on the Rs and Mystics, but someone with better knowledge of that detail will probably offer their insights. The GS-ish fuel tank of the standard R may have weird proportions for a cafe bike, so you might want to spring for something different there---or not.

James.A · Jun 30, 2017

Hello therqd. First off, as the owner of the aforesaid R100r, you have the right to do anything you want to do with it. There might be some participants here who are purists and can not abide a modified bike in any way. I say screw 'em.

As far as a cafe treatment, a person has to mindful of altered exhaust systems. Particularly home fabricated systems that place form over function. I have seen more than 1 cafe airhead that suffered from non-stock exhaust. The original exhaust system is highly refined and tuned to enhance and maximize the performance of the fuel system. There is really a whole lot to it beyond the simple appearance of the exhaust. I would recommend buying a copy of the "Bing" book to try to get a feeling for the finer points of exhaust tuning and fuel/air theory in general. http://www.bingcarburetor.com

1074 · Jun 30, 2017

Weak charging system

Weak charging! Well, if you're attempting to light up Wrigley Field then I guess that's true. If you're going to throw on a lot of high energy consuming lights then you might want to do the math on what you have and what you can put on safely.
On the other hand, if you're going to "cafe" it out then you're going to go with a minimalist approach. The existing system will easily power an electric vest and heated grips. If you really have to have more power then a visit to Motorrad Elektrik or EME will set you onto the path of electrical superiority!

beemerphile · Jul 1, 2017

The R100R might be, and probably is, the best airhead BMW from a technology and ride performance point of view, but it is exactly the last place I would start for a cafe bike. The aforementioned well-integrated exhaust system is double-ugly compared to the twin exhausts (and custom variants) of the earlier models. But you will likely rue the day you took it off to attach something "prettier". The tank aesthetics were mentioned - add instruments as well. The mechanicals of the rear drive are not as "clean" as the older ones either. The $2,000 o-ring applies to any of them and is probably $4,000 by now. Oil change is a simple thing to learn and there are some going in measurements to take to make sure you have sufficient o-ring crush. The charging system is fine for a cafe - maybe change to a more robust diode board.

widebmw · Jul 1, 2017

I had a 92 R100R from February of 1992 until June of 2010. I put 261,000 on it but not without some work on it. The 92 came with one front disc brake, I bought the second the next year when the stock 93's came out with them. Later I got the 400 watt alternator and a nippondenso starter. 40mm bings, fox shock. Some drive shafts, engine and transmission rebuild, more than one. I put a lot of money into it. The newer bikes are much better.

grahamm · Jul 1, 2017

Something to add to the pool...

I have a canadian/eu version of the '91 R100r and had a '91 R100GS, they both came with 40mm bings mounted. My R100r is a blast to ride

I believe the diff to the US versions where:
- 40mm Carbs
- 40mExhaust headersm - not true from Anton's comment below
- Carb cables
- no pollution control circuits

queenshorseman · Jul 1, 2017

R100r

I bought an exceptional '94 r100r yesterday with 26,000 miles on it and plan to pick it up next week. It is a one owner, dealer maintained bike. I started looking at the 81-84 years but everything I found needed significant dollars spent and the good ones were still quite expensive. I almost bought a mono lever r100rt that had the fairing removed but then found the r100r and it offered me everything I wanted in a get on a ride package. I'm located in Canada and I hope that this will be my main, "modern" bike for years to come. The paralever wear worry was the main thing I had to overcome to buy this bike but I would think nothing of changing out a chain and sprockets on other bikes so eventually I put it in perspective. I will likely research and buy a replacement shaft to have on hand for peace of mind. With our short riding season, I can only hope to wear things out on this bike!!

AntonLargiader · Jul 1, 2017

grahamm said:
I believe the diff to the US versions where:
- 40mm Carbs
- 40mm Exhaust headers
- Carb cables
- no pollution control circuits

They all had the same headers. Actually the headers quickly step from 38mm down to 36mm, pretty much at the finned exhaust nut. Supposedly the best exhaust ever on an Airhead, which I would believe.

40mm headers were a short-lived idea, in the '70s.

thedqg · Jul 1, 2017

Thank you all for your detailed input; much appreciated!

Obviously, not much in the way of cafe-ing or "freelancing" here on this forum, but certainly enormous knowledge that I can draw upon or consult, when making decisions as to where I can change something, and where/when I should leave something be.

I'm not going to make drastic changes- I want to preserve the airhead feel, but try to simplify where I can so it's a pure machine look.

As far as the exhaust, I do want to go with a two exhaust look, one on either side for a more balanced look. Will have to research this further to minimize upsetting the delicate balance as far as attaining premium performance.

EDIT: After sleeping on it overnight and rereading everything on here, I think I'll try to keep the exhaust system as intact as I can. Is there any way I could keep the 2 in 1 system but change the muffler to another high-end reverse cone type?

James.A · Jul 2, 2017

I used to own a 1988 R100RS that had a centralized collector and 2 mufflers. Something like that would give you a muffler on each side, down low, and not alter fuel system dynamics. Your R100R has a 2 into 1 exhaust? OEM? That might be an aftermarket item. Any one else know more about this than me?

khittner · Jul 2, 2017

The paralever bikes (GS, R100R, & Mystic) had OEM 2-collector-1 systems that ended on the left side (the GS, higher; the street R100R and Mystics, lower) of the bike---I assume to accommodate/bypass the more complex swingarm hardware on the right side. The entire paralever exhaust system, from the cylinder head back, differed from the the street monolever bikes' exhaust system.

thedqg · Jul 3, 2017

Well I went to look at it yesterday and as soon as I got onto it, I knew it wasn't for me. It was too modern. Now I know I want something circa 1984, so I'll be on the outlook for that. Now I know why I like that dual exhaust, dual springs look.

If anyone wants to buy a '92 r100r for a very reasonable price, PM me ASAP and I will pass on the contact info.

James.A · Jul 4, 2017

Too modern? Consider a /5. The combination speedo/tach set in to the top of the headlight shell is a thing of beauty. Retro to the max. However, if you want a kill switch on the hand set (safety feature) you will need to go 1975, /6 or later. Best of luck. Keep us posted.

lkchris · Jul 4, 2017

AntonLargiader said:
40mm headers were a short-lived idea, in the '70s.

And the dual crossovers made them irrelevant.

thedqg · Sep 28, 2017

Hi all,

I'm back- I ended up picking up a non-running '81 R100RS and will be parting out lots of it and rebuilding from the ground up. I still intend to lean towards a cafe-ish interpretation, but not too "out there." I still want to preserve what makes it an airhead.

'92 R100R and a potential airhead

New member

Liaison

New member

Liaison

New member

New member

former Airmarshal-IL

Active member

New member

New member

New member

New member

Active member

New member

former Airmarshal-IL

New member

New member

former Airmarshal-IL

Active member

New member

Similar threads