Looking for a R100S - I think... Please Advise

[Ken in Oklahoma]

I'm unaware of any substantial emissions equipment added for the '78, 79, and 80 bikes. There were other changes such as valve timing changes, piston shapes, ignition advance curves, and perhaps carb jetting, which might affect emissions, but I think not to a significant (detrimental) degree. What I'm calling a significant degree happened with the introduction of the square plastic air box replacing the "clam shell" aluminum air box. I believe '81 heralded the introduction of the fresh air tube routed from the air box to the exhaust valve (to promote further burning of the gasses once out of the cylinder. That change is relatively easily disabled, but the square plastic air box looks decidedly "un-classic" IMNSHO.

I hasten to add that some very good things happened with the later bikes, especially an adequate front braking system (replacing the dratted under the tank master cylinder and the "swinging" ATE calipers on the front forks).

Many people, including myself, tend to regard any airhead as "classic", though I sometimes have to squint my eyes slightly and look between my fingers when I look at a monolever bike.

The fact is, if I could only have one airhead, and it had to be a monolever bike, I could still enjoy a fulfilling life aided and abetted by a wonderful torquey power band and finally getting rid of thosed damned hydraulic rear brakes.

Editing: Oh, and the '81 and up bikes have those wonderful Nikisil cylinders along with a light feeling but very solid clutch.

Ken

[Souljer]

Hi,

I just spoke to the seller of the red 1978 R100S.

He mentioned that the bike has manual rear brake. I heard they stopped that in '77.
He said that if it was him he would replace the push-rod tube seals. I asked and he replied they did not leak. The bike is not leaking oil, says he.
The front breaks squeak and he would have them polished or re-ground.

He said he's done all the work on the bike (he used to work as a VW mechanic) and has checked the drive spines. They look fine.

The bike has just about everything from a stock 1978 bike.
For some reason the choke is on the handle bars. Not sure why, maybe that was an extra option at the time?
Maybe the bike is a late model '77 that got sold and registered as a '78? This explaining the manual rear brake.
VIN: 6145664

He's pretty firm on the price. He feels it priced accordingly with the bikes age and condition. He might come down a few hundred but he's not that interested in doing that. He's got 4 bikes right now, 3 are BMW; this one, a toaster, and a 1200 for cruising. The other is a Ducati 851.

I'm not sure about it.
Any thoughts on your end?

Regarding newer bikes, I agree that there are improvements and that has been my beginner issue. It's just a long list through time of this is better but that is worse, back and forth. I actually like the idea of the monolever, but I like the idea of simple overall mechanics, that I can work on at home myself, more.

Some of the other things are things I (or anyone) can add and change on their own, right? For me that can happen through the years as things develop and change.

[Jean]

With the wire wheels I'd say it's a '77. Mechanical brake sorta goes along with wire wheels, BTW, on the other hand the cast wheels have been changed out by some folks just to GET A MECHANICAL BRAKE! I have the hydraulic brake on the rear and while it's working it's fine. When you have to rebuild it and bleed it, it gets to be lots (and lots...) of fun. READ other posts on this subject.
On the other hand since it has a salvage title only the MONTH and DATE on the frame plate would tell you how the registration listed it. They usually change the year starting in September of the previous year. (A september 1977 would be registered as a 1978.) My R100s (Euro) was mfg. in Sept of 1978, so the title says 1979, however it has ALL the characteristics of a '78 from the git-go. The only unusual thing is the trans, case which is ribbed. A common practice of "late" model-year bikes was and may be still, to use whatever was necessary to build-up the desired bike. Since it is a German-delivery bike, I see it the same way as the weird assemby of parts on many VWs and Mercedes I've owned.

Salvage Title: Which numbers match the title? The engine or the frame? How does that go in CA? Normally the FRAME is the title number here in SC as engines get replaced when they have "accidents" like a rod passing thru the crankcase....

PS. I AM a Mechanical Engineer. Or was. I retired in 2010...finally.

For the price, I'd tend to go with Duanes feelings. It IS nice looking, but it is "built-up" from bits.
Have you gotten your AIRHEADS Directory yet? See if someone in the Airheads lives closer to the bike and see if they would go have a look, and a ride. OR maybe meet you there to see it. It's still pretty $$$ tho, for a "collection".

[Mal S7]

I have a 77 model /7 with drum rear and wire wheels and a 78 model S (in bits) with drum rear and wire wheels. It may have been a special order though.

[Ken in Oklahoma]

I have a 77 model /7 with drum rear and wire wheels and a 78 model S (in bits) with drum rear and wire wheels. It may have been a special order though.

For what it's worth I also have a '78 R100S, the so-called "Touring" model, which means Butler & Smith imported a naked R100S and then installed a smoke red Luftmeister fairing on it. This bike has the snowflakes with the hydraulic rear brake (of course). I'm sure it's original since I bought it from the original owner who bought the bike for his honeymoon. He sold it because it spent most of its time in storage and he was tired of paying the BMW shop for cleaning carbs.

I don't know when in the model year the bike was built though.

This winter I'll be buying a smoke red S fairing from Holt BMW and will then convert it to the S configuration that BMW and God intended.


Ken

[khittner1]

A red smoke '78 R100S; you're living the dream, Ken . . .

[Souljer]

Hi,

So it sounds like the consensus is that I should pass on the red non-matching bike for the price, even if I can get a few hundred off. It's pretty and runs for now but it's not really a good deal.

Another thing I was wondering about is insurance.
What's going to happen when the insurance company reads "salvage" on the title? Will that make it more expensive or difficult to insure?

[Deleted User 287]

Mounting the choke lever on the handlebar is NBD. All that is required is a perch from a later model, and the associated hardware, cables, etc to hook it up to the carbs.
I did it to one of my bikes once. It is mostly an exercise in spending money, since you don't need to enrich both carbs to get the bike started - providing it is in a good state of tune.
A lot of folk have removed the choke cables completely in favor of a simple wire on each carb:


click for larger

[Ken in Oklahoma]

Mounting the choke lever on the handlebar is NBD. All that is required is a perch from a later model, and the associated hardware, cables, etc to hook it up to the carbs.
I did it to one of my bikes once. It is mostly an exercise in spending money, since you don't need to enrich both carbs to get the bike started - providing it is in a good state of tune.
A lot of folk have removed the choke cables completely in favor of a simple wire on each carb:


click for larger

I hate to be picky Rob, but shouldn't that carb be mounted to the rear of the head?

Ken

[Deleted User 287]

Ken

~ Being funny in Oklahoma