1977 BMW R100RS Refinishing and Rebuilding Master Cylinder and Calipers

I refinished and rebuilt the master cylinder and calipers. You can read about how I did the work here:

This bike had the blue front calipers and the ATE front disk brakes with the drum rear leading and trailing shoe brakes. Originally, the wheels were wire spoke but a previous owner upgraded them to the later snowflake wheels.

As Purchased with Later Snowflake Wheels

As Purchased with Later Snowflake Wheels

Calipers Showing Anodized Blue Fading

Blue Anodizing on Calipers Has Faded

I rebuilt the two front calipers, the master cylinder and replaced the rear brake shoes. The blue anodized calipers had faded so I had them anodized, but this was a dismal failure. Either the shop who did the work botched it or it’s not so easy to anodize old parts. I found a paint that replicates blue anodizing. I stripped the botched anodizing and painted them. I like the result.

I replaced the lower steel brake line that goes between the caliper and the union that is inserted into the lower front fairing with stainless steel lines from Rocky Point Cycle. I replaced the rubber lines with braided steel lines with a translucent blue cover and chrome unions from Spiegler Performance Parts.

Here is the finished product. When the fairing comes back from the paint shop (soon, real soon now 🙂 ) I’ll connect the upper steel lines to the braided steel line through the bushing in the top center fairing panel.

Refinished and Rebuilt Calipers Installed in Fork Lowers

Refinished and Rebuilt Calipers Installed in Fork Lowers

Speigler Braided Steel & Rocky Point Cycle Stainless Steel Caliper Line

Speigler Braided Steel & Rocky Point Cycle Stainless Steel Caliper Line

Refinished & Rebuilt Master Cylinder Mounted on Spine Tube

Refinished & Rebuilt Master Cylinder Mounted on Spine Tube

1977 BMW R100RS Replace and Adjust Wheel Bearings

A lot has been written about the procedure  to correctly set the wheel bearing preload. There is more than on technique for determining the correct preload. And wheel bearings can fail if the preload is set too low or too high. For that reason, I’ve put off setting the preload for many years and had a shop or Woody’s Wheel Works do it. But on this project, working on the wheel bearings was one of the items I had on my “Learn New Skills” list, so, now’s the time.

You can read about how I did this work here:

This bike does not have the original spoke wheels. Instead it has the cast aluminum alloy “snowflake” wheels that came latter. The rear snowflake has a drum brake while later versions of the snowflake rear wheel have a rear disk brake on the left side.

"10 Foot" View Showing Later Snowflake Wheels Installed

“10 Foot” View Showing Later Snowflake Wheels Installed

It seems that airhead wheels are a component that BMW changed a lot over the life of the airhead bikes. Further, parts fiche diagrams are notoriously confusing and frequently show incorrect parts. As I tried to get solid information about my wheels, one sage, long time wrench advised me to just inspect the parts that are there and replace what’s worn.

That said, these wheels had parts that took me some time to figure out. First, the snowflake drum rear wheels were only available with an aluminum hub in 1978. Later versions had a steel sleeve in the hub that the rear wheel bearing outer races fit into. This is an improvement as the aluminum hub to steel race interference fit was prone to allowing the race to spin in the aluminum hub which leads to a mess not to mention it can lock up the rear of the bike if the bearing seizes to the axle.

My drum snowflake rear hub has a steel sleeve as shown below. The inner edge of the hub is magnetic and you can see the line between the inner sleeve and the outer aluminum of the hub.

Rear Wheel Hub Has an Inner Steel Sleeve

Rear Wheel Hub Has an Inner Steel Sleeve

I used the spring scale method to determine the preload. This is a simple technique that is precise enough.

Pull Gauge and String Wrapped on Axle Spacer Tube

Pull Gauge and String Wrapped on Axle Spacer Tube

I had the wheels powder coated as well.  Here they are with the new wheel bearings installed and adjusted.

Rear Wheel Ready To Roll

Rear Wheel Ready To Roll

Front Wheel Ready to Roll

Front Wheel Ready to Roll

Maryland Airheads SuperTech 2.2

Out of the blue last November, I received an email from Maryland Air Marshal, Will Andalora, asking if I would be willing to be their special guest at the 2017 SuperTech 22.  To say the request was unexpected is an understatement. I called Will and after he assured me there was no mistake, it was me they wished to invite, he talked about his expectations and I accepted the invitation.

Will encouraged me to come out early so I could see some airhead sites before SuperTech started on Friday night. So, on Wednesday morning, I flew from my home in Colorado to Baltimore where Mark Lipschitz picked me up and took me to his home. I met the merry band of Maryland airheads who put this extravaganza of Air Head goodness together; Will Andalora, Mark Lipschitz, Bill Lambert, Jim McKinna. Also joining us was Chris Kennedy who puts on the “Techno Barn” Tech Day. They came over to Mark’s house where we enjoyed home cooked specialties of the house. By the end of the evening, I felt like family.z

Thursday was set aside to visit two museums catering to BMW motorcycles, ephemera, lore and to experience the passion of those who love collecting all things BMW Motorad and hearing the stories of how they came by the many items they had collected. The first stop was Jim Hopkin’s home. Jim has pursued photographs, clothing, pins, badges, trophies, bikes, toys, sculpture, and paintings all accompanied by fascinating accounts of his hunts around the world for this cornucopia of BMW motorcycle objects. Jim has one of the original M2B15 flat twin BMW engines supplied to the Victoria motorcycle company for use in their KR 1 motorcycle in the early 1920’s, letters, awards and trophies from racing legends, women riders and racers, and those who guided the destiny of BMW’s motorcycles.

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BMW First Flat Twin Engine-M2B15 Used by Victoria in Their KR 1 Motorcycle

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1920’s Race Leathers

airheaeds pre super tech
Motley Airhead Gang Poses at Jim Hopkins’ Museum for A Group Mug Shot

Here is a slide show of the pictures I took at Jim’s place.

And a short video of a neat toy BMW that reminded me of toys I played with in the 1950’s.

And a video of a distinctive sculpture Jim commissioned. The artist uses junk from automobile junk yards.

We then met Bob Henig, owner of Bob’s BMW, for lunch followed by a tour of his museum. Bob’s collection of BMW motorcycles is on two floors. I’m working on rebuilding a 1977 R100RS and he has one in his collection so I took some photos of the details I wasn’t sure about.

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Bob Henig Leading the Way into His Vintage BMW Museum

Bob has an R32, several famous race bikes, iconic models and even a single wheel MV Agusta.

First BMW Bike, Model R32
1925 R32 in Front of the Iconic K1

1984 Krauser MKM 1000/4
1984 Krayser MKM 1000/4

1970 R75/5 Land Speed Record Bike
1970 BMW R75/5 Land Speed Record Bike

1950’s MV Agusta 60 cc Monomoto Superleggera
1950’s MV Agusta 60 cc Monomoto Superleggera

Here is a slide show of the pictures I took at Bob’s museum.

Friday afternoon was spent setting up for SuperTech at the Tuckahoe Steam and Gas museum including unloading all the cut-away models Bob Sipp brought and getting a guided tour of the machine tools museum. This collection goes back to the beginning of the 20th century. The tools work and many are powered by overhead shafts with belts and pulleys.

Site of SuperTech 2.2 Meeting
Tuckahoe Steam and Gas Association Facility in Maryland-Home for SuperTech 2.2

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Just a Few of the Many Machine Tools in the Working Museum

Here are two short videos of the inside of the machine shop. The second shows the overhead shaft and pulley system operating.The overhead shaft and pulley system used to distribute power to the old machine tools that did not have separate electric motors. This was a common method of distributing power in factories at the end of the 19th and early 20th century.

SuperTech has a fantastic collection of cut-away models. This is just one them, a beautifully done cutaway of a Bing carburetor.

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One of Three Bing Carburetor Cut-away Models Bob Sipp Brought

Friday evening starts the festivities for the 65 attendees who came from as far away as California with pizza, BYOB, lots of introductions, conversations and a short presentation about how my motorcycling life led me to start rebuilding airhead bikes in earnest in 2009 and documenting the work on my web site, “Motorcycles and Other Musings”.

Some of the Airhead State Flags From Those in Attendance
State ABC Flag Display

Friday Night Pizza & BYOB
Friday Night at the Hotel for Pizza, Beer and Comradery

The format for Saturday included technical, product and riding adventure presentations. The new Kat Dash instrument flex-boards (Kat and Paul Connell), how ethanol affects our bikes (Bill Lambert), the mental preparation for a good ride (Mike Friedle), understanding electricity and wiring systems (Bill Dudley), high mileage riding (Ed Fule), stump the expert (Tom Cutter), a seminar on the on-board toolkit, bike parts and roadside flat tire repair.(Will Andalora), bringing an R75/5 back to life (Dave Fish), details about new replacement wiring harness (Todd Millican) and the story behind the “Motorcycles and Other Musing” web site (Brook Reams). Dinner was served, BYOB was consumed and conversations broke out like daffodils after the spring thaw.

Me and Ed Fule with Our Presenter Aprons
The Author and Ed Fule Wearing Presenter Aprons and Enjoying the Spring Day

Paul and Kat Connell Making Their Presentation in Stereo
Paul and Kat Connell’s Presentation Was in “Stereo”

Dave Fish Rode This Bike To SuperTech
Dave Fish Rode his Presentation Bike to SuperTech

Sunday morning started off with a presentation by Jim Hopkins of the story behind his museum. He captured the imagination and commanded the complete attention of everyone in the room with his slides and storytelling.

Jim Hopkins Presentation on His Museum and His Passion
Jim Hopkins’ Stories Command the Rapt Attention of the SuperTech Audience

At the wrap up, the coveted Dung Beetle award was presented to our Airstore manager Dave Cushing.

Coveted Dung Beetle Award
The Coveted Dung Beetle Award

This is a slide show of pictures I took during SuperTech 2.2

1983 R100RS Repair Instrument Circuit Board Foil

One indicator bulb in the instrument housing was not lighting. I pulled the instrument cluster out and tested the bulb which was good. However the foil trace that goes on the tab inside the hole in the circuit board the bulb holder plugs into had broken.

Tab Bulb Connector Lead Touches-Copper Foil Missing

The Tab The Bulb Holder Lead Touches-Copper Foil Is Missing

I used some copper foil to make a repair and I documented how I did it here.

The same technique can be used to repair any of these boards when a cracked or broken foil trace causes intermittent or complete bulb failure bulb. But sometimes the circuit board is broken, badly corroded and it isn’t salvageable.

BMW no longer sells the circuit board but you can find used ones for sale on eBay and some are in good condition. However someone took the time and effort to design a replacement light housing and circuit board that uses LED lights instead of the original incandescent bulbs. For a badly damaged circuit board where the simple fix I made is insufficient, these replacement boards will likely do the trick. I’ve not had occasion to install one of these, but you will find information about them here:

1977 BMW R100RS Bing Type 94/40 Carburetor Rebuild-Refinish

This is the fourth set of Bing CV carburetors I’ve completely rebuilt. This is the link to the current work on the 1977 R100RS that uses the Bing 94/40 model of carburetors and specifically the 103-104 series used on the 1977 “CFO” engine version of the R100RS.

The previous rebuilds include the smaller 64/32 series used on the R75 series /5, /6 and /7, and the R90/6 bikes and the larger 94/40 series used on the later R100 model bikes. I documented the procedures of the earlier work in the following write-ups.

As is often the case, I found the o-rings were hard and brittle and in one instance I found two o-rings on the idle fuel jet! The internals were pretty clean so I someone cleaned the carburetors and for some reason added an o-ring instead of replacing it on the idle fuel jet.

I decided to shoot some short videos to demonstrate how I understand the way the Bing CV carburetors work. Each video covers one of the four major functions, or circuits, used in these carburetors. The operation of the model 64 and 94 CV carburetors is the same.

Constant Velocity Circuit Operation

Here is a short video showing how the constant velocity circuit works.

Main + Needle Jet Circuit Operation

Here is a short video showing how these components work in the main+needle jet circuit.

Enriching Circuit Operation

Here is a short video showing how the enriching circuit works.

Idle Circuit Operation

Here is a short video showing how the idle circuit works.

Here are some pictures of the completed carburetors.

Refinished Outside

Refinished Outside

Refinished Inside

Refinished Inside

Refinished Back

Refinished Back

Refinished Front

Refinished Front

Refinished Top with Added Rondel

Refinished Top with Added Rondel