1983 BMW R100RS Rebuild: Diagnose and Replace Failed Neutral Switch

When I bought the bike in January 2015, the neutral bulb didn’t light and the starter motor wouldn’t work unless I pulled the clutch. I need to figure out what is going wrong in the starter circuit and the neutral switch. I wrote up the work I did here including how I diagnosed that the neutral switch failed and how to replace it:
This write-up makes use of some short videos to show what I do. I’m experimenting with how to use video clips to explain things better than just pictures and text can.
There is a longer video at the beginning in which I explain how I use the Haynes wiring diagram and Bob Fleischer’s material to figure out how the neutral and clutch switches work in the starter switch circuit.
I’ve heard fellow Airheads tell me electricity is confusing and a mystery. So I thought maybe showing how I try and figure out how components work from the wiring diagram when I have a problem may be of some value.  Here is a direct link to that video.

Here are the other short videos I shot that are included in the write-up.

Here are a few pictures from the write-up.

Neutral Light Not Lit

Neutral Light Not Lit

Printed Circuit Contacts for Neutral Switch

Printed Circuit Contacts for Neutral Switch

Neutral Bulb Pins on Printed Circuit

Neutral Bulb Pins on Printed Circuit

Neutral Switch with Grunge

Neutral Switch with Grunge

Degreased Bottom of Transmission and Engine Oil Pan

Degreased Bottom of Transmission and Engine Oil Pan

Prying Out Center Engine Mount Spacer

Prying Out Center Engine Mount Spacer

Old Switch Ready to Remove

Old Switch Ready to Remove

New Neutral Switch and New Washer/Spacer

New Neutral Switch and New Washer/Spacer

New Neutral Switch with Plast-Aid Applied to Prevent Leaks

New Neutral Switch with Plast-Aid Applied to Prevent Leaks

Neutral Light Works Now :-)

Neutral Light Works 🙂

BMW Fairing Plastic Repair with Plast-Aid

My R1150-RS had a minor tip over, but it broke the upper fairing and also cracked one of the tabs that the left, front turn signal screws into. 🙁

Cracked Upper Fairing

Cracked Upper Fairing

Broken Tab for Turn Signal Mounting Screw

Broken Tab for Turn Signal Mounting Screw

I used Plast-aid to attach the wiring bulk head connector in a Windjammer II fairing with great success. Vetter used ABS plastic in the Windjammer fairings. I believe BMW is using ABS or a similar plastic for the body work, so Plast-aid will work well with it. It worked so well on the R1150-RS repair that a few months later, I used it to repair a number of cracks in BMW touring cases (aka, Krauser panniers).

Repairing Broken Screw Tab

I use a washer to help reinforce the srcew tab. Plast-aid will mechanically bond to steel, particularly if it has been roughed up with 100 grit wet/dry paper.

Tab Piece, Washer for Reinforcement and Mounting Screw

Tab Piece, Washer for Reinforcement and Mounting Screw

I mix up a small amount of Plast-aid. It changes consistency as the chemical reaction progresses. I wait a minute or two until it is the consistency of pancake batter. While I wait, I put some of the liquid component on the edge of the tab and the remaining edge on the fairing to promote good adhesion. When the Plast-aid has stiffened a bit, I put some on the edge of the broken tab. I hold it against the remaining tab surface of the fairing until it stays put, about 2 more minutes. I use the rest of the Plast-aid, smear some on the washer and the apply it to the back side of the tab for reinforcement. I hold this in place for another couple of minutes and I’m done.

Reinforcing Washer Glued On

Reinforcing Washer Glued On

Repairing Cracked Fairing

The fairing crack repair needs reinforcement. I use a small piece of fiber glass mat and shape it to fit behind the crack. There is a small brace above the crack that reinforces the other screw hole for the turn signal and I anchor the fiber glass against it and down across the crack.

Fiberglass Cut to Size For Reinforcement

Fiberglass Cut to Size For Reinforcement

I mix up a larger amount of Plast-aid and apply some of the liquid component along the edge of the crack to improve adhesion . I put some on the edge of the crack, aline the edges so they are tight and put some masking tape over the crack to hold the pieces together.

Masking Tape to Hold Edges Together

Masking Tape to Hold Edges Together

I put the fiber glass into the Plast-aid when it is the consistency of Elmer’s Glue to soak some into the openings of the fiber glass. I put it on the back side of the fairing, and add some more Plast-aid using a Popsicle stick. I have to hold the patch in place for a minute or so using a finger and the Popsicle stick. When it becomes very firm and the fiber glass stays put, I’m all done.

Plast-aid Soaked Fiberglass On the Back Side of Crack

Plast-aid Soaked Fiberglass On the Back Side of Crack

Here is the final repair. It will need to be sanded, some bondo used to fill in the scratches and painted. But that’s a job for another day when I setup my temporary paint booth again.

Final Repair-Just Needs Painting

Final Repair-Just Needs Painting

1983 BMW R100RS Rebuild: Pannier Plastic & Latch Repair

In 1983, the R100RS came with BMW branded panniers, or saddle bags. Mine have a number of cracks and a broken lid hinge. While I’m waiting for some fork parts to come, I started to repair the panniers. My goal was to try and make the crack repairs invisible.  I think I got a B+ this time and learned a lot about how to create the textured surface in the plastic on the outside of the pannier.

I’ve tried a plastic repair product, Plast-aid, before to fix the bulkhead connector on a Windjammer fairing. I’m using it on the panniers. It can be colored using Acrylic paint so the Plast-aid color will match the black panniers.  I also fixed a broken latch assembly and learned about locks and keys and how to figure out what key you need for a lock. Here is the link to the write-up on what I did.

I discovered that two different keys are not enough for all the pannier locks. Some have been replaced so I have four different locks needing four different keys. I posted a note to the Micapeak  Airheads forum about this and learned that the latch locks are no longer available, but, Larry Stonestreet, owner of Stoner’s Beemer Stash [[email protected]; 951-813-1704]  has the keys I need. So all’s good. There is a nice page on Bob Fleischer’s site about the locks and keys BMW has used with part numbers of the various keys.

Here are some pictures from the write-up.

Double Latch Cracks

Double Latch Cracks

Mulitple Corner Cracks

Crushed Corner With Multiple Cracks

Double Latch Crack Final Repair

Double Latch Crack Final Repair

Crushed Corner Final Repair

Crushed Corner Final Repair

Plast-Aid and Black Acrylic Paint for Tinting

Plast-Aid and Black Acrylic Paint for Tinting

Round Dremel Bit for Widening Back of Crack

Round Dremel Bit for Widening Back of Crack

Dremel Engraving Tool #106-A Bit Too Big

Dremel Engraving Tool #106 to Etch Texture Into Plastic-A Bit Too Big, #105 Is Better

JB Weld Applied to Lock Mechanism Hinge Plate

JB Weld Applied to Lock Mechanism Hinge Plate

Pannier #1 Latch Locks Use Key #069

Pannier #1 Latch Locks Use Key #069

Panniers Mounted

Panniers Mounted

Panniers Mounted

Panniers Mounted

Panniers Mounted

Panniers Mounted

1983 BMW R100RS Rebuild: Replace Choke and Throttle Cables

When I did the inspection of the bike, the throttle and choke cables looked pretty worn with kinks showing in the outer armor. The Bowden connector rubber boots are disintegrating. I’m replacing the cables before riding the bike as I don’t want a stuck throttle or broken cable to happen. I found removing the cables from the Bowden connector required a little technique, but once I figured this out for the choke, the throttle was done pretty quickly.

Here is the procedure I followed:

Here are a couple before and after pictures.

Choke Lever Removed from Housing

Choke Lever Removed from Housing (Note Broken Strand in Choke Cable)

Choke Bowden Connector on Left Side

Choke Bowden Connector on Left Side With Disintegrating Rubber Boot

Choke Cable Part Numbers

Choke Cable Part Numbers

Assembled Choke Bowden Cable

Assembled Choke Bowden Cable

I’m completing a front fork rubber cup replacement and check of the fork alignment. I hope to post that soon. After that, I think the bike is ready for my first ride.

1983 BMW R100RS Rebuild: Bing Type 94 Carburetor & Karcoma Petcock Rebuild/Refinish

You know, being retired just seems to leave no time to work in the shop. I end up doing all sorts of things and the next thing you know, time for bed.  Anyway, I finally wrote up the Bing carburetor rebuild/refinish work I did on the 1983 R100RS project.

When I rebuilt a 1973 BMW R75/5, I covered the procedure I used to rebuild the Bing type 64 carburetors, which are 32 mm, and the Karcoma petcocks. The R100RS has type 94 carburetors that are 40 mm and the Karcoma petcock outlet is 90 degrees from the inlet instead of directly underneath the inlet as for the R75/5. After 10 years, the designs are essentially the same, but there are some differences which I cover in the procedure write-up.

Here is the link to the R100RS Bing type 94 rebuild/refinish procedures.

The R100RS write-up contains links to the R75/5 procedures for the Bing type 64 carburetor and notes any differences or changes in how I did the work on the R100RS carburetors. Here is the link to the R75/5 type 64 carburetor rebuild/refinish procedures.

The combination of these two write-ups covers the type 64, 32 mm (64/32/10, right side and 64/32/9, left side) and the R100RS type 94, 40 mm (94/40/114, right and 94/40/113, left) carburetors.

I hope this material makes it straight forward for folks to rebuild these carburetors who may have been afraid to tackle a carburetor rebuild. Here are some before and after pictures of the carburetors.

Before Rebuild/Refinish

Before-Left Carburetor

Before-R100RS Type 94 Left Carburetor

Rusty Screws and Cap on Dome

Engine Side of Carburetor

Grunge and Fuel Stains

Float Bowl Removed

Float Bowl Removed, Missing Paint on Emblem

After Rebuild/Refinish

Engine Side of Restored / Rebuilt Carburetor

Engine Side of Restored / Rebuilt Carburetor

Top Side of Restored / Rebuilt Carburetor

Top Side of Restored / Rebuilt Carburetor

Outlet Side of of Restored / Rebuilt Carburetor

Outlet Side of of Restored / Rebuilt Carburetor

Carburetor Mounted - Clean

After-R100RS Type 94 Rebuilt and Refinished Carburetor