1983 BMW R100RS Replace Main Wiring Harness & Lengthen Handlebar Switch Wires

I’m going to replace the main wiring harness. This requires removing a number of connections inside the headlight shell, pulling the old harness out of the headlight shell and then installing the new harness and connecting the wires to the proper terminals on the wiring block, the headlight relay and the turn signal relay.¬† You do not have to remove the connections from the left and right handlebar switches to replace the main wiring harness.

Bur, since I am converting this 1983 R100RS into an RT configuration and the RT handlebars are much longer than the RS bars, the stock RS handlebar switch wires are too short; 230 mm (9 inches) vs.the RT switch’s 520 mm (20 inches). However, someone replaced the left handlebar switch with an RT length switch, so that’s fortunate. But the right handlebar switch, that was also replaced at some point, has shorter 380 mm (about 15 inches) wires; they are longer than RS wires, but still too short. Since BMW does not sell the RT switches anymore, I will lengthen the wires in the right handlebar switch cable.

Here is how I did that work.

And here are videos summarizing the procedure.

VIDEO: 1983 BMW R100RS Replace Main Wiring Harness

VIDEO: 1983 BMW R100RS Lengthen Handlebar Switch Wires

Here is the new main wiring harness I got from Euro MotoElectrics. BMW not longer makes this harness.

New Main Wiring Harness From Euro MotoElectrics

New Main Wiring Harness From Euro MotoElectrics

Here is the final product.

Both Handlebar Switches Are RT Length

Both Handlebar Switches Are RT Length

New Main Wiring Harness with RT Length Handlebar Switch Wires Installed

New Main Wiring Harness with RT Length Handlebar Switch Wires Installed

 

1983 BMW R100RS Repair, Refinish, Paint

I get questions every now and then that are along the lines, “How did you get that so clean¬† … looking like new …”. So I posted a page that I will keep updating as I go to collect information about how I repair, refinish and paint parts during this project. You can find it here:

Here are a couple before and after pictures from the work I’ve done so far.

BEFORE: Brembo Rear Brake Caliper

BEFORE: Brembo Rear Brake Caliper

AFTER: Repainted & Rebuilt

AFTER: Repainted & Rebuilt

BEFORE: Left Carburetor Top

BEFORE: Left Carburetor Top

BEFORE: Left Carburetor Choke Side

BEFORE: Left Carburetor Choke Side

AFTER: Choke Side of Carburetor

AFTER: Choke Side of Carburetor

AFTER: Top Side of Carburetor

AFTER: Top Side of Carburetor

BEFORE-Inner Timing Cover

BEFORE-Inner Timing Cover

BEFORE-Inner Timing Cover

BEFORE-Inner Timing Cover

Finished Inner Timing Cover

Finished Inner Timing Cover

Front Engine Cover with Corrosion

Front Engine Cover with Corrosion

Refinished Front Engine Cover

Refinished Front Engine Cover

Rear Drive Was Painted Black

Rear Drive Was Painted Black

Rear Drive Was Painted Black

Rear Drive Was Painted Black

Refinished Rear Drive

Refinished Rear Drive

Refinished Rear Drive

Refinished Rear Drive

 

1983 BMW R100RS Install Drive Shaft and Swing Arm Bearings

I removed the drive shaft so I can get the swing arm powder coated. You can read about how I removed it here.

Now that the swing arm is back, it’s time to install the drive shaft and new swing arm bearings.

Powder Coated Swing Arm

Powder Coated Swing Arm

I use the Cycle Works drive shaft spring compressor to install the drive shaft by compressing the spring as I did when I removed the drive shaft so I can install the new snap ring that secures all the drive shaft components on the shaft.

Cycle Works Drive Shaft Spring Compression Tool Components

Cycle Works Drive Shaft Spring Compression Tool Components

Drive Shaft Parts

Drive Shaft Parts

All Done-Rear Drive End

All Done-Rear Drive End

I installed the new sealed swing arm bearings using a large socket. I remove the dust cover and drove the bearings into the swing arm with the socket and a hammer.

Front Face of Bearing With Dust Seal

Front Face of Bearing With Dust Seal

Dust Seal Removed

Dust Seal Removed

Front Face Of New Bearing Has A Sleeve

Front Face Of New Bearing Has A Sleeve

Driving The Bearing Into The Swing Arm with Just The Socket Was Easier

Driving The Bearing Into The Swing Arm with Just The Socket Was Easier

You can read about how I do this work here:

And here are two short videos summarizing how I do the work.

VIDEO: 1983 BMW R100RS Install Drive Shaft

VIDEO: 1983 BMW R100RS Install Swing Arm Bearings

1983 BMW R100RS Install Engine Top End

The engine came with the stock 8.2:1 compression pistons. But the early RS motors came with high compression 9.5:1 pistons. The bike has 83,000+ miles on it. So I decided to install new high compression pistons. Tom Cutter at Rubber Chicken Racing Garage, told me due to the very tight piston clearances in the Nikasil cylinders and the amount of variation in piston diameter with the new pistons, the best way to proceed is to replate the cylinders with Nikasil and hone them to match the pistons to ensure proper clearance. So, I send him the new pistons, rings, wrist pins and old cylinders for this work to be done. I also had him vapor hone the cylinders to refinish them to the factory patina.

Refinished Cylinders with New Push Rod Tubes

Refinished Cylinders with New Push Rod Tubes

The other work needed was to the heads. When I tested them, the valves were leaking. So I sent the heads to Randy Long, at Long’s Mechanical Services, who is a well respected head rebuilder, for his opinion. We decided to replace the exhaust valves, all the exhaust guides, springs and keepers. I had him machine the heads for dual plugs. I have dual plug heads on two airhead bikes and I like the improved gas mileage. Randy milled the valve cover mating surfaces so they are flat and bead blasted the heads so they look brand new.

Randy Long's Rebuilt Heads

Randy Long’s Rebuilt Heads

Rebuilt Head with New Exhaust Valve and Dual Plug Conversion

Rebuilt Head with New Exhaust Valve and Dual Plug Conversion (Note Two Spark Plug Holes

Here is what I ended up with. The red tape indicates things I need to do before first engine start: install new spark plugs and put oil in the engine. The rags protect the heads from getting anything inside from the intake and exhaust ports.

Red Tape Means Not Ready Yet

Red Tape Means Not Ready Yet

All Done

All Done

Here is written documentation of the procedure:

And here is a video of the procedure.

VIDEO: 1983 BMW R100RS Install Engine Top End

1983 R100RS Install Connecting Rods & Cam Followers

I had the connecting rods inspected, reconditioned, and new wrist pin bushings installed by Tom Cutter at Rubber Chicken Racing Garage.

Connecting Rod Parts

Connecting Rod Parts

I did that since this engine has over 83,000 miles on it. As Tom said about the life of connecting rods:

“Metal parts get deformed when they get traumatized by 270 TRILLION
combustion cycles (4500 RPM, 60 MPH, 100,000 miles= 270 and more zeroes
than I have left in my computer.) Just a lotta lotta little taps will make
metal flow. In the case of connecting rods, that becomes manifested in
misaligned and ovalled bearing bores. Wristpins rock, both radially as well
as axially, which deforms the small-end bushings. That stuff needs
attention on a high-mileage engine reconditioning.”

Here is how I install the reconditioned rods and the cam followers.

And here is a short video summarizing the procedure.

VIDEO: 1983 R100RS Install Connecting Rods & Cam Followers