00 BMW 1983 R100RS Disassembly Down To The Frame

This document shows how I disassemble a 1983 BMW R100RS down to the frame. It has links to other documents that describe how to remove various assemblies such as the fairing, electrical system, brakes, etc. Although not included in this document, there are other documents that cover details about the disassembly of some of the components I show how to remove in this document; e.g., the master cylinder, disk calipers, wheel bearings, etc.

I first got the bike in 2015 and did a number of things to get it running and to correct various problems like a flickering oil pressure light and the inability to start the bike unless the clutch was pulled.

  • Rebuild carburetors and petcocks,
  • Repair oil filter pressure relief valve
  • Install new fork seals,
  • Repair odometer and clock repair,
  • Instrument cluster circuit board repair,
  • Install new diode board with solid mounts,
  • Install new alternator brushes,
  • Remove Pulse-air system.

It wasn’t until 2019 that I returned to this build. I ended up acquiring a first year, 1977 R100RS and rebuilding it. That, and some other smaller projects diverted my attention. Now, I have decided to do a restoration-modification converting the bike into an R100RT with several performance and reliability improvements.

Record Keeping

As I disassemble a bike, I keep records of what I find. I note the condition of the parts in a log. An asterisk indicates part replacement, and notes indicate any reconditioning or painting that need to be done. If I find something that I’m not sure is correct, I use a “?” so I can go back later and figure out what’s the correct part, or assembly. On past projects I have filled in 20 or more pages of notes. These are invaluable in helping keep the project organized, fleshing out the budget with parts costs, and when assembling the bike, I often pull out these notes to refresh my memory.

Parts Log with Condition Notes

Parts Log with Condition Notes

I bag the parts in labeled zip lock bags. I often bag sub-assembly parts in separate bags and put them into a larger bag with all the parts for the complete assembly.

Sub-assembly Parts Bagged

Sub-assembly Parts Bagged

Assembly Parts Bagged in Larger Zip Lock Bags

Assembly Parts Bagged in Larger Zip Lock Bags

This is a short video “walk around” of  the bike before I start disassembling it.

VIDEO: 1983 BMW R100RS Pre-build Walk Around

NOTE:
So, when I disassembled the bike, I learned the mufflers are badly rusted, so they will be replaced. 

Remove Gas Tank

The gas tank is secured by two knurled black plastic nuts under the rear of the tank and a horizontal tube with a rubber cover at the front of the tank. But, you already knew that, right? :-).

Tank Removed

Tank Removed

Remove Seat & Seat Cowling

Here is documentation about how I removed the seat and the seat cowling from the seat.

Remove Battery & Battery Box

I disconnect the battery (-) and (+) cables from the battery. Then I remove the two black plastic top battery nuts that secure the hold down strap. and pull the battery up between the sub-frame rails.

NOTE:
If you can’t pull your battery out of the frame, try removing the nuts from the two top battery box vibration damper studs. Then you can tilt the battery box toward the rear fender. This will position the battery toward a wider opening in the sub-frame and you should be able to pull it up and out.

Then I remove the nuts from the top rubber vibration damper studs that hold the box in the frame.

Battery Box Top Rubber Vibration Damper Mounting Detail

Battery Box Top Rubber Vibration Damper Stud Detail

The right side rubber vibration damper stud secures the rear master cylinder fluid reservoir. I use some garden wire to secure the reservoir to the frame so the brake fluid won’t leak

Rear Brake Fluid Reservoir Mounts to Top Right Battery Box Isolation Damper

Rear Brake Fluid Reservoir Mounts to Top Right Battery Box Isolation Damper

I tilt the box to the rear and pull the battery out. Then I remove the bottom three nuts on the three rubber vibration damper studs that secure the battery box to frame and lift it out of the bike. On this bike, the middle rubber vibration damper stud is missing, likely because the rubber cracked and it broke off.

Battery Box is Missing One Rubber Isolation Damper Stud

Battery Box is Missing One Rubber Isolation Damper Stud

Remove Nuts From Bottom Battery Box Vibration Damper Studs

Remove Nuts From Bottom Battery Box Vibration Damper Studs

There are five rubber vibration dampers with studs and nuts on each end. The bottom studs have nuts underneath the bottom battery bracket that is welded to the frame. I remove the bottom nuts to remove the vibration dampers.

The right, top vibration damper has one longer stud. This stud secures the strap around the rear master cylinder brake fluid reservoir.

Top Right Battery Box Bumper Has Longer Stud for Rear Brake Fluid Reservoir

Top Right Battery Box Bumper Has Longer Stud for Rear Brake Fluid Reservoir

(Top)-Rubber Bumper with Long Stud, (Bottom) Other Rubber Bumpers

(Top)-Rubber Bumper with Long Stud, (Bottom) Other Rubber Bumpers

Remove Windscreen, Fairing, Dash, Volt Meter, Clock, Ignition Switch

Next, I remove the windscreen, fairing, dash, volt meter, clock and ignition switch. Here is the documentation of how I did that.

Remove Headlight

I remove the headlight from the headlight shell after I disassemble the fairing. The headlight shell is the at the other end of where all the main wiring harness wires go. You can see how I did that here.

Remove Upper, Middle and Two Lower Fairing Brackets

Now the headlight shell has been removed, I can remove the two bolts that secure the upper fairing bracket to the steering head.

Upper Fairing Bracket Mounting Bolts Are Behind the Headlight Shell

Upper Fairing Bracket Mounting Bolts Are Behind the Headlight Shell

One of The Two Upper Fairing Bracket Mounting Bolts

One of The Two Upper Fairing Bracket Mounting Bolts

Upper Fairing Bracket Mounting Bolts

Upper Fairing Bracket Mounting Bolts

A long extension on a 13 mm socket does the trick.

Removing Two Upper Fairing Bracket 13 mm Bolts

Removing Two Upper Fairing Bracket 13 mm Bolts

The bolts have a flat and wave washer.

Upper Fairing Bracket Bolt Hardware Detail

Upper Fairing Bracket Bolt Hardware Detail

Steering Head Holes for Upper Fairing Bracket

Steering Head Holes for Upper Fairing Bracket

The bracket is straight with no kinks and their is no rust or tears to any of the welds.

Upper Fairing Bracket Detail

Upper Fairing Bracket Detail

Upper Fairing Bracket Detail of Welded Bracket That Fits Against Steering Head

Upper Fairing Bracket Detail of Welded Bracket That Fits Against Steering Head

Upper Fairing Bracket Arm Weld Detail

Upper Fairing Bracket Arm Weld Detail

Upper Fairing Bracket Arm Weld Detail

Upper Fairing Bracket Arm Weld Detail

The headlight is still attached to the main wiring harness and I rest it on the front tire.

Headlight Hanging From Main Wiring Harness After Fairing Upper Bracket Removed

Headlight Hanging From Main Wiring Harness After Fairing Upper Bracket Removed

The middle fairing bracket is secured to the spine tube of the frame with a c;am shell clamp held by an Allan bolt. The clamp is between the two cables coming out of the front of the black timing chain cover. I make note of its location because I need to get it in the same location when I assemble the fairing to the panels will mount to the ends of the bracket.

Middle Fairing Bracket Location Between Two Wiring Cables from Black Timing Chain Cover

Middle Fairing Bracket Location Between Two Wiring Cables from Black Timing Chain Cover

Removing Middle Fairing Bracket Clam Shell Clamp

Removing Middle Fairing Bracket Clam Shell Clamp

Middle Fairing Bracket Mounting Bolt Detail

Middle Fairing Bracket Mounting Bolt Detail

The clamp is like a clam shell with a slot on one half and a tab on the other that fits into the slot.

Middle Fairing Bracket Clam Shell Bracket Detail

Middle Fairing Bracket Clam Shell Bracket Detail

Middle Fairing Bracket Clam Shell Half

Middle Fairing Bracket Left Clam Shell Half

Middle Fairing Bracket Clam Shell Halves

Middle Fairing Bracket Clam Shell Halves

Middle Fairing Bracket Clam Shell Assembly

Middle Fairing Bracket Clam Shell Assembly

I pull the bracket out on the left side. The bracket has a square nut welded on the other side that the Allan bolt screws into.

Middle Fairing Bracket Detail

Middle Fairing Bracket Detail

Middle Fairing Bracket Hardware Detail

Middle Fairing Bracket Hardware Detail

Middle Fairing Bracket Removed

Middle Fairing Bracket Removed

There are two lower fairing brackets mounted to the front engine mount.

Lower Fairing Bracket Attached to Front Engine Mount

Lower Fairing Bracket Attached to Front Engine Mount

I remove the engine mount bolts on each side and remove the two lower fairing mounts.

Removing Lower Side Panel Bracket with 19 mm Socket

Removing Lower Side Panel Bracket with 19 mm Socket

Lower Side Panel Bracket Detail

Lower Side Panel Bracket Detail

Lower Side Panel Bracket For Later Version of Lower Side Panels With a Split

Lower Side Panel Bracket For Later Version of Lower Side Panels With a Split

Remove Rear Fender Assembly

Next I remove the rear fender assembly that includes the license plate bracket with side reflectors, tail light housing, turn signals and stalk, the cowling tool box and the rear wiring sub-harness. You can read about how I do that here.

Remove Electrical Wiring and Components

Now I can remove most of the electrical components and then the main wiring harness and the various sub-harnesses that connect to it. You can see how I do this here.

Remove Front & Rear Brakes

I remove all the disk brake components (master cylinders, steel & rubber lines, calipers). I’ll remove the disk rotors after I remove the wheels and tires. You can see how I do this here.

Remove Center Stand

I remove the center stand at this point because I’m going to put the bike on my lift so it’s easier to remove the wheels and front suspension. You can leave the center stand on if you still want to use it while disassembling the bike.

The center stand on the 1983 R100RS has separate mounting tabs welded to the frame. The mounting hardware uses a countersunk Allan bolt with the head next to the oil pan and the locking nut on the outside.

Center Stand, Left Side Pivot Bolt Lock Nut

Center Stand, Left Side Pivot Bolt Lock Nut

Center Stand. Right Side Pivot Bolt Locking Nut

Center Stand. Right Side Pivot Bolt Locking Nut

There is not much clearance between the oil pan and the head of the countersunk Allan bolt. I can barely get my Allan wrench part way into the socket. If the bolt was rusted or tight, I wouldn’t have been able to remove it. What I need to do is cut down an Allan wrench to fit and add that to my special tools stash.

Remove Center Stand Pivot Bolt

Remove Center Stand Pivot Bolt

Remove Center Stand Pivot Bolt-Tight Fit for Allan Key

Remove Center Stand Pivot Bolt-Tight Fit for Allan Key

The head of the countersunk bolt interferes with the lip of the oil pan. I learned that the trick to getting it out is to remove the center stand springs and then the pivot bolt bushing. This will free up the pivot bolt in the hole so I can tilt it downward and slide it past the oil pan.

Center Stand Pivot Bolt Hits Oil Pan

Center Stand Pivot Bolt Hits Oil Pan

Center Stand Springs Are Easier To Remove With Stand Retracted

Center Stand Springs Are Easier To Remove With Stand Retracted

Remove Center Stand Spring

Remove Center Stand Spring

Pry Center Stand Bushing Out

Pry Center Stand Bushing Out

Center Stand Bushing

Center Stand Bushing

Center Stand Tab Boss Detail

Center Stand Tab Boss Detail

Center Stand Hardware Detail

Center Stand Hardware Detail

The bushings have grooves worn into them. I’ll replace the countersunk head bolts, lock nuts and bushings and the springs as they are high stress, wear items.

Center Stand Pivot Bushing Wear

Center Stand Pivot Bushing Wear

And the center stand legs are worn through. I’ll have patches welded onto them.

Center Stand Legs Are Worn Through

Center Stand Legs Are Worn Through

Remove “Repair Kit” Side Stand

The stock side stand has been replaced with a repair kit (part# 46 53 1 454 750).

Side Stand Repair Kit Components [SOURCE: MAX BMW]

Side Stand Repair Kit Components [SOURCE: MAX BMW]

This stand has failed. But, there is also a Brown’s side stand on this bike which is very convenient as it is not obscured by the fairing so it’s easy to see if it is retracted.

Brown's Side Stand-I'll Keep This One

Brown’s Side Stand-I’ll Keep This One

I removed the damaged repair kit side stand to get it out of the way. I won’t replace it with another repair kit as I’m going to use the Brown’s side stand. I’ll remove the Brown’s side stand after I get the engine out of the frame.

That said, here are some pictures showing how the the repair kit components are mounted and showing the damage. I suspect someone sat on the bike with the side stand down and bent the side stand yoke arm.

I remove the shackle with the two springs. That lets me remove the pivot bolt, the brass bushing, and the side stand.

Repair Kit Side Stand Spring Assembly

Repair Kit Side Stand Spring Assembly

Repair Kit Side Stand Spring Assembly

Repair Kit Side Stand Spring Assembly

Repair Kit Side Stand Spring Assembly

Repair Kit Side Stand Spring Assembly

Side Stand Yoke Arm is Bent

Side Stand Yoke Arm is Bent

Side Stand Yoke Arm Detail

Side Stand Yoke Arm Detail

Repair Kit Side Stand Bolt

Repair Kit Side Stand Bolt

Remove Steering Components

I remove the steering components which include the handlebar controls, the handlebars, the instrument cluster and the instrument cluster bracket, and the steering damper assembly. You can see how I do this here.

Remove Front Suspension Components

I remove the front suspension components which include the front wheel, the front fender, fork brace, fork lower sliders, fork tubes, steering stem and fork top plate. You can see how I do this here.

Remove Rear Wheel, Rear Drive, Shocks and Swing Arm

With the rear fender assembly removed, I can remove the rear wheel, rear drive, rear shocks and the swing arm. Since I use the rear wheel to immobilize the drive shaft when removing the four bolts that secure it to the transmission output coupling, I leave the rear wheel on while I remove the four drive shaft coupling bolts. Then I remove only the right rear shock which is mounted to the rear drive using the left one to keep the swing arm level. After I remove the rear drive from the swing arm, I remove the left shock and then the swing arm. You can see how I do this here.

Remove Rear Sub-frame

With the swing arm removed, I can remove the rear sub-frame. The left-side grab handle for helping put the bike on the center stand is attached with the top left sub-frame bolt. There is a black plastic vanity cover over the bolt and it’s the same as the vanity cap used on the horn bolt head. The bolt is an Allan, countersunk style with the head on the inside of the sub-frame. This provides more clearance when removing the battery. I remove the cap and bolt.

Upper Left Sub-frame Nut Has A Vanity Cap

Upper Left Sub-frame Nut Has A Vanity Cap

Remove Upper Sub-frame Nut Vanity Cap

Remove Upper Left Sub-frame Nut Vanity Cap

Vanity Cap Detail

Vanity Cap Detail

Upper Sub-frame Countersunk Allan Bolt

Upper Sub-frame Countersunk Allan Bolt

Remove Upper Sub-frame Bolt

Remove Upper Sub-frame Bolt

Left Upper Sub-frame Mount Hardware Detail

Left Upper Sub-frame Mounting Hardware Detail

Left Upper Sub-frame Mount Hardware Detail

Left Upper Sub-frame Mounting Hardware Detail

The other bolt at the bottom leg of the sub-frame goes through the muffler mount on the frame. I remove it.

Lower Sub-frame Bolt

Lower Sub-frame Bolt

Lower Sub-frame Nut

Lower Sub-frame Nut

Remove Lower Rear Sub-frame Bolt

Remove Lower Rear Sub-frame Bolt

Lower Sub-frame Mount Hardware Detail

Lower Sub-frame Mounting Hardware Detail

Lower Sub-frame Mount Hardware Detail

Lower Sub-frame Mounting Hardware Detail

The right side of the sub-frame is mounted with the same hardware as the left and I remove it. Then I can slide the sub-frame to to the rear to remove it.

Removing Rear Sub-frame

Removing Rear Sub-frame

Rear Sub-frame Removed

Rear Sub-frame Removed

The other end of the grab handle is mounted with a bolt into the seat lock mechanism. I’ll remove it when I remove the seat lock.

Frame & Sub-frame Crack Inspection

With the sub-frame off, I can inspect the welds and the sub-frame for cracks. Often, the sub-frame welds crack or the tubes break. Also, the welds on the gussets at the rear of the frame can crack. It’s easy to repair these now prior having the powder coated.

The side covers are held in place with steel tabs welded to the support arms of the sub-frame. The tabs on the right side of this sub-frame are broken, so I will have to fabricate new ones and weld them on.

Sub-frame Side Cover Tab

Sub-frame Side Cover Tab

Sub-frame Broken Side Cover Tab

Sub-frame Broken Side Cover Tab

The seat hinge pins on the right top rail of the sub-frame can be cracked. Mine are rusty, but okay.

Sub-frame Rear Seat Hinge Pin

Sub-frame Rear Seat Hinge Pin

Sub-frame Front Seat Hinge Pin

Sub-frame Front Seat Hinge Pin

The pins for the tire pump can also get broken. Mine are okay.

Sub-frame Tire Pump Bracket

Sub-frame Tire Pump Bracket

Sub-frame Tire Pump Bracket & Side Gusset Weld

Sub-frame Tire Pump Bracket & Side Gusset Weld

The sub-frame cross-rail gusset welds can crack, but these are okay.

Sub-frame Cross-Brace Weld

Sub-frame Cross-Brace Weld

Sub-frame Cross-Brace Weld

Sub-frame Cross-Brace Weld

The rear frame lower cross-brace tube has a gusset that attaches to the muffler bracket and these crack. Mine are rusty, but otherwise okay. And the frame rear down tubes weld to the swing arm bushing and rear muffler bracket. These are okay.

Rear Frame Gusset Weld

Rear Frame Gusset Weld

Rear Frame Gusset Weld

Rear Frame Gusset Weld

Rear Frame Weld Down Tube Weld

Rear Frame Weld Down Tube Weld

Rear Frame Weld Down Tube Weld

Rear Frame Weld Down Tube Weld

The rear brake switch bracket is welded to the inside of the right muffler bracket and it has no problems.

Rear Brake Light Switch Bracket

Rear Brake Light Switch Bracket

So far, the sub-frame and welds on the rear of the main frame are in good condition.

Here is what the bike looks like now.

Bike After Sub-frame Removed

Bike After Sub-frame Removed

Remove Carburetors & Air Box

These are straight forward to remove. I show how to do that here:

Remove Exhaust System

This bike has a Brown side stand. Installation of this side stand slightly changes where the left side header pipe bracket is mounted. Normally the bracket is mounted on the rear engine mount stud. With the Brown side stand, it is mounted on the front of the Brown side stand bracket. Here is how I remove the exhaust system.

Remove Transmission

To remove the transmission, I first remove the clutch throw-out lever and the foot shift mechanism. Then I remove the transmission and the clutch throw-out rod. You can read about how to do this here.

Remove Engine Top End

To make it easier to remove the engine from the frame, I remove the top end. You can see how I do that here.

I shot a short video showing the procedure which is quite straight forward.

VIDEO: 1983 BMW R100RS Remove Engine Top End

Remove Engine From Frame

I am now ready to remove the engine from the frame. I need to remove the oil filter housing which I left connected when I removed the oil cooler as part of the fairing removal, and the front and rear engine mount studs.

Remove Oil Filter Cover

I remove the three Allan bolts that secure the cover.

Oil Filter Cover

Oil Filter Cover

Oil Filter Cover Mounting Hardware Detail

Oil Filter Cover Mounting Hardware Detail

Oil Filter Cover Removed

Oil Filter Cover Removed

Under the oil filter cover is a large, white o-ring and two metal shims. In the cover is a black, square profile o-ring.

WARNING:
See below for more details on the shims. The number of shims I show is specific to this engine and the depth of it’s oil filter canister. You may need a different number of shims.

Oil Filter Cover White "$2000" O-ring

Oil Filter Cover White “$2000” O-ring

Oil Filter Cover Shims-The Number is Specific To The Depth of This Bikes Oil Filter Canister

Oil Filter Cover Shims-The Number is Specific To The Depth of This Bikes Oil Filter Canister

Oil Filter Cover "Square" Seal

Oil Filter Cover “Square” Seal

Oil Filter Cover Component Detail

Oil Filter Cover Component Detail

The shims are critical to sealing the oil filter housing so oil is delivered within the engine. You can read more about how to decide how many shims to use here.

I pull out the oil filter and then check the oil filter pressure relief valve to be sure the screw is seated and the slot in the screw aligns with the slots in the oil filter housing.

Using A Magnet to Pull Oil Filter Out of Canister

Using A Magnet to Pull Oil Filter Out of Canister

Oil Filter Pressure Relief Valve Screw Inspection-Looks Fine

Oil Filter Pressure Relief Valve Screw Inspection-Looks Fine

Remove Engine Mount Studs

I removed the foot pegs earlier. Now I remove the rear engine mount stud. There are two spacers between the engine and the frame and a large spacer in the middle. The stud slides out easily.

Rear Engine Mount Studs and Middle Insert Detail

Rear Engine Mount Studs and Middle Insert Detail

Rear Engine Mount Stud-Left Spacer Detail

Rear Engine Mount Stud-Left Spacer Detail

Rear Engine Mount Stud-Right Spacer Detail

Rear Engine Mount Stud-Right Spacer Detail

Removing Rear Engine Mount Stud

Removing Rear Engine Mount Stud

 

Rear Engine Mount Stud Detail

Rear Engine Mount Stud Detail

I remove the nuts and washers securing the front stud and slide it out using a wrench on side and a socket on the other. At this point, the frame drops down onto the board under the oil pan.

Front Engine Mount Stud with Side Stand Bracket Beside It

Front Engine Mount Stud with Side Stand Bracket Beside It

Remove Front Engine Mount Stud

Remove Front Engine Mount Stud

Remove Front Engine Mount Stud

Remove Front Engine Mount Stud

Engine Mount Stud Hardware Detail

Engine Mount Stud Hardware Detail

Remove Front Engine Mount Stud

Remove Front Engine Mount Stud

There are two spacers between the frame and engine block. These are the same dimensions as the ones used on the rear engine mount stud. And, the two studs are the same length, 12 -1/16 inches (306 mm).

Front Engine Mount Stud Spacer Detail

Front Engine Mount Stud Spacer Detail

Engine Mount Stud Spacer Detail

Engine Mount Stud Spacer Detail

Engine Mount Stud Spacer Detail

Engine Mount Stud Spacer Detail

Engine Mount Stud Spacer Detail

Engine Mount Stud Spacer Detail

Engine Mount Studs Are Same Length, 12-1/16 inches (306 mm)

Engine Mount Studs Are Same Length, 12-1/16 inches (306 mm)

Remove Engine

I find the engine wants to tilt forward when not connected to the frame, so I secure it with a strap around the rear of the engine, but not the frame, and under the arms of the portable motorcycle lift to stabilize it. Then I shift the frame forward so the engine is up against the rear cross-brace of the frame.

NOTE:
In this description, “left” and “right” refer to the sides of the bike when you are riding it, which is the rule, not to the side of the bike seen in the photos when facing the front of the bike.

Stabilizing Engine with Strap While Orienting Frame Prior to Engine Removal

Stabilizing Engine with Strap While Orienting Frame Prior to Engine Removal

Then I tilt the frame to the left so the spine tube is on the left side of the top engine cover and there is a clear path upward for the engine.

Frame Orientation Prior to Removing Engine

Frame Orientation Prior to Removing Engine

In this orientation, I can bend down on the right side of the frame, remove the strap while balancing the engine. Then I use my legs to pick up the engine. As I lift it, I tilt the engine to the right and lift it out of the frame. Then I put it down on the floor.

Engine Out of the Frame

Engine Out of the Frame

Then I strapped the engine to the portable lift for now.

Engine Removed & Secured to Portable Motorcycle Lift

Engine Removed & Secured to Portable Motorcycle Lift

Frame

Frame

At this point, the bike is disassembled. Here is most of it except for the fairing and fenders that are at the painter.

An Airhead "Boxer" in Boxes :-)

An Airhead “Boxer” in Boxes 🙂

Remove Fork and Seat Locks

I remove the fork lock from the frame and the seat lock mechanism from the sub-frame. I need to remove them before having them powder coated. You can read how I do that here.

2 thoughts on “00 BMW 1983 R100RS Disassembly Down To The Frame

    • Hi Saunders,

      I hope it proves useful on your project. Best of success on keeping another airhead on the road. 🙂

      Best.
      Brook.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.