00 BMW 1977 R100RS Planning the Build

Summary

This bike shows rather low mileage when I bought it, about 37,300 miles. However, modifications have been made including dual plugging the heads, a deeper oil pan, VDO oil pressure and temperature senders and gauges, heated grips, Telefix fork brace and the later snowflake wheels with the mandatory upgraded reinforced front wheel.

The engine is what is known as a “CFO”, which stands for “California, Florida, Oregon”. These engines had 38 mm exhaust instead of the standard 40 mm and different model Bing carburetors to meet state pollution requirements. The standard so called “Big Valve Heads” are installed on the CFO engines; the exhaust ports the headers connect to are sized at 38 mm instead of 40 mm, but the 44 mm inlet and 40 mm exhaust valves are the same as used on the Standard 1977 engine.

Rather than restoring the bike to original condition, my plan is to keep all the modifications that are still functional as they represent “in the day” upgrades to improve the performance and capabilities of the R100RS.

Although it’s a nice looking “10 foot” bike, there are numerous areas where work is required as shown in the “Inspection Pictures” below. The bike was well loved early in it’s life and then at some point neglected as evidenced by the rust and corrosion. The engine had a failure at some point as the original ALFIN cylinders and high compression pistons and rings were replaced with the later Nikasil cylinders with lower compression pistons and rings.

Inspection Pictures

"10 Foot" View

“10 Foot” View

"10 Foot" View

“10 Foot” View

"10 Foot" View

“10 Foot” View

10 Foot View

10 Foot View

The body work is in poor condition.

Screen Damage

Screen Damage

Fairing Panel Damage

Fairing Panel Damage

Fairing Panel Damage

Fairing Panel Damage

Fairing Panel Damage

Fairing Panel Damage

Fairing Panel Damage

Fairing Panel Damage

The gas tank has been replaced and it has a number of dents in it.

Not Original Tank

Not Original Tank

Dents in Tank

Dents in Tank

Inside Fairing

Inside Fairing Some Missing Fasteners

The cockpit plastic is in good condition. But the clock is missing, tachometer needle is broken (so there is likely damage to the tachometer internals) and the rubber dash has damage.

Missing Clock

Missing Clock

There is rust on the exhaust and axles, leaking push rod tube seals, corrosion on the aluminum, etc., all typical of a bike that was not kept inside it’s entire life.

Dual Plug Heads

Dual Plug Heads

Not Too Dirty

Not Too Dirty

Push Rod Tube Rubber Leaks

Push Rod Tube Rubber Leaks

RustyCross-over Pipe

RustyCross-over Pipe

Some Rust Pits in Exhaust Headers

Some Rust Pits in Exhaust Headers

Carburetors Aren't Leaking

Carburetors Aren’t Leaking

Rust On Underside of Mufflers

Rust On Underside of Mufflers

Fork Tube Seal Leaks

Fork Tube Seal Leaks

TeleFix Fork Brace

TeleFix Fork Brace

Blue Anodized ATE Caliper

Blue Anodized ATE Caliper

Rusty Axles

Rusty Axles

Corrosion on Snow Flake Wheels

Corrosion on Snow Flake Wheels

Disconnected Wiring for Heated Grips

Disconnected Wiring for Heated Grips

High Level Plan

Here is my high level build plan. The goal is to complete this work by September 1, 2017, one year after I started so I can ride the bike to Pennsylvania for an R100RS 40th anniversary gathering.

Body Work

  • Repair cracks in fairing panels
  • Replace badly cracked top center panel
  • Repair cracks in side covers
  • Repair gas tank dents
  • Repair seat cowl dents

Refinish, Paint

  • Paint and pinstripe-body panels, gas tank, fenders, side covers
  • Powder coat-frame, sub-frame, battery box, swing arm, control levers, front fork sliders, handlebar clamps, horn brackets, steering damper rack & pinon cover, center stand, hand rail, seat rail
  • Paint-starter motor and relay, handle bar perches, choke assembly, rear brake rod
  • Aluminum parts-remove corrosion and refinish
  • Wheels-remove corrosion and powder coat
  • Valve covers-refinish and repaint
  • Carburetors-rebuild, refinish
  • Front brake calipers-annodize (Blue) [Came out badly 🙁 ]
    – Repaint with Duplicolor Anodize Blue
  • Replace all decals, stickers and rondels

Inspect, Repair, Rebuild as Needed

  • Left side horn bracket-weld broken mount
  • Top fairing bracket-weld broken mount
  • Speedometer and tachometer-repair
  • Clock and Amp Meter-repair
  • Front brake master cylinder-rebuild
  • Front brake calipers-rebuild
  • Rear brake shoes-replace
  • Front caliper pads-replace
  • Alternator brushes and bushings-replace
  • Left handle bar perch-weld torn tab
  • Clutch rebuild
  • Transmission
    – Bearings-replace
    – Seals-replace
    – Output shaft and 5th gear-refurbish with hard chrome and hone
  • Heads
    – Exhaust valve seats-replace
    – Intake and exhaust valves-replace
    – Valve springs and keepers-replace
    – Mill valve cover ridge flat
    – Pitted cam followers-replace (2) with used
  • Cylinders
    – Machine and replate with Nikasil to match new pistons
    – High compression (9.5:1) pistons, rings, gudgeon pins and circlips compatible with Nikasil cylinders-replace
  • Connecting Rods
    – Recondition for correct center-to-center distance between big and little ends
    – Install and ream new little end gudgeon pin bushings
    – Replace connecting rod bearings and bolts

Replace

  • All rubber parts including front dash
  • Rubber brake lines with braided steel lines
  • Caliper steel brake lines with stainless steel
  • Windscreen and fasteners
  • Engine front and rear main seals
  • Oil pump cover o-ring
  • Cam shaft seal
  • Steering head bearings-replace
  • Swing arm bearings-replace
  • Wheel bearings-replace
  • Push rod tube seals
  • Head and valve cover gaskets
  • Control cables: Throttle, Clutch, Front Brake
  • Used white face clock
  • Rear shocks
  • Exhaust system-38 mm stainless steel
  • Front and rear axles with good used ones
  • Tires and tubes
  • Update fasteners to stainless steel

Electrical System

  • Wiring connections-clean, de-oxidize
  • Frayed wires and connections-repair and replace
  • Voltage regulator-replace
  • Starter relay-replace
  • Horn relay-replace

Upgrades

  • Replace Fork upper plate and steering stem nut with Toaster Tan components
  • Replace low compression Nikasil pistons (8.2:1) with European high compression pistons (9.5:1), rings and gudgeon pin.

Routine Maintenance

  • Oil and oil filter
  • Brake fluid
  • Gear lube in transmission, drive shaft and rear drive
  • Grease bearing; steering head, swing arm, wheel

Revisions

2017-05-06  Updated to reflect problems found and changes made to the plan.
2017-08-07  Updated to reflect changes.

 

8 thoughts on “00 BMW 1977 R100RS Planning the Build

  1. Wow very ambitious work list. It should look great when done. Interested to see what you encounter along the way especially anything particular and inherent to this vintage an model. Thanks for sharing

  2. Help… I’m almost finished restoring a 1983 R100RS with help from this website and your YouTube videos, so many thanks for all your time and effort, I’d have really struggled without your help. My problem is that on the left switch unit which houses the horn, indicators and Hi-Lo switch I also have a three stage switch for the lights, off, on and dipped, or at least thats what I thin k it is. This isn’t on any of the wiring diagrams I can find. It has three wires coming from it in addition to the 9 shown on normal diagrams, a Green, Grey and Green/Brown wire. Any ideas?????

    • Hi Tim,

      I looked at a wiring diagram that covers your bike.

      –> https://sites.google.com/site/bmwr1007t/_/rsrc/1472858749518/wiring-diagram/Wiring%20Diagram.JPG

      I also checked my 1983 R100RS. Other than the nine wires that go to the left electrical switches, there is a two wire bundle going to the clutch switch, but that is it.

      Is the switch the 3 wires go to a separate switch on the handlebar beside the one that is integrated into the left handlebar casting? If so, someone added a switch, perhaps to control another set of running lights? You didn’t say, but are the three wires in a separate bundle? If so, try to trace where they go to see if it gives you any clues about what they connect to.

      Note, green is fused power via the ignition, grey is parking light power (distributed via grey-black to front parking, rear tail light and clock) and there is no “green/brown” anywhere that I know of.

      I hope this helps.

      Best.
      Brook.

  3. Hello Brook, I’ve been enjoying reading about your 1977 RS rebuild. I also own a 1977 RS, still wearing the original silver/blue satin paint. I consider my bike to be a ’10 footer’ as well and it’s in need of a repaint. Who did you use to respray your bike? Are you happy with the results? It’s difficult to tell by the photos, but did you opt for a gloss finish or the original satin sheen?

    Thanks for the info!

    • Hi Frank,

      The painter is no longer in business having moved to Phoenix, AZ when his wife was transferred there. I specified matte clear coat and got gloss. I decided to just accept it rather than have it redone. Such are the compromises of a rebuild project that I did not intend to be a full-on restoration.

      Best.
      Brook.

  4. Thanks for your quick response, Brook. I know of a place in Phoenix, AZ (Second Street Scooters) that has done silver/blue RS paint jobs & pinstriping. They quoted me roughly $2500 – $3000 for a ‘satin’ finish respray…and that is if no bodywork is required. I must remove all the painted panels and ship them…so there will be a freight cost as well.

    My original 1977 RS paint was in fairly good condition until I placed a magnetic tank bag on the tank. Big mistake! I placed the bag on the bike during a one month long, climate controlled storage period. Absolutely no moisture would have gotten to the bike at any point. When I removed the tank bag after one month, to my surprise there were 8 oval shaped blemishes in the satin paint, matching the location of the bags 8 fabric covered magnets. Nothing I have tried, including wax, rubbing compound, etc. will remove the marks.
    The blemishes are completely smooth to the touch and actually show the pattern of the tank bag fabric. All I can figure is there must have been some sort of bizzare chemical reaction during the month long dry storage period. There was no direct contact between the magnets and the paint – the tank bag material separated the two surfaces.

    Any idea of what may be going on? I can email you pics of the tank blemishes if you are interested in seeing what I’m talking about. I would hate to see someone else with a nice silver/blue RS ruin their paint job.

    • Frank,

      Very curious. I have no idea what may have caused this. From what you describe, it sounds as if there was either a color transfer of some sort from the bag to the tank or some contaminant that discolors the clear coat.

      In doing a bit of Google searching on magnetic signs and car paint, I see a number of folks ended up with whitish discoloration where the magnets touched the paint. A suggestion is to take the tank to a good body shop and ask if they might be able to remove it. A company I thought did good work on one of my cars is Mahnke (http://www.mahnkeautobody.com/). They have a couple locations in the Denver area.

      A fellow who has a good reputation for motorcycle painting in the Denver area is Craig (Biff) Weber, 303-808-2762. You might connect Biff and see what you can learn about repainting the bike if the auto body shop can’t fix the problem. I’ve seen his work, which was good quality, but I’ve not hired him for any painting, so can’t provide more than this about him.

      I hope this helps.

      Best.
      Brook.

  5. Hey…thanks for the advice, Brook. I’ll check with both of your recommendations.

    Best regards,

    Frank

    PS: Don’t put a magnetic tank bag on your beautiful RS. Ha!

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