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.
The body work is in poor condition.
The gas tank has been replaced and it has a number of dents in it.
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.
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.
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.
- Repair cracks in fairing panels
- Replace badly cracked top center panel
- Repair cracks in side covers
- Repair gas tank dents
- Repair seat cowl dents
- 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
– Output shaft and 5th gear-refurbish with hard chrome and hone
– 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
– 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
- 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
- Wiring connections-clean, de-oxidize
- Frayed wires and connections-repair and replace
- Voltage regulator-replace
- Starter relay-replace
- Horn relay-replace
- 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.
- Oil and oil filter
- Brake fluid
- Gear lube in transmission, drive shaft and rear drive
- Grease bearing; steering head, swing arm, wheel
2017-05-06 Updated to reflect problems found and changes made to the plan.
2017-08-07 Updated to reflect changes.