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1981 BMW R 100RS Overview
BMW R 100RS is a classic motorcycle, displacing 980 cc. Power comes from a Two cylinder boxer, four-stroke engine running OHV valve actuation, a compression ratio of 9.5:1. On the performance side, it delivers 51 kW @ 7000 rpm of peak power and 76 Nm @ 6000 rpm of torque. Top speed is factory-quoted at 196 km/h. On the road, the 1981 R 100RS tips the scales at 230 kg, carries a 24-litre fuel tank, offers a seat height of 820 mm and spans a 1465 mm wheelbase. That's roughly 34 kg heavier than the average classic motorcycle in our database. The full 1981 BMW R 100RS spec sheet below covers every technical detail, from suspension travel to tyre sizes.
1981 BMW R 100RS compared with other bikes in the Classic category
We checked the recorded figures for the 1981 BMW R 100RS against up to 909 bikes in the Classic category in our database, counting each model once at the model year nearest to this one.
- Only 67 of the other 591 bikes in the Classic category have a higher power output than the 51 kW of the R 100RS.
- With 980 cc, the R 100RS has the joint 108th largest engine displacement of 909 bikes in the Classic category, 90% above the category average of 516 cc.
- Top speed of 196 km/h is higher than that of 375 of the other 437 bikes in the Classic category.
- Narrowing the field to the 102 models within five model years of it, the power output of 51 kW is higher than that of 91 of the other 101.
Versus the 1979 model
The figures we track are unchanged from the 1979 model: peak power, peak torque, wet weight, displacement, seat height and top speed all match.
1981 R 100RS - Pros & Cons
Strengths
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⚡
Strong power output: With 51 kW @ 7000 rpm and 76 Nm @ 6000 rpm of torque on tap, the R 100RS is no slouch for its class.
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Strong front braking: Stopping power up front is strong thanks to the disc setup, with plenty of room to upgrade further with braided lines.
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Large fuel range: A 24-litre tank means fewer stops on longer rides - a genuine plus for touring or a lengthy daily commute.
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Low-maintenance final drive: Running a shaft final drive cuts out the regular chain cleaning and tensioning that most bikes need.
Considerations
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🔧
Carburetor fuelling: Expect to spend more time keeping the carbs in tune, especially after long storage periods or a change in altitude.
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Drum rear brake: Rear braking comes from a drum, not a disc - it does the job but won't match the feel or fade resistance of newer equivalents.
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Tall seat height: At 820 mm, shorter riders will likely be on tiptoes at a standstill - worth sitting on one before you buy.
Wear Points & Servicing Notes
Heat management in traffic
Because the R 100RS relies on airflow rather than a coolant jacket, expect noticeably more radiant heat at low speed and in traffic. It's inherent to air cooling, and ventilated gear largely offsets it.
Carburetor maintenance
Carburetors on the R 100RS need periodic attention - pilot jets and float needles are the first parts to gum up after the bike sits, and the first thing to check if idle or throttle response degrades.
Brake disc and pad wear
Braking up front comes from 2 x Ø260mm discs, 2 piston calipers - solid stopping power, with disc and pad wear best checked on the same schedule as tyre changes.
Suspension condition on used examples
The R 100RS's suspension runs Telescopic fork with hydraulic shock absorber at the front. The rear uses Long swinging arm with adjustable strut. Fork-seal condition and rear linkage play are the two things worth checking before buying used.
Final drive maintenance
The R 100RS uses shaft final drive: essentially maintenance-free day to day, with periodic gear-oil changes the only real service item.
Frame & chassis check
Built around a Double sown tubs, dual cradle, the R 100RS's chassis is straightforward to inspect: look for corrosion, cracks or repair welds around stress points like the head-stock and swingarm mounts.
Handling the weight at a standstill
230 kg puts the R 100RS toward the heavier end of its class. It's most noticeable at walking pace; once underway the mass settles into the handling rather than fighting it.
R 100RS - Buying & Maintenance Guide
What to check before buying
Before handing over money for a used 1981 BMW R 100RS with its 980 cc classic, cover the fundamentals: service book and oil change history, drivetrain wear, and any sign of oil weeping around the casings. This model runs shaft final drive, so ask for proof the shaft-drive gear oil has been changed on schedule - it's easy to overlook since there's no chain to draw attention to it. Now 45 years old, this classic is as likely to show age-related wear (perished rubber, seized fasteners, degraded seals) as mileage-related wear. Cold-starting it yourself tells you a lot - a healthy R 100RS should catch quickly and settle into a smooth idle.
Oil and filter changes
Nothing protects the R 100RS's 980 cc two cylinder boxer, four-stroke like disciplined oil changes - stay on the manufacturer's schedule (roughly every 6,000 km or annually). With a 9.5:1 compression ratio, running the octane grade specified in the manual matters more than on a lower-compression engine. Match the viscosity grade to what the owner's manual specifies, not what's cheapest.
Carburetor upkeep
Deposits in the carbs are the usual culprit behind poor running on a stored R 100RS - strip and clean the float bowls before the first start. Pilot jets clog first and get overlooked most, so make a point of checking them.
1981 BMW R 100RS - Frequently Asked Questions
What engine does the 1981 BMW R 100RS have?
The 1981 BMW R 100RS uses a Two cylinder boxer, four-stroke engine with 980 cc of displacement. It is air cooled.
What is the top speed of the 1981 BMW R 100RS?
The 1981 BMW R 100RS has a factory-quoted top speed of 196 km/h. Real-world speeds vary depending on rider weight, conditions and state of tune.
How much does the 1981 BMW R 100RS weigh?
The 1981 BMW R 100RS weighs 230 kg. This is the manufacturer's wet figure.
How much power does the 1981 BMW R 100RS make?
The 1981 BMW R 100RS produces 51 kW @ 7000 rpm of power and 76 Nm @ 6000 rpm of torque. These are peak figures.
What is the fuel tank capacity of the 1981 BMW R 100RS?
The 1981 BMW R 100RS has a 24-litre fuel tank. At around 5-6 litres per 100 km, that is roughly 400-480 km between stops.
Is the 1981 BMW R 100RS suitable for shorter riders?
The 1981 BMW R 100RS has a seat height of 820 mm. This is towards the tall end of the spectrum and will require most riders under 175 cm to tiptoe at stops.
What brakes does the 1981 BMW R 100RS have?
The 1981 BMW R 100RS uses 2 x Ø260mm discs, 2 piston calipers at the front and Simplex ∅200 mm drum at the rear.
What tyre sizes does the 1981 BMW R 100RS use?
The 1981 BMW R 100RS runs 3.25 - H19 front and 4 - H18 rear tyres. A good selection of sport, touring and all-weather rubber is available in these sizes.
What gearbox does the 1981 BMW R 100RS have?
The 1981 BMW R 100RS is fitted with a 5 Speed transmission.
BMW R 100RS Spec Evolution
The BMW R 100RS was produced across 9 model years (1976-1989). The table below highlights the key specifications that changed across the production run - useful whether you are comparing years or tracking down a specific variant.
| Specification |
1976 |
1977 |
1979 |
1981 |
1983 |
1985 |
1987 |
1988 |
1989 |
| Max Power |
51 kW / 70 hp / @ 7000 rpm |
51 kW / 70 hp / @ 7000 rpm |
51 kW / 70 hp / @ 7000 rpm |
51 kW / 70 hp / @ 7000 rpm |
51 kW / 70 hp / @ 7000 rpm |
51 kW / 70 hp / @ 7000 rpm |
- |
- |
43.8 kW / 59.5 hp @ 6500 rpm |
| Wet Weight |
230 kg / 506 lbs |
230 kg / 506 lbs |
230 kg / 506 lbs |
247.0 kg / 544.5 lbs |
230 kg / 506 lbs |
230 kg / 506 lbs |
243.0 kg / 535.7 lbs |
243.0 kg / 535.7 lbs |
243.0 kg / 535.7 lbs |
| Engine Type |
- |
- |
- |
Air-Cooled Boxer Twin |
Two cylinder boxer |
Air-Cooled Boxer Twin |
Two cylinder boxer |
Two cylinder boxer |
Two cylinder boxer |
| Top Speed |
196 km/h / 121.5 mph |
196 km/h / 121.5 mph |
196 km/h / 121.5 mph |
196 km/h / 121.5 mph |
196 km/h / 121.5 mph |
196 km/h / 121.5 mph |
186.0 km/h / 115.6 mph |
186.0 km/h / 115.6 mph |
186.0 km/h / 115.6 mph |
| Fuel Capacity |
24 Litres / 6.3 US gal |
24 Litres / 6.3 US gal |
24 Litres / 6.3 US gal |
24 Litres / 6.3 US gal |
24.00 litres / 6.34 gallons |
24 Litres / 6.3 US gal |
22.00 litres / 5.81 gallons |
22.00 litres / 5.81 gallons |
22 Litres / 5.8 gal |
| Displacement (cc) |
- |
- |
- |
980 cc |
979.00 cc |
980 cc |
979.00 cc |
979.00 cc |
979.00 cc |
| Displacement (ci) |
- |
- |
- |
59.8 cu-in |
59.74 cubic inches |
59.8 cu-in |
59.74 cubic inches |
59.74 cubic inches |
59.74 cubic inches |
| Fuel Control |
- |
- |
- |
OHV Pushrod 2-Valve |
OHV |
OHV Pushrod 2-Valve |
OHV |
OHV |
OHV |
Key Specifications
Engine
Two cylinder boxer, four-stroke
Power
51 kW / 70 hp / @ 7000 rpm
Torque
76 Nm / 7.75 kgf-m / 56 ft-lb @ 6000 rpm
Top Speed
196 km/h / 121.5 mph
Fuel Capacity
24 Litres / 6.3 US gal
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Full 1981 BMW R 100RS Specifications
Year
1980 - 81
Make
BMW
Model
R 100RS
Make Model
BMW R 100RS
Seat Height
820 mm / 32.3 in
Wheelbase
1465 mm / 57.67 in
Ground Clearance
165 mm / 6.49 in
Height
1300 mm / 51.8 in
Length
2130 mm / 83.8 in
Width
746 mm / 29.37 in
Dry Weight (lbs.)
210 kg / 463 lbs
Fuel Capacity
24 Litres / 6.3 US gal
Wet Weight
230 kg / 506 lbs
Engine Type
Two cylinder boxer, four-stroke
Fuel Control
OHV
Stroke
70.6 mm
Displacement (cc)
980 cc
Displacement (ci)
59.8 cu-in
Engine Type
Air-Cooled Boxer Twin
Fuel Control
OHV Pushrod 2-Valve
Displacement
980 cc / 59.8 cub in.
Engine Detail
Four stroke, two cylinder horizontally opposed Boxer, 2 valves per cylinder
Bore x Stroke
94 x 70.6 mm
Compression Ratio
9.5:1
Cooling System
Air cooled
Fuel Consumption
4.8 L/100 km / 20.8 km/l / 49 US mpg
Fuel Induction
2 x Constant depression carburettors, Bing 94/40/105 - 94/40/106
Ignition
Battery ignition
Lubrication
Wet sump
Starter
Electric
Valve System
2
Clutch
Dry single plate, with diaphragm spring
Final Drive
Shaft
Final Drive Gear Ratio (Bevel/Crown Teeth)
11/32 teeth or 10/32 teeth
Gear Ratios
1st 3.38 / 2nd 2.43 / 3rd 1.93 / 4th 1.67 / 5th 1.50
Gearbox
5-speed
Transmission / Drive
5 Speed
Frame Type
Double sown tubs, dual cradle
Suspension - Front
Telescopic fork with hydraulic shock absorber.
Suspension - Rear
Long swinging arm with adjustable strut.
Wheel Travel - Front
200 mm / 7.8 in
Wheel Travel - Rear
125 mm / 4.9 in
Alternator
Bosch 12V/240 W
Brakes - Front Diameter (mm)
260 mm
Brakes - Front Diameter (in.)
10.2 in
Brakes - Rear Diameter (mm)
200 mm
Brakes - Rear Diameter (in.)
7.9 in
Brakes - Front
2 x Ø260mm discs, 2 piston calipers
Brakes - Rear
Simplex ∅200 mm drum
Tyres - Front
3.25 - H19
Tyres - Rear
4.00 - H18
Wheel Ratio - Rear
1:2.91 or 1:3.00
Wheels - Front
2.15 - B19
Wheels - Rear
2.50 - B18
Specifications are compiled from manufacturer documentation and cross-referenced
technical sources, and corrected on an ongoing basis.
Spot an error? Let us know.
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