| MODEL | BMW R 61 1938 - 1941 |
| Year | 1938 - 1941 |
| Engine Type | Four-stroke, air-cooled, horizontally opposed twin (boxer), side-valve, 2 valves per cylinder |
| Displacement / Capacity | 600 cc / 36.6 cu in |
| Bore X Stroke | 70 x 78 mm |
| Compression Ratio | 5.7:1 |
| Cooling System | Air cooled |
| Max Power | 13.4 kW / 18 hp @ 4800 rpm |
| Max Torque | — |
| Ignition | Battery ignition |
| Induction | 1 x Amal M75/426 S carburettor |
| Start System | Kick |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 4-speed (combined hand/foot shift optional) |
| Clutch | Single dry plate |
| Final Drive | Shaft |
| CHASSIS SPECS | |
| Frame | Twin-loop steel tubular frame |
| Front Suspension | Telescopic fork |
| Rear Suspension | Plunger suspension |
| Front Brakes | 200 mm drum |
| Rear Brakes | — |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | — |
| Ground Clearance | — |
| Dry Weight | — |
| Wet Weight | 184 kg / 405 lbs |
| WHEEL SPECS | |
| Front Tyre | 3.00 - 19 |
| Rear Tyre | 3.50 - 19 |
| FUEL SYSTEM | |
| Fuel Capacity | 14 Litres / 3.7 US gal |
| Fuel Consumption | — |
| Top Speed | 115 km/h / 71 mph |
Photo: Yesterdays Antique Motorcycles, CC BY-SA 4.0, via Wikimedia Commons
Photo: Yesterday Antique Motorcycles, CC BY-SA 4.0, via Wikimedia Commons
Introduced in 1938 as the entry-level twin of BMW's new range, the R 61 replaced the R 6 and kept its 18 hp side-valve 600 cc engine. Its big step forward was plunger rear suspension, developed from BMW's Six Days trial bikes, combined with a telescopic front fork. A docile, torquey machine often used with a sidecar, it was built until 1941, with 3,747 made.
