| MODEL | BMW R 47 1927 - 1928 |
| Year | 1927 - 1928 |
| Engine Type | Four stroke, two cylinder horizontally opposed boxer, pushrod operated OHV |
| Displacement / Capacity | 494 cc / 30.1 cu in |
| Bore X Stroke | 68 x 68 mm |
| Compression Ratio | 5.8:1 |
| Cooling System | Air cooled |
| Max Power | 13.2 kW / 18 hp @ 4000 rpm |
| Max Torque | — |
| Ignition | Bosch magneto |
| Induction | 1 x BMW Spezial 2-slide carburettor |
| Start System | Kick |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 3 Speed, hand change |
| Clutch | Single plate, dry, cable operated |
| Final Drive | Shaft |
| CHASSIS SPECS | |
| Frame | Twin loop steel tubular frame |
| Front Suspension | Leaf spring, 5 leaves |
| Rear Suspension | Rigid, sprung saddle |
| Front Brakes | 150 mm drum |
| Rear Brakes | External shoe brake on the drive shaft |
| DIMENSION SPECS | |
| Overall Length | 2100 mm / 82.7 in |
| Overall Width | 800 mm / 31.5 in |
| Overall Height | 950 mm / 37.4 in |
| Seat Height | 700 mm / 27.6 in |
| Wheelbase | 1410 mm / 55.5 in |
| Ground Clearance | — |
| Dry Weight | 116 kg / 256 lbs |
| Wet Weight | 130 kg / 286 lbs |
| WHEEL SPECS | |
| Front Tyre | 27 x 3.5 low pressure or 26 x 3.0 high pressure |
| Rear Tyre | 27 x 3.5 low pressure or 26 x 3.0 high pressure |
| FUEL SYSTEM | |
| Fuel Capacity | 14 Litres / 3.7 US gal |
| Fuel Consumption | 3.0 L/100 km / 78 mpg US |
| Top Speed | 110 km/h / 68 mph |
Photo: Palauenc05, CC BY-SA 4.0, via Wikimedia Commons
Photo: Bergfalke2, CC BY-SA 3.0, via Wikimedia Commons
The R 47 took over from the costly R 37 as BMW's 500 cc sports model in 1927, putting a tuned overhead-valve twin into the chassis of the touring R 42. At a much lower price than the R 37 it sold in far greater numbers, and privateers raced it with success. It kept leaf-spring front suspension, a rigid rear end and a hand-change three-speed gearbox.
