| MODEL | BMW R 39 1925 - 1927 |
| Year | 1925 - 1927 |
| Engine Type | Four stroke, single cylinder vertical, OHV |
| Displacement / Capacity | 247 cc / 15.1 cu in |
| Bore X Stroke | 68 x 68 mm |
| Compression Ratio | 6.0:1 |
| Cooling System | Air cooled |
| Max Power | 4.8 kW / 6.5 hp @ 4500 rpm |
| Max Torque | — |
| Ignition | Bosch magneto generator type G 1.8V/15W |
| Induction | 1x BMW Spezial 20 mm |
| Start System | Kick |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 3 Speed |
| Clutch | Single plate, dry |
| Final Drive | Shaft |
| CHASSIS SPECS | |
| Frame | Twin loop tubular frame |
| Front Suspension | Trailing link with leaf spring, 4 laminae |
| Rear Suspension | Rigid, spring loaded saddle |
| Front Brakes | 150 mm internal shoe drum |
| Rear Brakes | External shoe brake on the drive shaft |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | — |
| Ground Clearance | — |
| Dry Weight | — |
| Wet Weight | 110 kg / 242 lbs |
| WHEEL SPECS | |
| Front Tyre | 27 x 3.5 balloon or 26 x 3.0 high pressure |
| Rear Tyre | 27 x 3.5 balloon or 26 x 3.0 high pressure |
| FUEL SYSTEM | |
| Fuel Capacity | 10 Litres / 2.6 US gal |
| Fuel Consumption | 2.5 L/100 km |
| Top Speed | 100 km/h / 62 mph |
The R 39 was BMW's first single-cylinder motorcycle, introduced in 1925 as a cheaper alternative to the costly R 32 twin. Its 247 cc overhead-valve engine sat upright in a tubular frame with shaft drive, and it was quick for its size: Josef Stelzer won the 1925 German road championship on one. Sales were modest, with 855 built.
