BMW R 45 (1978-81) vs BMW R 39 (1925-27)
Comparison technical specifications
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| Make: | BMW | BMW |
| Model: | R 45 | R 39 |
| Years: | 1978-81 | 1925-27 |
| Engine: | Four stroke, two cylinder horizontally opposed Boxer, pushrod operated 2 valves per cylinder. | Four stroke, single cylinder vertical, OHV |
| Capacity: | 453 cc / 27.6 cu in. | 247 cc / 15.1 cu in. |
| Compression Ratio: | 9.2:1 | 6.0:1 |
| Cooling System: | Air cooled | Air cooled |
| Induction: | 2 x Bing V65 carburetors | 1 x BMW Spezial ∅20 mm |
| Ignition: | Bosch contact free electronic ignition | Bosch magneto generator type G 1.8V/15W |
| Starting: | Kick | Kick |
| Max Power: | 20 kW / 27 hp @ 7250 rpm | 4.8 kW / 6.5 hp @ 4000 rpm |
| Transmission: | 5 Speed | 3 Speed |
| Final Drive: | Shaft | Shaft |
| Front Suspension: | Telescopic hydraulic forks | Plate spring, 4 laminae |
| Rear Suspension: | Long swinging arm with adjustable strut | Rigid, spring loaded saddle |
| Front Brakes: | 2 x ∅260mm Disc, 2 piston caliper. | Internal shoe drum brake ∅150 mm / ∅5.90 in diameter |
| Rear Brakes: | Single ∅200mm drum | External shoe brake at the gearing on Cardan shaft |
| Front Tyre: | 1.85 - B18 | 27 x 3.5" balloon or with 26 x 3.0" high pressure tyres |
| Rear Tyre: | 2.50 - B18 | 27 x 3.5" balloon or with 26 x 3.0" high pressure tyres |
| Fuel Capacity: | 22 L / 5.8 US gal | 10 liters / 2.6 US gal |