| MODEL | BMW R 45 1978 - 1979 |
| Year | 1978 - 1979 |
| Engine Type | Four stroke, two cylinder horizontally opposed boxer, pushrod operated, 2 valves per cylinder |
| Displacement / Capacity | 473 cc / 28.9 cu in |
| Bore X Stroke | 70 x 61.5 mm |
| Compression Ratio | 9.2:1 |
| Cooling System | Air cooled |
| Max Power | 20 kW / 27 hp @ 6500 rpm; 26 kW / 35 hp @ 7250 rpm |
| Max Torque | 37.5 Nm / 27.7 lb-ft @ 5000 rpm |
| Ignition | — |
| Induction | 2x Bing V65 constant velocity carburettors |
| Start System | Kick |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 5 Speed |
| Clutch | Single plate, dry |
| Final Drive | Shaft |
| CHASSIS SPECS | |
| Frame | Steel double loop frame |
| Front Suspension | Telescopic hydraulic fork, 175 mm / 6.9 in travel |
| Rear Suspension | Long swing arm with adjustable struts, 110 mm / 4.3 in travel |
| Front Brakes | Single 260 mm disc, 2 piston caliper |
| Rear Brakes | 200 mm drum |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | 1400 mm / 55.1 in |
| Ground Clearance | — |
| Dry Weight | 185 kg / 408 lbs |
| Wet Weight | 205 kg / 452 lbs |
| WHEEL SPECS | |
| Front Tyre | 3.25 - 18 |
| Rear Tyre | 4.00 - 18 |
| FUEL SYSTEM | |
| Fuel Capacity | 22 Litres / 5.8 US gal |
| Fuel Consumption | — |
| Top Speed | 145 km/h / 90 mph (27 hp); 160 km/h / 99 mph (35 hp) |
Launched at the 1978 IFMA alongside the R 65, the R 45 was BMW's new small boxer, with a short-stroke 473 cc twin in a compact double-loop frame styled under Hans Muth. It was sold in a 27 hp form that fell into a cheap German insurance class and a 35 hp version for other markets. The 27 hp bike became BMW's best seller and in 1979 Germany's best-selling motorcycle, though testers found it slow for a BMW.
