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 A 1952 R51/3 – note the half-width brakes before 1954 | |
| Manufacturer | BMW |
|---|---|
| Production | 1951-5 |
| Engine | 494cc four-stroke flat-twin |
| Bore /stroke | 68 mm × 68 mm (2.68 in × 2.68 in) |
| Compression ratio | 6.3:1 |
| Top speed | 140 km/h |
| Power | 24 hp |
| Ignition type | Magneto |
| Transmission | Single-plate dry clutch, 4-Speed manual |
| Suspension | Front telescopic forks, rear plunger |
| Brakes | 200mm drums |
| Wheelbase | 1400mm |
| Dimensions | L: 2130mm W: 790mm H: 985mm |
| Weight | 190 kg (wet) |
| Fuel capacity | 17 L |
| Oil capacity | 2 L |
| Fuel consumption | 4.5L/100KM |
TheBMW R51/3 wasBMW's second post-World War II 500 ccmotorcycle, following the briefly produced R51/2. It featured aflat-twin engine and exposeddrive shaft.[1] In 1951, the R51/3 succeeded and modernized the 1950 R51/2, which was essentially a pre-war design that was produced after the war. The 600 cc R67, R67/2, and R67/3 series and the more sportingR68 model also followed the R51/2.
Following World War II, Germany was precluded from producing motorcycles of any sort by the Allies. When the ban was lifted, in Allied-controlled Western Germany, BMW had to start from scratch. There were no plans, blueprints, or schematic drawings. Company engineers had to use surviving pre-war motorcycles to create new plans. In 1948, it introduced the 250 cc R24, which was essentially a pre-war R23, complete with rigid rear end.
When larger machines were permitted,BMW introduced its R51/2 in 1950, a model that was in production for only one year and that was essentially a pre-war BMW produced after the war. The R51/3 was then introduced in 1951 for a production run of four years.
The 600 cc R67, sister model to the R51/3 and almost identical visually, was also introduced in 1951, but it went through two revisions. The more powerful R67/2 came out one year later and was replaced in 1955 by the R67/3, which was in production through the 1956 model year.
In 1952, BMW introduced the 600 cc R68,[2] which produced 35 hp (26 kW), had a compression ratio of 8.0:1.
| R51/3 | R67 – R67/3 | |
|---|---|---|
| Design | BoxerFlat Twin | |
| Engine | Four-strokeOHV | |
| Model Years | 1951–1955 | 1951–1956 |
| Bore | 68 mm / 2.68 in | 72 mm / 2.83 in |
| Stroke | 68 mm / 2.68 in | 73 mm / 2.87 in |
| Displacement | 494 cc (30.1 cu in) | 594 cc (36.2 cu in) |
| Power | 24 hp (18 kW) @ 5800 rpm | 26 hp (19 kW) / 28 hp (21 kW) @ 5500 rpm |
| Compression Ratio | 6.3:1 | 5.6:1 / 6.5:1 |
| Top Speed | 140 km/h (87 mph) | 150 km/h (93 mph) |
| Curb Weight | 190 kg (419 lb) | |
| Gross Vehicle Weight | 355 kg (783 lb) | |
| Fuel Tank Capacity | 17 L (3.7 imp gal; 4.5 US gal) | |
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