Technical Data
The /5 models are air-cooled, four-stroke, opposed-twin (boxer) engines with hemispherical combustion chambers. The engine is built around a one-piece tunnel crank-case. The camshaft is driven by a duplex chain and is located below the crankshaft (unlike the /2 series which had the gear-driven camshaft above the crank). This reversed arrangement improves ground clearance for the same center of gravity and assists lubrication of the camshaft. Valves are actuated by the camshaft through hardened followers, push rods, and rocker arms.
The 500 cc and 600 cc models are equipped with Bing slide-type carburetors with 26 mm throats. The R75/5 comes with 32 mm Bing CV (Constant Vacuum/constant depression) type carburetors. As in all BMW motorcycles at the time, the clutch is a single-disk dry clutch.
Final drive is by shaft, running from the transmission by universal joint to an oil bath within the right rear swing arm and connecting to a bevel gear and ring gear on the other end. Unlike the /2 models (with the exception of the 1969 R69US), the /5 models are equipped with telescopic front forks, 12-volt alternator and electrics, and standard tachometer and turn signals.
R 50/5 | R 60/5 | R 75/5 | |
---|---|---|---|
Bore | 67 mm (2.6 in) | 73.5 mm (2.89 in) | 82 mm (3.2 in) |
Stroke | 70.6 mm (2.78 in) | ||
Displacement | 498 cc (30.4 cu in) | 599 cc (36.6 cu in) | 749 cc (45.7 cu in) |
Power | 32 hp (24 kW) @ 6,800 rpm | 40 hp (30 kW) @ 6,600 rpm | 50 hp (37 kW) @ 6,400 rpm |
Torque | 29 ft·lbf (39 N·m) @ 5,000 rpm | 36 ft·lbf (49 N·m) @ 5,000 rpm | 43 ft·lbf (58 N·m) @ 5,000 rpm |
Top Speed | 87 mph (140 km/h) | 99 mph (159 km/h) | 109 mph (175 km/h) |
Curb Weight | 452 lb (205 kg) | 463 lb (210 kg) | 463 lb (210 kg) |
Gross Weight Rating | 881 lb (400 kg) | ||
Alternator | Bosch 12 V • 180 Watts | ||
Spark Plugs | Bosch W230T30 / Champion N7Y | ||
Fuel Tank | 4.7 US gal (18 l; 3.9 imp gal) or 6.3 US gal (24 l; 5.2 imp gal) | ||
Tires | 3.25x19 front • 4.00x18 rear | ||
Rims | 1.85x19 front • 1.85x18 rear |
Read more about this topic: BMW /5 Motorcycles
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