Motorworld’s newspaper №46
The first step to the ideal was the model R37 – a powerful bike, but too expensive for the average buyer. German engineers found a way out – reducing production costs by simplifying the design.
Letter from BMW confirming the production date of the motorcycle (March 03, 1928) and the date when it was shipped to a dealer in Danzig (April 25, 1928).
BMW engineers had taken 500 cc OHV engine from R37 as a base, added simplified frame and suspension, and got rid of all electricals that were not a must. AAs a result, they were able to lower the motorcycle cost by 36% while keeping all of the bike’s racing ambitions thanks to the engine.
R47 flat-twin OHV engine was the same as the one used on the touring model R42, except its rating increased to 18 h.p. and the maximum speed increased to 110 km/h. BMW sold 1720 R47 motorcycles – ten times more than R37! Most of the R47 motorcycles were sold to German racing clubs.
The main reason for the R47 success was that BMW did not present the new model as a racing-only motorcycle. The model had been offering in a “bare” version, but the client could choose from many options, e.g. generator, horn, and headlight. A fuel tank of larger capacity was also offered as an option. With a larger tank, R47 might be a part of the «Gran Turismo» class.
Model R47 occupies a place of honor among BMW motorcycles because it was truly advanced for its time. For example, roller bearers were used for the first time (in the design of the valve rocket arm), replaceable bushings, and an innovative control system (except for manual shifting).
|Manufacturer||Bayerische Motoren Werke, AG (Germany)|
|Years of manufacture||1927-1928|
|Quantity produced, units||1 720|
|Price||1 850 RM|
|Today’s value||5373,81 $|
|ENGINE AND TRANSMISSION|
|Engine capacity, cc||494|
|Bore and stroke, mm||68 х 68|
|Engine rating||18 h.p. at 4000 rpm.|
|Carburetor||BMW Spezial 22 mm|
|FRAME AND WHEELBASE|
|Frame type||Duplex tubular|
|Front suspession||Leaf spring, 5 plates|
|Brakes||Front – drum-type, rear– foot brakes (on cardan shaft)|
|Wheel size||3.00х26 when using high-pressure tyres, 3.50х27 when using low-pressure tyres|
|Ground clearance, mm||
|Gas tank size, l||
|Maximum speed, km/h||