1929 BMW 486cc R52
Frame no. 26735
Engine no. 49935
After only a few years BMW updated its original R32 tourer, which in 1926 became the R42, gaining a redesigned and more powerful engine boasting detachable alloy cylinder heads and cooling fins set at 90 degrees to the cylinder axis. The engine was set further back in the duplex loop frame, which improved weight distribution and enabled straight front down-tubes to be used. The braking too came in for attention: the old block-and-pulley type rear brake being replaced by a drum on the driveshaft gripped by external contracting bands. Electric lighting was still regarded as an 'extra' and would not be standardised until 1928.
That same year BMW revised its range of engines and added a brace of 750s, adopting a long (78mm) stroke for the sidevalve tourers and short (68mm) stroke for the sporting overhead-valve models. Thus the sidevalve-engined R52 employed bore/stroke dimensions of 63x78mm for a capacity of 486cc and in addition featured the newly redesigned gearbox, common to all models, which incorporated a side-throw kickstart and direct gearchange, the lever now being mounted on the 'box rather than the engine. BMW motorcycles evolved quickly throughout the 1920s and the range in this form lasted only until the end of 1929 when a switch to pressed-steel frames was made. As a result, the R52 was produced for barely two years and today this rare BMW is among the marque's most desirable and sought after machines of the Vintage period.
This particular R52 was purchased from a jointly owned Spanish private collection in 2007 and comes with Spanish registration papers. In addition, there are documents on file relating to Swiss ownership in the 1940s/1950s. The machine features a Bosch horn and OTA '120km/h' speedometer.