Friday, 1 March 2013
At last! A 'Mystery bike' that Stuart didn't guess!
It's a Polish built Sokół 1000 from the 30s.
In late 1927 the Polish Army created a specification for a general purpose heavy motorcycle that was to replace the Harley-Davidson motorcycles used by then. By 1932 the Centralne Warsztaty Samochodowe works prepared a short series of roughly 200 CWS M55 motorcycles equipped with a sidecar. Although heavily-based on American designs (the bike itself was based upon Harley-Davidson, while the engine was almost a direct copy of Indian), the machine proved to be unreliable.
Because of that in 1931 it was decided to prepare a completely new heavy motorcycle for the Polish Army. Subsidized by the state, the PZInż holding extensively tested and modified the earlier M55 design to fit the specifications. Initially named CWS M III, the new construction was to be reliable and immune to harsh conditions, bad service and user-friendly. Because of that, the final motorcycle was slightly outdated and particularly heavy, even as for its class. However, it proved to be extremely reliable and durable. However, the quality had its price and the bike was sold in civilian version for 4,200 złoty, that is roughly US$800 or UK£170, a price only slightly lower than that of an average car of the epoch.
The production started in 1933 and lasted until the outbreak of World War II in 1939. Mass produced entirely in Poland (less than 5% of parts were imported), Sokół 1000 maintained the high quality throughout the production period. Every tenth motorcycle was delivered extensively checked for parameters and all machines were road-trialed before delivery.
Its durability proved to be a major advantage and Sokół 1000 was much faster off-road than many of the previously-used American counterparts. Among the most notable innovations introduced in the Polish construction was a soft sidecar mounting, which allowed for easier handling and greater off-road speed.
Sokół 1000 was also the basis for Sokół M121 trike prototype, with the sidecar wheel powered. Its engine was also used for railway draisines.
So Stuart nearly got it right. The Harley influence is clear from the frame, and that engine is a near copy of an Indian, it even has the foot operated clutch.
I assume this is the 'soft sidecar mount' mentioned above.