Lot details
Registration No: Un-Reg
Frame No: 549019
Engine No: AS8441
cc: 500

1954 saw the introduction of what has come to be regarded by many as the definitive racing BMW motorcycle, the R54 Rennsport offered as a production racer for a lucky few privateers and raced as a factory machine, which provided the basis for all subsequent BMW racing motorcycles.
The new machine was fitted with a horizontally opposed double overhead cam engine with dimensions of 66 x 72 mm giving a displacement of 492cc, although later on the engine changed to square 68 x 68 mm dimensions and the works did run machines with a 70 x 64 mm bore and stroke at times.The cams were operated by bevel driven shafts and ran on needle roller bearings. The valves were set at a fairly wide 82 degree included angle in the part-spherical heads and were controlled by duplex coil springs. The carburettors, initially Fischer-Amal TT types replaced by Dell 'Orto SS1 instruments later on the production version, were mounted with a 15 degree downdraught angle. The works machines did, on occasion employ a Bosch fuel injection system. The crank, ran in three main bearings and was housed in a one piece, cast, electron crankcase. The conrods were of an unusual flat section and were crowned by forged pistons manufactured by Mahle. The cylinders were cast in aluminium and either had shrunk in liner or a chrome plated bore and featured modest finning thanks to their uninterrupted location in the airflow. Six studs secured them to the crankcase. A flywheel clutch controlled the drive to the all indirect four speed gearbox with drive being taken from there to the rear wheel via a drive shaft encased in the right hand fork of the swinging arm which was controlled by two hydraulic damper/spring units.. The front of the crankcases housed a gearcase which provided drive to the oil pump and magneto. The engine and gearbox were housed in a twin loop cradle type frame, attaching to the frame via three mounting points. The front suspension was either of the Earles type, as fitted to the machine offered, or telescopic forks. A 200mm twin leading shoe brake equipped the front end and a single leading shoe item graced the rear, although a hydraulic drum brake, as fitted here, was employed at different times by the works riders.
The example offered is one of only twenty four production racers manufactured by BMW and was originally raced with success by the German rider Alois Huber, well known in the UK having participated in a number of TT's and later by Ernst Hiller and Lothar John. When new it was equipped with the 66 x 72 mm long stroke engine producing 48 bhp, however this was replaced during the 1960s by the later, more powerful factory short stroke engine with the 70 x 64 mm bore and stroke. The machine, which is in excellent condition, has always been serviced by Dieter Busch whilst in the vendors ownership and is reputed to be the most powerful and fastest BMW RS extant.

PLEASE NOTE: This motorcycle is a BMW RS54 and not as described in the catalogue.