c.1952 Sunbeam-Porsche 990cc Special Registration no. XML 841 Frame no. S8-5250 Engine no. P-22034
A unique motorcycle. Beautifully engineered Offered to market for the first time
The manufacturing rights to the famous Sunbeam motorcycles were acquired by BSA Ltd in 1943 from AMC of London who had succeeded John Marston Ltd, manufacturers of Sunbeam's since 1887. AMC continued production with variations on Marston's range, even retaining the model designations however, BSA abandoned Sunbeam motorcycle production throughout WW2, producing only Sunbeam bicycles.
In 1945, BSA were given designs of German motorcycles as part of the reparations programme, basing the BSA Bantam and the Sunbeam S7 around those of the DKW R125 and the BMW R75 respectively. The running-gear of the first S7's were closely based on BMW lines, though the engine, a pre-war-designed in-line twin, was perhaps an unfortunate choice, lacking the power to match the S7's appearance. BSA themselves experimented with a four-cylinder version though this remained a prototype only.
In 1969, Gordon Griffiths the then owner of 'XML 841' became dissatisfied with the S8's lack of power, deciding to change its powerplant. Griffiths, a highly experienced motorcycle 'special' builder chose to transplant the S8's engine with that of a Volkswagen 1200 Beetle, but whilst as reliable as expected, the lack of power continued to fall short of the enthusiastic riders expectations.
Griffith's next step to increase the Sunbeam's power was a logical one, utilising a 1955 Porsche 'A-Series' motor. A special bell-housing was cast in aluminium, as were rocker-box covers, replacing the Porsche pressed-steel items. The Sunbeam-Porsche's first show outing was to the 1972 BMF Rally.
Road-tested by the late John Ebbrell for Motor-Cycle News (copy article on file) 'XML' made many show-stopping appearances including one at Olympia for 'Motor Cycle', having been fitted with concentric Amal carburettors as part of the owners continued commitment to improve the machine. A BMW tank and indicators, Norton 'Roadholder' forks and much-revised rear suspension have been fitted, the most recent modification being a custom-built Boyer-Bransden two-tier electronic ignition system and a genuine Vincent Black Shadow speedometer. The latter were acquired by 'XML's' second custodian, an APMC member and engineer, who inherited the machine in 1992 and is relinquishing it only because of increasing age.
This unique Sunbeam-Porsche is offered with an immensely-detailed history file, casting patterns, large-format photographs, V5C and RF60 logbook. A unique opportunity for the lover of motorcycle engineering at its best, or for the Porsche owner who relishes two wheels.