1962 Royal Enfield 173cc Overhead-Camshaft Prototype
Registration no. PSU 573
Frame no. 175-1
Engine no. 175-1
One thing seems certain; Enfields overhead cam prototype is a machine that will form the centre of attraction wherever it is parked. It seems a pity that such a promising British lightweight never went into production. If it had, there might have been another story to tell. Jeff Clew, The Classic Motor Cycle, December 1989.
Conceived during 1961 and designed by the firms Chief Draughtsman, Reg Thomas, Royal Enfields new lightweight model first appeared in 1962. The solitary prototype made (the machine offered here) was powered by a 173.5cc overhead-camshaft engine that represented a capacity class popular in Continental Europe and fell below the UKs 200cc limit that attracted preferential insurance rates. The single overhead camshaft was driven by chain, via a pair of pinions, from the crankshafts right-hand end, running inside a tunnel cast into the iron cylinder barrel, the latter topped by an alloy head. Looking not unlike the pushrod Crusader motor, at least as far as its top end was concerned, the cammy Enfield appeared very different below the waistline, where aluminium castings extending rearwards contrived to make it look not unlike the Aermacchi Chimera. A new frame was complemented by cycle parts taken from other Enfield models, while the gearbox was a five-speed Albion unit. At the time of the publication of Jeff Clews article (copy available), the Enfield Prototype was owned by Ken Blake, who had recently completed its restoration. The little Enfield was road tested by Jeff, who found that it possessed a peppy engine that thrived on revs, was pleasant to ride and handled well. Not run while in the current owners possession, this unique machine is offered with Swansea V5 registration document.
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