BSA MC1 250 Racer

Alan Cathcart wonders what might have been had BSA followed through and raced its unusual twin cam MC1 250cc single.


The MC1 250cc single, created by BSA in the 1950s, seemed to have a genuine chance of fulfilling the dream of a Made in England World Championship.

Photo By Kyoichi Nakamura

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1954 BSA MC1
Claimed power:
34hp @ 10,250rpm (at gearbox sprocket)
Top speed: 105mph
Engine: 248.5cc air-cooled DOHC horizontal single-cylinder with bevel-gear camshaft drive, four radial valves and external flywheel, 70mm x 64.5mm bore and stroke, 10.1:1 compression ratio
Weight (dry): 248lb (113kg)
Fuel capacity/MPG: 7gal (26.5ltr)

The roll call of would-be British world beaters — bikes that would lead to a Made in England World Championship glory by following in the title-winning tire tracks of the Manx Norton and AJS Porcupine — is long, but scarcely illustrious.

All too often, hopes for success crumbled into dust when a bike turned out to be misconceived or critically deficient in some crucial aspect. Machines like the Read-Weslake 500 twin, the KRM Superstreak 350 Four or the Roberts V5 MotoGP racer (made with Yankee money, but conceived and built in England), to name just three, inspired dreams of victory that transpired to be cruel mirages. But among such abortive projects, the MC1 250cc single created by BSA in the 1950s, then the world’s largest motorcycle manufacturer, seemed to have a genuine chance of fulfilling the dream.

MC1 beginnings

In the immediate post-World War II era, Bert Hopwood, then an engineer at Norton, created the legendary Dominator parallel twin. In May 1948, Hopwood became chief engineer at BSA. Eager to develop an innovative, new generation of products for BSA, in 1949 he roughed out the concept of a 250cc single — simply coded MC1 — with a horizontal cylinder and four radial valves operated by short, chain-driven, overhead camshafts connected by bevel gears. At a time when long-stroke engines were the accepted norm, the MC1’s square 68mm x 68mm dimensions were unusual. Hopwood’s assistant at Norton, Doug Hele, followed him to BSA in 1949, and in 1950 was commissioned by Hopwood to put this concept into metal as the prototype for a family of road bikes, with a possible view to racing in the Lightweight TT in the Isle of Man where Moto Guzzi singles of comparable format were dominant. MC 

Order the November/December 2012 issue of Motorcycle Classics to read more about the BSA MC1 250 Racer. Contact Customer Service at (800) 880-7567 or contact us by email.