1934 NSU 500OSL
The little world of the motorcycle
created its own European community long before the politicians had the same
idea. So it was that NSU, a pioneer of the German industry achieved fame on the
racing circuits in 1930 with a single overhead camshaft engine developed by
Walter Moore, the English engineer who had just created the famous inter models
for Norton - and their German successors bore a strong family resemblance. In
1933, NSU profited from the experience gained form competition by introducing
the OSL 250, 350, 500, and 600cc which, apart from their overhead valve heads,
were replicas of the overhead cam racers.
Built to Last
German
built quality is legendary; all the components of the OSL were designed for
long service without problems. The chain was protected by chaincases, the
crankshaft turned in three bearings and the overhead valves where enclosed in
an aluminum casing atop the twin port cast iron head.
Exposed Valve
Springs
Only the massive hairpin valve springs were exposed to air -
and these were rapidly replaced by coil springs with an ingenious means of
taking the valve clearances by eccentrics accessible from the exterior. To
emphasize the relationship with the racing NSU "Bullus", the pushrods were
enclosed in a tube designed to look like racing overhead camshaft housing. The
touring aspect resided in the enclosed chaincase lubricated by oil mist from
the engine.