Sunday, February 04, 2007
The evocative sepia photo shows Graham Browne racing his '25 TT Douglas at Brooklands. The color photo shows the same bike at Brooklands, where it now lives, in original condition, after being left to the museum by Mr Browne himself, who retained ownership throughout his life. A remarkable partnership, by any standard.
The bike is very interesting, as it has a cast aluminum sump beneath the engine, and a proper oil pump circulating the oil under pressure. Only the pukka works racing Douggies had this feature; otherwise the bike looks fairly standard compared to, say, my own prosaic machines! A look at the engine close-up reveals the fins of the sump beneath the engine, and an oil pressure gauge on top of the airbox (another unique feature of the Douglas, added by Freddie Dixon). The oil pump proper is visible at the center of the sump; it's driven by a shaft-and- bevel arrangement inside the airbox.
The induction manifolds are wrapped with friction tape to keep them from freezing up when alcohol fuel is used. The engine never gets particularly warm when using alcohol, as it burns much cooler than gasoline. If the manifolds freeze, the carbs can freeze as well and jam the throttle wide open during a race - exciting but best avoided. I experienced manifold frost on the BMW R63 mentioned in an earlier post; the pipes were almost a foot long, and gained a haze of moisture as on a cold drink, almost immediately after starting the engine.