1974 Yamaha YZ250B 250cc Motorcycle

Description

Yamaha’s first dirt bike, the DT-1 enduro, was introduced in 1968, proving the Japanese manufacturer was capable of mixing it with the best in the burgeoning off road market.  The DT-1 was ultimately developed into a successful racer by Southern Californian Don Jones for his sons Gary and Dewayne around a custom-made frame and modified engine with reed-valves, with Gary scoring back to back wins in the AMA 250 National Championships in 1971-1972.  Yamaha turned the Jones’ racer into production bike in 1973, the YZ250 using a chrome-moly frame, milled alloy forks and Thermal Phase twin shocks and set a new benchmark in the field.  The YZ250 was a virtual works replica – expensive, exotic and sold only to qualified buyers, the explosive power delivery too much for amateur riders to handle.  Costing twice the price of an equivalent MX250, less than 1,000 were sold in the US and buyers were required to submit a resume before being approved.  Based on the works racers, Yamaha introduced a monoshock version for 1974, dubbed the YZ250B, the revolutionary rear end designed by Belgian engineer Lucian Tilkens.  The monoshock design doubled the available suspension travel whilst significantly increasing chassis rigidity, kick starting a revolution in dirt bike design.  These classic Yamaha dirt bikes number amongst the most collectible of all early Japanese motocross machines today, particularly those surviving in original condition.