In the late '60s, Japanese motors were showing up in Class C dirt track and short track events. Typically, the 250 class was home to single-cylinder motorcycles, but Yamaha was now coming out with some high revving 250cc twins. Leave it to American ingenuity and the old “I wonder if." This NOS DS7 unit has been fitted in a Champion frame. Champion-made frames were generic chrome-moly frame that was readily adaptable to most small engines. The small fiberglass tank was typical. This unit has a clever Hurst rear brake set-up controlled by the left-hand handlebar lever. Note the use of sheet metal screws to secure the tires to the rim.