ESSAY: THOSE DAMN CRANK GEARS Our Technical Editor recalls the shortcuts Yamaha made with its fabled two-stroke TZ750A engine.

When Yamaha designed its TZ750A engine more than 40 years ago, certain shortcuts were necessary to get it into production quickly. To avoid the problem of making a pressed-together crankshaft four cylinders wide, they built that engine with two separate 180-degree twin cranks that were closely...