The history and future of two-stroke engines

While supporters of two-stroke engines emphasize their advantages, naysayers have for years been predicting the death of the little engine that could.

For motorcycles powered by two-stroke engines, 1969 was the best of times and the worst of times. The best because Kawasaki unveiled the Mach III, a three-cylinder, two-stroke, 500-cm³ screamer that redefined what high-performance motorcycles were expected to do. The worst because Honda introduced the CB 750K, a four-cylinder, four-stroke, 750-cm³ model. The CB 750K was the first in a long line of what the motorcycle press dubbed the UJM-the Universal Japanese Motorcycle. Within a decade, four-strokes ruled the motorcycle kingdom and two-strokes had become relics.

The Mach III and its 750-cm³ cousin, the Mach IV (introduced in 1972), epitomized two-stroke performance. They were light, inexpensive, and frighteningly fast (made even scarier by their marginal handling). They were also noisy, smelly, fuel thirsty, and were prone to engine failure. Although the motorcycling public would have accepted the bikes' shortcomings in exchange for their performance, the EPA could not overlook their exhaust emissions.