In the 1980s, manufacturers had imposed (voluntarily in most countries) a performance limit. The arbitrary figure of 125 bhp was adapted to meet the growing criticism that the bikes were too fast for street use. The ‘80s also saw the gradual demise of the 2-stroke as more stringent emission laws were introduced in most countries to offset the effects of global warming. The Yamaha RZ500 V4 shown above was loosely based on the factory TZ racers, as was the RG 500 Suzuki.

These four cylinder 2-strokes, water cooled machines were every bit as sophisticated as their Grand Prix cousins.