Did the Two-Stroke Have to Die?

Did the two-stroke have to die? Well, yes. Even back in the early days of Honda, Soichiro's business partner Takeo Fujisawa declared their two-stroke street machines were 'dirty and smelly'.

Two-strokers were great because they were simpler than four-strokes and produced two power strokes for every one in a four-stroke, making it about twice as powerful for the same cubic capacity. The trouble is, bad things belch out of them. Uncharacteristically setting the environmental precedent, America banned two-strokes way back in 1984. Things is, when the piston is on its down-stroke to eject exhaust gases, it also ingest the new mixture, some of which is punted straight through the exhaust port and into the air completely unburned. This became a big problem in the environmentally friendly Nineties.
Then came the potential saviour of two-strokes: the Bimota V-due, a 500cc V-twin descended from Bimota's halted 500cc GP project. Bimota's way of doing the two-stroke thing differently was by separating the air/fuel mix, with air introduced as before but fuel directly injected on to the hot piston crown.

This would only happen when the compression stroke had sealed both inlet and exhaust ports, meaning that all the fuel got burned economically. Nice, eh? Er, no. It was released way too early and, by the time the fuel glitch problems were sorted, no-one cared and Bimota fell to its knees.

The kiss of death for two-strokes finally came at the end of 2002, when the final works 500cc V4 two-strokes were ushered off the MotoGP grid forever into the crusher...