JohnGoFast
It's definitely the two-stroke motor developed by Dieter König and used very successfully in sidecar racing. It was also used for solo GPs by an Aussie John Dodds and Kim Newcombe.
Kim Newcombe used the König to take second place in the 1973 500 GP season. Two different teams used it to win the sidecar championships in 1974, '75 and '76.
A very interesting development in two-stroke history, it's main problems were caused by clutch and gearbox issues.
Crazy