WANKEL IN THE ISLAND

To use a rotary or Wankel engine in an off-road motorcycle isn’t a recent thing and in fact Hercules fielded a three-rider team mounted on such machines in the 1975 ISDT. It was an evaluation exercise and the bikes were their converted roadsters with riders of proven experience mounted on them, just not the then-current top factory team men. According to Motorcycle’s report on these Wankels, the attempt was both a success and a failure as none of the bikes finished the gruelling event though not because of mechanical problems.

In the ISDT there are various capacity classes with a variety of speed schedules in place and this was the root of the problem as there was and still is some dispute over the actual measurement of a Wankel’s capacity. Hercules and engine maker Sachs reckoned their bikes were 294cc, the ISDT committee and FIM regulations said “… no, they measure 588cc…” which put the bikes in a completely different speed class and they just weren’t fast enough to keep up. Motorcycle got a chance to try one for an hour or so and found the Wankel to be an interesting ride on the dirt and not something for a novice as the power came in like a switch which had Motorcycle’s man pulling unintentional wheelies at every twist of the throttle. Such things can be sorted by development and the reporter said at the end of his review that once Sachs and Hercules tamed the top end and gave the bottom end a bit of tractability, the bike could be a serious contender.