or more cylinders, although Honda made the 'almost' V8 oval-piston NR750 road bike and NR500 GP bike, having eight connecting rods. Morbidelli has shown two V8 prototype road bikes that were not produced. Other types Wankel rotary Wankel engines produce high power outputs for their size and weight, and several attempts were made to produce Wankel powered motorcycles in the 1970s. Yamaha and Kawasaki exhibited Wankel-powered motorcycles in 1972, but neither company manufactured one. German manufacturer Hercules, a member of the Sachs-controlled Zweirad Union, produced their single-rotor W2000 from 1974 to 1977. Suzuki produced their single-rotor RE5 from 1975 to 1976. Van Veen built 38 OCR1000 motorcycles with twin-rotor Comotor engines between 1978 and 1981. BSA experimented with Wankel engines before they ended production in the 1970s. These experiments later led to Wankel-engined Norton motorcycles in the 1980s and 1990s, including the Classic, the Commander, the fleet-only Interpol 2, and the F1. Steve Hislop won the 1992 Senior TT on a Wankel-powered Norton. Curved Cylinder The four-stroke crank-rocker engine with a curve cylinder was also invented to study its efficiency. The novel design of that engine reduced the number of parts and was expected to enhance the overall efficiency. Oval pistons Honda NR Rotary engines Megola, Killinger and Freund Motorcycle Turbine engines MTT Turbine Superbike (turboshaft) Jet Reaction afterburning turbojet Other jet engine motorcycle prototypes exist, but never have been commercialized. Rocket Several rocket-powered motorcycles have been built, including: Fritz von Opel's 1928 "Monster" rocket bike Skycycle X-2 rocket developed for Evel Knievel's Snake River Canyon jump attempt Eric Teboul's rocket-powered dragbike that set the world record at Santa Pod Raceway in 2009 Electric Diesel Only very small numbers of diesel engined motorcycles have ever been built. The improved fuel efficiency is offset by the increased weight, reduced acceleration and potential difficulty of starting, at least in colder climates. Enfield India built a few from 1965 onwards but is no longer doing so. In November 2006, the Dutch company E.V.A. Products BV Holland announced their first diesel-powered motorcycle, its Track T-800CDI, using an 800 cc three-cylinder Daimler Chrysler diesel engine. Several armies are moving to an all-diesel engine fleet to reduce the fire risks of gasoline and the need to provide two different fuels. This includes their dispatch riders as well, encouraging the market for diesel motorcycles. Interest in biofuels is also likely to encourage future developments for small Diesels.