Road Racing World Championship Grand Prix is the premier championship of motorcycle road racing. It is currently divided into three classes: MotoGP, Moto2 and Moto3. All three classes use four-stroke engines. In 2010, 250 cc two-strokes were replaced by the new Moto2 600 cc four-stroke class. In 2012, 125 cc two-strokes were replaced by the Moto3 250 cc four-stroke class with a weight limit of 65 kg with fuel, and the engine capacity for MotoGP increased from 800 cc to 1,000 cc. Grand Prix motorcycles are purpose-built racing machines that are neither available for purchase by the general public nor can be ridden legally on public roads. This contrasts with the various production-based categories of racing, such as the Superbike World Championship, that feature modified versions of road-going motorcycles available to the public.