The paper discusses the design of a racing motorcycle engine to compete in World Superbike racing. This class of motorcycle racing is based on production machines with four-stroke engines only. The rules allow three engine variants to be used, a 750 cm3 four-cylinder engine, a 1000 cm3 twin-cylinder engine, and a 900 cm3 three-cylinder engine. To date only the first two variations have been employed but this paper shows that the 900 cm3 engine has the highest potential power output of the set. This is demonstrated using engine simulation software and the finest detail of the design of the engine and its ducting are supplied within the discussion.The input data for the engine simulation is provided by empiricism so that the design is initially well-matched from the intake bellmouth to the end of the exhaust system. The outcome of this empirical process is confirmed by the engine simulation to be a relevant initial design procedure.