The Kawasaki Ninja 250SL (codenamed BX250), formerly called Ninja RR Mono in Indonesia (until November 2016, later changed to 250SL), is a motorcycle in the Ninja sport bike series from the Japanese manufacturer Kawasaki sold since 2014. The bike replaces the 2-stroke Ninja ZX-150RR (also called Ninja RR) that was produced from 1989 to 2016.^[2][3] It is powered by a 249 cc (15.2 cu in) single-cylinder engine from the KLX250 that produces a claimed 20.6 kW (27.6 hp; 28.0 PS) at 9,700 rpm and 22.6 N⋅m (16.7 lbf⋅ft) of torque at 8,200 rpm mated to a 6-speed constant-mesh transmission.^[1]

It is the first Ninja sport bike to have a four-stroke single-cylinder engine.^{[citation needed]}