M900S4

Introduced for the 2001 model year, this was the first Monster to use Ducati’s liquid-cooled four-valve Desmoquattro architecture, bringing a more serious superbike-derived character to the naked-bike formula that had already made the Monster famous. Ducati positioned it as the high-performance step above the earlier air-cooled 900 models, pairing the familiar trellis-frame Monster concept with major mechanical and chassis updates that reflected the company’s sportier direction at the start of the 2000s. It marked an important evolution in the Monster family, showing that the stripped-back design could support substantially more performance without losing its distinctive urban, minimalist identity. The model remained in the range through the 2003 model year, after which it was succeeded by the S4R for 2004. Among enthusiasts, it is remembered as the original four-valve Monster and a key bridge between the early air-cooled Monsters and the more aggressive high-spec versions that followed.