The Ducati 400SS was a sports motorcycle released alongside its smaller 350SS and larger 600SS siblings. The smaller 350SS was manufactured between 1991 and 1993, the 400SS was made from 1989 to 1997, and the larger 600SS from 1993 to 1999.
The 300SS and 400SS models were made to meet Japan's 400cc and Italy's 350cc regulations limits of the maximum displacements allowed for probationary motorcyclists. The 1994 Ducati 600SS was introduced as a cheap way to expand Ducati's range.
In 1990, the Italian motorcycle manufacturer launched the Ducati 400SS, a sports machine in its second year of production, featuring the same technical, visual, and performance specifications as the previous model without any modifications or improvements.
Visually, the 1990 machine was identical to the 1989 model, packing standard features, like a full fairing with a small windscreen and a steel trellis frame poking out, a rectangular headlight, a single seat, a single exhaust system with a muffler mounted on the left side, and three-spoke lightweight aluminum wheels.
The bike's steel trellis frame offered mounting points for a 41 mm Marzocchi inverted fork on the front and a Marzocchi preload and rebound-adjustable shock on the rear, acting as a suspension system.
As for power, the 1990 Ducati 400SS had installed a 398cc four-stroke air-cooled V-twin engine underneath its fairing. The engine was managed by a Mikuni carburetor, delivering an output power of 42 hp with maximum strength at 7,000 rpm and 35 Nm (26 lb-ft) torque at 8,500 rpm.