Ducati ST series

ST4s

Ducati ST4
Manufacturer	Ducati
Production	1997-2007
Class	Sport touring
Engine	L-twin

The Ducati ST series is a set of Italian sport touring motorcycles manufactured by Ducati between 1997 and 2007. Intended to compete with other sport-tourers such as the Honda VFR, the ST Ducatis featured a full fairing, a large dual seal, and a relaxed seating position for both rider and pillion. The ST bikes could be fitted with optional matching luggage.

In order of release, the models comprised the ST2, ST4/ST4s, and ST3/ST3s. Each model was outwardly similar, sharing the same frame, bodywork and cycle parts, but each model had a different engine, albeit all V-twins. The numeral after "ST" (2, 3 or 4) indicates the number of valves per cylinder. In the Ducati tradition, the frame was a tubular steel trellis item, and the conventional suspension comprised USD forks and a rear monoshock. The ST series later had a facelift, getting an updated nose and headlight.

Design and development

Ducati ST4s

This series began in 1997 with the ST2 in Europe before Ducati shipped the model to the United States in 1998. Ducati added the ST4 model in 1999. The ST was partially a replacement for the Paso, but also represented a more serious entry by Ducati into the burgeoning Sport Touring market. The difference between the ST2 and the ST4 was primarily their engines, with the ST2 having a 944 cc Desmodue two-valve motor, and the ST4 using the four-valve Desmoquattro motor derived from the previous series 916 superbike. Other differences were in the construction of the frame and electrical systems, and also the choice of suspension component manufacturers.

With the release of the 996 Desmoquattro superbike in 1999, the 916 engine was slowly phased out of production, last seen in the 2003 ST4. In late 2001, to upgrade the ST line, the 996 Desmoquattro was added to the ST, along with other specific enhanced suspension components, giving rise to the ST4s, which appeared first as a 2002 model.

In 2004, the ST2 and ST4 were phased-out, both being replaced by the ST3, using the three-valve Desmotre engine which had a 992 cc displacement. However, the ST4s was continued, and remained as the top model in the line.

In 2006, the ST4s production was discontinued in favor of an ST3s variant, inheriting the suspension components of the ST4s but keeping the Desmotre motor unchanged from the normal ST3. The reasons given for the ST4s' demise are that the ST3 motor required less maintenance and would also meet Euro-3 emissions levels, where the 996 motor (in its then-current design) would not pass the more stringent emissions standard, and also required more expensive maintenance.

The ST3 and ST3s, and consequently the ST series, were discontinued as of 2008 having only sold 1,011 total worldwide units in 2007. Arguably, a loss of interest in this market segment by Ducati and subsequent refocusing of the brand, coupled with the model's low sales and Ducati's recurring financial troubles, sealed the ST's fate. Ducati confirmed again, in its factory plan for 2008–2010, that sport touring was eliminated as a model segment.