Ducati ST4s

ST4s

Manufacturer	Ducati
Production	2002-2005
Predecessor	ST2/ST4
Successor	ST3/ST3s
Class	Sport touring
Engine	L-twin, Fuel-Injected, 4 desmodromic valves per cylinder, liquid cooled
Power	86 kW (115 hp) @ 8,750 rpm
Torque	Template:Auto Nm @ 7,000 rpm
Transmission	6-speed
Wheelbase	Template:Auto mm
Seat height	Template:Auto mm
Weight	Template:Auto kg (dry)
Fuel capacity	21 L (4.6 imp gal; 5.5 US gal)

History: The ST series were Italian sport touring motorcycles made by Ducati between 1998 and 2007. This series began in 1998 with the ST2 and later in 2000 added the ST4. The difference between these two motorcycles was primarily their engines, with the ST2 having a 944cc Desmodue 2-valve motor, and the ST4 using the Super-Bike derived (from the previous series) Desmoquattro 916 4-valve motor. With the release of the 996 Desmoquattro Super-Bike 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 dropped, both being replaced by the ST3, using the 3-valve Desmotre engine which had a 992cc displacement. 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. Both the ST4s and ST3s could also be equipped with ABS, the first motorcycle in the Ducati line to have such an option. The ST3 and ST3s series were discontinued as of 2008 due to poor sales, and arguably, a lack of marketing by Ducati.

The ST4s was the pinnacle of performance for this line of motorcycles, and as of this writing, Ducati has no plans to follow this series with another motorcycle.

Technical: The Ducati ST4s used the liquid cooled Desmoquattro (four valve desmodromic valve) engine based on the Ducati 996. The Desmoquattro was largely unchanged from the 996 Super-Bike, and retained a valve angle of 40°. The chassis design was based on the ST4 but with the larger engine, and improved suspension. Otherwise it was a competent trellis framed sports tourer with a protective fairing, and optional colour matched luggage. An upgrade to the ST line in 2004 brought a trip computer, 4-way (hazard) flashers, digital speedometer and tachometer, a dashboard-controlled adjustable headlight, Euro-2 catalytic exhaust (except USA), and a simplified CAN-bus wiring setup.

The trip computer could calculate the following (2004 and later models only):

• Total trip distance
• Average speed
• Average fuel economy
• Instantaneous fuel economy
• Distance to empty

Specifications

• Bore x stroke: Template:Auto mm x Template:Auto mm.
• Compression ratio: 11.5:1.
• Power (measured at the rear wheel): 86 kW (115 hp) at 8,750 rpm.
• Torque: Template:Auto Nm at 7,000 rpm.
• Maximum engine speed (electronically limited): 10,500 rpm.
• Induction: Marelli electronic fuel-injection with two 50 mm throttle bodies.
• Ignition: Electronic, single centrally-positioned spark plug per cylinder.
• Starting: Electric.
• Clutch: Hydraulically actuated dry multiplate clutch (2005 ST4s used a wet clutch).
• Transmission: Six-speed gearbox with chain final drive.
  • Gear ratios: 1st 37:15, 2nd 30:17, 3rd 27:20, 4th 24:22, 5th 23:24, 6th 24:28.
  • Primary drive ratio: 1.84:1.
  • Final drive ratio: front sprocket 15T, rear sprocket 38T.
• Suspension:
  • Front: 43 mm Showa inverted cartridge forks, TiN-coated, adjustable for preload.
  • Rear: Öhlins monoshock adjustable for preload, compression and rebound damping.
    • ST4s-specific light-weight Aluminum swingarm.
    • 2002 and 2003 models had a factory-installed carbon-fibre rear mudguard. Other years used an ABS-plastic part.
• Wheels: Light-weight, forged Aluminum, Marchesini 5-spoke.
• Brakes:
  • Front: Twin 320 mm discs with Brembo four-pot opposed piston callipers.
  • Rear: Single 245 mm disc with Brembo twin-pot opposed piston calliper.
• Tyres:
  • Front: 120/70 ZR17 Michelin Pilot Sport tubeless.
  • Rear: 180/55 ZR17 Michelin Pilot Sport tubeless.