Ducati ST4s

The ST series were Italian sport touring motorcycles made by Ducati between 1998 and 2007. The models included (in order of release) the ST2, ST4, ST4s, ST3, ST3s.

ST4s

2002 Ducati ST4s
Manufacturer	Ducati
Production	2002-2005
Predecessor	ST2/ST4
Successor	ST3/ST3s
Class	Sport touring
Engine	996cc 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 (2002-2003), Template:Auto kg (2004-2005) (dry)
Fuel capacity	21 L (4.6 imp gal; 5.5 US gal)

History

This series began in 1998 with the ST2 and later in 2000 added the ST4. 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 944cc Desmodue 2-valve motor, and the ST4 using the Super-Bike derived (from the previous series) Desmoquattro 916 4-valve motor. 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 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. 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 frequent and expensive maintenance.

The ST3 and ST3s, and consequently the ST series, were discontinued as of 2008 having only sold 1,011 total world-wide 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.

Technical

The Ducati ST4s used the liquid-cooled Desmoquattro (four desmodromic valves) engine based on the Ducati 996. The Desmoquattro was largely unchanged from the 996 Super-Bike, and retained a valve angle of 40°. However, the ST4s actually made slightly more power and torque than the 996 Super-Bike due to the mostly straight-through design of the ST's exhaust, compared to the under-seat exhaust of the Super-Bike.

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 standard colour matched luggage (luggage was optional on other ST series models). The ST came equipped with a center-stand, an accessory power outlet, and both the ST4s and ST3s could also be equipped with ABS, the first motorcycle in the Ducati line to have such an option.

In 2004, an upgrade to the ST line brought a slightly redesigned nose fairing and dashboard, adjustable ergonomics, a trip computer, 4-way (hazard) flashers, digital speedometer and tachometer, a dashboard-controlled adjustable headlight, a new seat design, Euro-2 catalytic exhaust (except USA - Euro-3 was achieved in the 2006 ST3), and a simplified CAN-bus wiring setup. The refinements also shaved 11 kilograms from the weight of the motorcycle due to the lighter wiring harness and simpler support structure for the nose of the motorcycle.

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

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

In 2004 and 2005, Ducati added wet clutches to many models, including the ST series in 2005. This reduced the force necessary to engage the clutch, and rider fatigue, which was a welcome change for heavy traffic where clutch engagement may be frequent. However, Ducati purists were less than pleased with the removal of the signature dry clutches. This is due to the wet assembly's reduction of the sound level of the clutch, sounds which are very pleasing to some riders. As well, aftermarket clutches including popular racing "slipper" assembles, were not possible to install without special parts that few dealers carried.

Later, Ducati partially remedied this situation by making APTC (Adler Power Torque-Plate Clutch, a back-torque limiting device, like a "slipper" clutch) standard on most models that received the wet assembly. Unfortunately, the ST series never received this upgrade.

Specifications

Engine

• Bore x stroke: Template:Auto mm x Template:Auto mm.
• Compression ratio: 11.5:1.
• Power (Ducati measured at the front sprocket until 2005, later at the crankshaft, however the engine remained unchanged):
  • 2002-2004: 86 kW (115 hp) at 8,750 rpm.
  • 2005 only: 89.1 kW (119 hp) at 8,750 rpm.
• Torque:
  • 2002-2004: Template:Auto Nm at 7,000 rpm.
  • 2005 only: Template:Auto Nm at 7,250 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 with anti-theft immobilizer, using a chip embedded in the key.

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.
• Clutch:
  • 2002-2004: Hydraulically actuated dry multiplate clutch.
  • 2005 only: Hydraulically actuated wet multiplate clutch.
• Top speed: Template:Auto km/h.

2002 Ducati ST4s showing suspension components

Chassis

• Wheelbase: Template:Auto mm.
• Seat height: Template:Auto mm.
• Weight (dry):
  • 2002-2003: Template:Auto kg.
  • 2004-2005: Template:Auto kg.
• Suspension:
  • Front: 43 mm Showa inverted cartridge forks, TiN-coated, adjustable for preload.
    • Rake: 24°
  • Rear: Öhlins monoshock adjustable for preload, compression and rebound damping.
    • ST4s-specific light-weight boxed Aluminum swingarm.
    • 2002 and 2003 models had a factory-installed carbon-fibre rear mudguard. Other years used an ABS-plastic part.

Wheels and tyres

• Wheels: Light-weight, forged Aluminum, Marchesini 5-spoke.
  • Front: 3.50 x 17.
  • Rear: 5.50 x 17.
• Brakes (ABS optional):
  • 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.

Future model speculation

The ST4s was the pinnacle of performance for this line of Ducati motorcycles, and possibly the most sport-oriented touring motorcycle ever produced. Since the demise of the ST series this year, many people on internet bulletin boards have speculated that since the original chassis design of the ST series was borrowed from the Monster, a new ST based on the just-released Monster 696 chassis, but with the current 1098 Super-Bike engine might be in development. Ducati has previously stated that there will be numerous new models prior to 2010 (3 in 2008, 3 in 2009 and 4 in 2010), so it is possible that a new ST is in the works.

In addition, the sport touring segment is not an insignificant fraction of overall worldwide motorcycle sales. As well, older riders tend to prefer a more upright riding position and riding with a passenger, attributes that sport touring possesses. For Ducati to ignore this market completely would invite competitors like BMW, Honda and Yamaha to be the dominant players for sport touring motorcycles.

However, as of late 2008, Ducati has no stated plans to follow the ST series with another similar motorcycle. Ducati marketing has stated that the company's image is about racing, adventure and style, with less emphasis on sport touring. Customers who would have belonged to the ST category are now directed to the Multistrada as a replacement. But, few people seem to agree that this is a valid replacement motorcycle for the ST series, mostly due to the less-powerful engine being too weak for spirited two-up riding with luggage. Ducati has made public, in its factory plan for 2008-2010, that the overall percentage of models as of 2010 will follow this distribution: 30% Adventure (Multistrada/Hypermotard), 40% Naked Sport (Monster/Fighter/Sport Classic), 30% Sport (Super-Bike/Desmosedici). Since 2008, Sport Touring was eliminated as a model segment (7% as of 2007), so if there is to be a new ST it would be difficult to visualize such an entry in the Adventure category which normally is for Dual-Sport motorcycles.

Should a new model appear, it would fall into the Adventure product category based on the current lineup (model breakdown based on chassis platform):

Adventure 30% - 3 models

• Multistrada 1100/1100S (possible replacement in 2010)
• Hypermotard 1100/1100S (introduced in 2007)
• Unknown (possibly new 2010 model)

Naked Sport 40% - 4 models

• Monster 695 (696 introduced in 2008)
• Monster S2R 1000 (replacement 1100/1100S in 2009)
• Monster S4R Testastretta/S/Tricolore (replacement "Fighter" 1098 in 2009. Monster name has been dropped from liquid-cooled Naked Sport models)
• Sport Classic 1000 GT/Touring/Biposto/S (GT has a "Touring" trim-level model added)

Sport 30% - 3 models

• Super-Bike 848 (introduced in 2008)
• Super-Bike 1098/S/R (1098R introduced in 2008, 1098 will become the 1198 in 2009, possibly new 1198R in 2010)
• Desmosedici RR (introduced in 2007, all units have been purchased, no word on future versions)