As Ducati’s superbikes evolved, so too did the Monster lineup. But by the middle-aughts, the Italian marque was facing increasingly fierce competition from fellow European manufacturers like Triumph and KTM. So in 2006, Ducati shoehorned the powertrain from its 998 superbike into the Monster. Two years later, Ducati one-upped itself, this time delivering what was essentially a naked version of its World Superbike Championship-winning 999 model.
Dubbed the S4RS, the naked was powered by Ducati’s Testastretta 998cc engine. The water-cooled narrow-head motor featured Marelli FI with competition-derived 12-hole injectors and an auxiliary oil cooler. The race-bred L-Twin redlined at 10,500 rpm, putting down 130 hp at 9,500rpm and 77 ft-lbs of torque at 7,500rpm. Despite being housed in Ducati’s trademark tubular trellis frame, the company’s designers did a stellar job of hiding the model’s slew of wiring and sensors so they could highlight the crown jewel of the bike: the engine.
The 390lb (177kg) S4R S also boasted an array of competition-grade componentry, much of it borrowed from the R-spec 999. 43mm inverted Öhlins forks with low-friction titanium nitride coating, Öhlins monoshock, aluminum single-sided swing-arm, four-pot Brembo P34 brakes with dual 320mm discs, and forged ten-arm alloy Marchesini rims were all standard fare on the hopped-up naked.
This example is VIN: ZDM1RB5T57B104544. The seller acquired it from a private party five years ago.
During his ownership, the seller covered 3,000 miles. The odometer shows 17,916 miles.
Maintenance:
“All maintenance and repairs done by myself”
17,900 miles Oil/filter change and O2 sensor
17,900 miles – Cam belt change (December 2025)
17,400 miles – Fork Oil and seals
17,000 miles – Starter Clutch replaced
15,100 miles – Barnett Clutch
15,000 miles – Valve check and adjust, Oil/filter change
The seller notes some swelling of the tank.
Modifications:
Carbon fiber clutch cover.
Aftermarket levers.
Ducati Corse sticker on tail, Monster sticker on wheels.
Battery tender lead.
Inside of the tank:
It is riding on Pirelli Diablo Rosso III tires with date codes of 2317 and 2019.
The sale includes two black keys, the red key, and the owner’s manual.
Cosmetic Blemishes: please see the album in the “Photos” tab for all known cosmetic blemishes. Here is a selection:
Currently located in Arroyo Grande, California, this Ducati is offered on a clean California title with registration current through September 2026.
Have any Monster S4RS stories or questions about this listing? Let us know in the “Comments” tab!
