This page covers used OEM parts for the Ducati Monster S2R and S4R, the premium sport-focused Monster variants produced in the mid-2000s. The S2R line (2005-2008) combined the single-sided swingarm and twin-stacked exhaust styling of the four-valve S4R with simpler, more affordable two-valve air-cooled engines in 800cc and 1000cc displacements. The S4R (2003-2008) used the liquid-cooled four-valve Desmoquattro and later Testastretta engines from Ducati's superbike line, creating the most powerful Monsters of their era. Sun Coast Cycle Sports carries inspected S2R and S4R components, each individually cataloged and shipped from Florida.
S2R and S4R models and parts compatibility
| Model | Years | Engine | Key details |
|---|
| S2R 800 | 2005-2008 | 803cc air-cooled 2-valve Desmo L-twin | Single-sided swingarm, twin stacked pipes. Air-cooled two-valve in sport chassis. |
| S2R 1000 | 2006-2008 | 992cc air-cooled 2-valve Desmo L-twin | Same concept as S2R 800 with larger displacement engine. |
| S4R | 2003-2006 | 996cc liquid-cooled 4-valve Desmoquattro L-twin | 916/996-derived four-valve engine. Single-sided swingarm. Ohlins suspension. |
| S4RS Testastretta | 2006-2008 | 998cc liquid-cooled 4-valve Testastretta L-twin | 999 Superbike engine. 130hp. Ohlins front and rear. Radial brakes. Top-of-line Monster. |
The S2R 800 and S2R 1000 share the same chassis, single-sided swingarm, bodywork, and most components. The difference is engine displacement (803cc vs. 992cc). Both use air-cooled two-valve Desmo engines. The S2R chassis is shared in concept with the S4R but differs in detail due to the different engine cooling requirements (air-cooled vs. liquid-cooled).
The S4R and S4RS use liquid-cooled four-valve superbike-derived engines that share no internals with the air-cooled two-valve S2R engines. The S4R uses a Desmoquattro engine from the 916/996 superbike, while the S4RS uses the Testastretta engine from the 999 superbike. These are different engine families despite both being four-valve liquid-cooled designs.
All four models share the single-sided swingarm design, twin stacked exhaust concept, and similar bodywork dimensions, but the specific chassis components differ due to engine and suspension variations. Bodywork panels and some bolt-on accessories may interchange across the S2R/S4R family.
Common S2R and S4R failure points and replacement parts
Desmodromic valve service (all models): Both two-valve (S2R) and four-valve (S4R/S4RS) Desmo engines require periodic valve service. The four-valve S4R/S4RS engines have twice as many valves to adjust, making their service more complex and expensive. Valve shim kits, cam belt kits, and gasket sets are critical for all models.
Liquid cooling system (S4R/S4RS): The four-valve engines require coolant system maintenance including hose replacement, thermostat service, and water pump seal inspection. Cooling system components are periodic replacement items.
Clutch wear: All models use wet slipper clutches that wear with spirited riding. The S4RS's 130hp output is particularly demanding on clutch components. Clutch plate kits and spring sets are common maintenance items.
Single-sided swingarm bearings: The single-sided swingarm pivot bearings wear over time and mileage. Swingarm bearing kits are a periodic maintenance item unique to the S2R/S4R family within the Monster lineup.
Exhaust system corrosion: The twin-stacked exhaust system's heat shields, headers, and mounting hardware corrode and deteriorate with age. Exhaust components are in steady demand for cosmetic and functional restoration.
Commonly replaced S2R/S4R parts
- Cam belt kit with tensioner bearings
- Valve adjustment shim kit
- Clutch plates and springs
- Exhaust headers and heat shields
- Single-sided swingarm bearings
- Coolant hoses and thermostat (S4R/S4RS)
- Chain and sprocket set
- Bodywork and tank
Frequently asked questions
Q: Do the S2R and S4R share the same chassis?
They share the single-sided swingarm concept and similar bodywork dimensions, but the frames differ due to the different engine types (air-cooled vs. liquid-cooled). The S4R/S4RS frames accommodate a radiator and liquid cooling system that the S2R doesn't need. Some bolt-on bodywork and accessories may interchange, but the frames themselves are not identical.
Q: Does the S4RS share its engine with the 999 superbike?
Yes. The S4RS Testastretta uses the 998cc engine from the 999 superbike. Engine internals cross over between the S4RS and the 999. The S4R (non-RS) uses the older Desmoquattro engine from the 916/996 family, which is a different engine. These two four-valve engines do not share internals with each other.
Q: Are S2R parts interchangeable between the 800 and 1000?
The chassis, bodywork, single-sided swingarm, exhaust, and most external components are shared between the S2R 800 and S2R 1000. Engine internals differ due to the displacement difference (different bore, pistons, cylinders). Any non-engine component from an S2R 800 should fit an S2R 1000 and vice versa.
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