The biggest difference between each model lies in the number of valves and displacement of the engine.
ST2 (2-valve model / 1997–): Features a 944cc liquid-cooled 2-valve (Desmodromic) engine. With strong low-to-mid-range torque and a mild character that’s easy to handle and durable for a Ducati, it’s a practical long-distance tourer.
ST4 / ST4s (4-valve model / 1999–): Equipped with the liquid-cooled 4-valve (Desmo Quattro) engine from legendary superbikes like the 916 and 996. This high-revving powerhouse is the most sport-oriented in the series, with the “S” model adding premium touches like Öhlins rear suspension and lightweight wheels.
ST3 / ST3s (3-valve model / 2004–): Featuring a newly designed 992cc liquid-cooled 3-valve (Desmotré) engine that takes the best from both ST2 and ST4. It’s the series’ ultimate expression, combining low-end torque with high-rpm power. The styling received a minor refresh, and later models adopted a wet clutch for superior maintenance.
So that’s it… ST3 came last… The more you learn, the more niche it gets… Maybe collecting all 2, 3, and 4 models?
Today’s maintenance & inspection log
Bike: DUCATI ST3
A connoisseur’s choice sport-tourer with the rare “liquid-cooled 3-valve (2 intake, 1 exhaust)” engine found among Ducatis.
Work performed:
Comprehensive inspection and maintenance for continuous registration (Deco-mainte).
Engine oil change.
Complete coolant replacement and air bleeding.
Result: Fresh blood (oil) and coolant mean the heat-prone L-twin engine is now safe and sound. The inspection passed without a hitch!
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Can’t change the coolant without removing the upper fairing
You might think you could squeeze by… tempting fate. Maybe with some sketchy workaround? But removing the upper fairing is way faster.
It uses a super self-weight reservoir tank design. As you can see “Remove the radiator cap and the reservoir fluid drains right out.” Whoever designed this had a twisted sense of humor.
The cap has an iron sleeve inside. I cleaned it but it didn’t come out spotless (；∀；) If the price is reasonable, replacement might be worth it.
Various items like crush washers need to be in stock
Replacing them makes future work go smoothly. I’m out of C550 stock, so I need to order more…
The spike in material costs lately is really shocking.
This time I rode it to the inspection myself.
It just won’t fit no matter what. If I remove the screen and mirrors, maybe… it could work. Since it’s completely stock, I just rode it as is.
Riding it there leaves zero room for error, so it was a bit nerve-wracking. Those folks doing user inspections are seriously impressive!
The more you ride it, the more appealing the ST3 becomes. Used ones are reasonably priced and in decent shape—actually a solid buy! All done!
Servicing the Rare DUCATI ST3: Vehicle Inspection, Oil, and Coolant Change.
Vehicle: DUCATI ST3. Details: This bike is quite the enthusiast’s choice! It features a rare liquid-cooled 3-valve Desmo engine, designed to offer the best of both the 2-valve and 4-valve models. Work: Along with our thorough pre-inspection maintenance, we removed the full fairings to replace the engine oil and the engine coolant. Since L-twin engines run hot, fresh coolant and proper air bleeding are absolute musts to prevent overheating. Verdict: The bike passed its inspection with flying colors and is ready for the spring touring season!
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