The Ducati 239 Mark 3 is a 239cc (14.6cuin)single cylinder bevel drive SOHC motorcycle produced by the Italian manufacturer Ducati in limited quantities[4] for the French market in 1974. The French Government has announced that they were to increase VAT on motorcycles of 240 cc and above in 1975. Ducati responded by producing the 239 to take advantage of the lower 20% VAT rate on sub-240 machines.[1] To compensate for the reduced capacity, the engine was tuned to produce more power[5] with a different camshaft,[1] slipper piston, 30 mm carburettor and a different exhaust using a Lafranconi silencer.[5]
The factory ceased production of OHC singles in 1974. The remaining stocks were purchased by the then British importer Coburn & Hughes, including some 239s, who continued to sell them until early 1976.[5]
Total production was around 400 machines; 250 Mark 3s and 150 Mark 3Ds.[6]
Technical details
Engine and transmission
The single cylinder bevel drive OHC engine was of unit construction and had alloy head and alloy barrels with cast iron liners and was based on the 'wide case' engines used in the racers.[2]bore and stroke were 72.5mm ×57.8mm (2.85in ×2.28in) giving a displacement of 239cc (14.6cuin).[1] Coil valve springs were fitted which was a departure from Ducati's normal practice of fitting hairsprings on the OHC singles.[7] Claimed power output was 22bhp (16kW) @ 7,500 rpm.[1]
An additional version of the 239 Mark 3 was offered, the 239 Mark 3D, also for the French market, that was fitted with a different head that used desmodromic valves.[11] (A system where the valves are positively closed by extra lobes on the cam and levers rather than by a more conventional springs).[12] The desmo was fitted with a disc brake on the front.[9] Around 150 desmos were made.[6]