Ducati 350 Mark 3D

Make Model	Ducati 350 Mark 3
Year	1968-70
Engine	Four stroke, single cylinder, SOHC, bevel gear driven
Capacity	340.2cc / 20.8 cu in
Bore x Stroke	76 x 75 mm
Compression Ratio	9.5:1
Induction	Dell'Orto SS129D
Ignition	Points, coil, 6V30W generator
Battery	Yuasa B38 12Ah
Spark Plug	Marelli CW260N / Lodge 2HN
Starting	Kick
Max Power	24.8 kW / 34 hp @ 8500 rpm
Clutch	Wet, multiplate
Primary Drive Ratio	2.111:1
Transmission	5 Speed
Gear Ratios	1st 2.46 / 2nd 1.73 / 3rd 1.35 / 4th 1.10 / 5th 0.97:1
Final Drive	Chain
Final Drive ratio	3.214:1
Front Suspension	31.5 mm Ducati telescopic hydraulic fork
Rear Suspension	Swingarm, Twin Marzocchi shocks, 3-way adjustable
Front Brakes	180 mm Drum
Rear Brakes	160 mm Drum
Front Tyre	2.75-18
Rear Tyre	3.00-18
Dimensions	Length: 2000 mm / 78.7 in Width: 600 mm / 23.6 in Height: 940 mm / 37.0 in
Seat Height	735 mm / 28.9 in
Dry Weight	128 kg / 282 lbs
Fuel Capacity	15 Litres / 4.0 US gal / 3.3 Imp gal
Top Speed	170 km/h / 106 mph

In 1967, Ducati launched a redesigned frame featuring twin tubes running from the back of the gas tank down to the swingarm pivot. This new frame required a wider rear engine case mount — approximately 3 inches wider than the front — and these subsequently became known as “wide case” engines. Between the two styles, narrow and wide case, the basic architecture remained the same.

Ducati brought the new frame and wide case engine design to the street in 1968, first in the street-legal 350cc Scrambler, then also in 250cc and 450cc models. All of these used a bevel drive overhead cam with valve springs. During 1968, Ducati finally brought a desmo to the street with the launch of the 250 and 350 Mark 3 D — “D” for Desmo.

The 1968 Ducati 350 Mark 3 Desmo featured a red frame, a red and chrome gas tank with twin-filler caps, chrome fenders, steel rims, a high-lift cam and a tachometer. In 1969, the 250 and 350 were joined by a 450 Mark 3 Desmo, and they were outfitted with a black frame and a single-cap fuel tank and chrome fenders. Non-desmo Ducatis feature a dull silver paint in place of the chrome.

Ducati’s 350cc single-cylinder desmo engine is all alloy with polished cases and massive finning on the barrel, which features a cast iron liner. Bore and stroke are 76mm by 75mm for a capacity of 340cc, with a 10:1 compression ratio. The 5-speed unit construction gearbox has a heel/toe shifter on the right side of the engine, with the kickstarter on the left.

Cycle magazine tested the Mark 3 D Ducatis, including the 250, 350 and 450 models, which, apart from engine size, are of the same overall dimensions. “The Ducati’s single-cylinder engine has narrow cases; therefore, the frame, the tank and the footpegs can all be very narrow, too. You can fit yourself more easily to a well-laid-out narrow motorcycle than you can to the fat bikes, and the result is a feeling of instant confidence … the Ducatis feel as though they had been built just for you, and that they weren’t something that came out of a crate,” Cycle said.

Of the 350cc desmo engine, they wrote: “The 350 was more highly tuned and had a narrower powerband; the power came in at about 6,500rpm. The 350 is tuned as a street dragster; the 250 and the 450 are over-the-road bikes.”

Source: Motorcycle Classics