1977 Ducati 500GTL

Make Model	Ducati 500GTL
Year	1977
Engine	Four stroke, parallel twin cylinder, SOHC, chain driven, 2 valve per cylinder
Capacity	496.9 cc / 30.2 cu in
Bore x Stroke	78 x 52 mm
Compression Ratio	9.6:1
Cooling System	Air cooled
Induction	Dell'Orto PHF30BS/BD
Ignition	Points and coil
Spark Plug	Champion L81
Starting	Kick
Battery	Yuasa Y50-N18L-A1, 12V 18Ah
Max Power	25.7 kW / 35 hp @ 6500 rpm
Clutch	Wet, multiplate
Transmission	5 Speed
Primary Drive Ratio	2.125:1 (32/68)
Gear Ratios	1st 2.500 / 2nd 1.714 / 3rd 1.333 / 4th 1.074 / 5th 0.900:1
Final Drive Ratio	2.923:1 (13/38)
Final Drive	Chain
Front Suspension	35 mm Marzocchi telescopic fork
Rear Suspension	Swing arm, 2 x Marzocchi shocks, 3-way adjustable
Front Brakes	2 x 256 mm Brembo discs
Rear Brakes	Single 160 mm drum, leading shoe
Front Tyre	3.25-18
Rear Tyre	3.50-18
Dimensions	Length: 2080 mm / 81.9 in Width: 840 mm / 33.1 in Height: 1100 mm / 43.3 in
Wheelbase	1400 mm / 55.1 in
Seat Height	760 mm / 29.9 in
Dry Weight	170 kg / 374 lbs
Wet Weight	196 kg / 432 lbs
Fuel Capacity	19 L / 5.0 US gal / 4.2 Imp gal
Consumption Average	5.3 L/100 km / 18.7 km/l / 44 US mpg / 52.8 Imp mpg
Braking 100 km/h - 0	40.5 m / 133 ft
Standing ¼ Mile	14.9 sec @ 138 km/h / 85.9 mph
Top Speed	170 km/h / 105.6 mph

The oil crisis of 1973 convinced Ducati’s management of the time that a new, cheaper range of models were required and they decided that these bikes needed to be parallel twins. Ducati are renowned for their V-twins, but they’ve produced parallel-twins too

This was despite Ducati’s great record of achievements from their single-cylinder motorcycles followed by Fabio Taglioni’s success with his 750 V-twins and the work he had already completed on what was to become the Pantah.

Taglioni would have nothing to do with the development of the parallel twins which saw Ing. Tumidei overseeing the design which stressed reduced manufacturing costs as a primary goal.

While Ducati had shown prototypes of two different 500 parallel twins in 1964 and 1968 the new design had nothing in common with them. Originally conceived with a 360º crankshaft, this was soon changed to a less 180º crank for less vibration. The new GTL parallel twins would arrive in 350 and 500 cc versions in 1975

However the massive crankcases, built to house large counter-balancers were retained. Chain-driven valve-spring SOHC heads were used for the GTL models with both 350 and 500 cc versions being debuted in 1975. Almost an afterthought, the Sport Desmo versions weren’t available until almost two years later.

The GTLs shared the same basic Giugiaro styling as the 860GT and were just as unloved!

In addition to the styling the bikes suffered from poor reliability – the main problem being the oil feed to the camshaft. They also suffered from very modest performance, especially the 350.

Only 1,105 500s and 930 350s were built before they were replaced by the GTV in 1977. This employed the successful (Tartarini) styling of the Sport Desmo and the Darmah but retained the valve-spring heads of the GTL. The oil feed problems were largely remedied in these later motors.

The 500GTL made 35 hp at 6,500 rpm and had a dry weight of 170 kg, while top speed was 170 km/h.