Ducati Desmodromic 500GP
With Phil Aynsley
Well who’d a thought it! My 100th column. To mark this unlikely event here is a bike of not only major historical significance but a Ducati as well!
Over the years one Ducati I was most keen to photograph was the rarest V-twin – the 500GP. However they aren’t the easiest bike to track down (apart from the one in the Ducati Museum), so it took me until a visit to Germany in 2016 to finally get one in front of my lens.
The 500GP twin was developed from late 1970 and was intended as a ‘proof of concept’, in order to help the sales of the 750cc road bike that was just entering production. While the motors shared the same basic L-twin layout, the 500s used a much squarer bore/stroke ratio and was equipped with Desmodromic valves from the outset.
Its first race was at Modena in March 1971, and while the original factory chassis was initially used, it was replaced from August onwards by a Colin Seeley commissioned frame. The front drum brake was also changed to a disc before proper racing was begun.
Riders during this first year were Bruno Spaggiari, Phil Read, Ermanno Giuliano and Gilberto Parlotti. It was Parlotti who gave the 500GP its only victory – at a non-championship race in Yugoslavia in May.
Read scored a second behind Agostini at San Remo with other 500GPs in third and fourth places. He also finished fourth at Monza. Spaggiari and Paul Smart finished third and fourth respectively at Imola the following year.
The 500 project took a lower priority to the successful Formula 750 bikes so were never developed to their full potential. Engineer Taglioni did experiment with the design however.
A four-valve head was tried in ‘72, but it made 69hp compared to the two-valve heads which had reached 71hp by that stage. Fuel injection was also experimented with the same year but this went nowhere as the FIM banned its use.
In 1973 Taglioni employed noted engineer Renato Armaroli to develop the 500 further. A belt-driven DOHC, eight-valve was the result. It was raced several times during the year by Spaggiari but without success. Its output of 74hp was not much of an advance on the two-valve motor.
Of the five 500GPs built this one is probably in the most original condition.
In a strange coincidence, a few days later the owner of the next collection I visited in Germany was showing me his bikes and what should I spy but another 500GP!