The Ducati 851 is a fully faired sport bike with liquid cooling and four-valve desmodromic heads, built by Ducati between 1987 and 1992 and succeeded by the 888. It was the first new model after Cagiva bought Ducati in May 1985, and the first of a long line of four-valve twins.
Ducati 851 at a glance
| Maker | Ducati, Borgo Panigale (Cagiva group) |
|---|---|
| Production | 1987–1992 |
| Designer | Massimo Bordi |
| Engine | 851 cc Desmoquattro, 90° V-twin, liquid-cooled, four desmodromic valves |
| Valve angle | 40° included |
| Frame | chrome-molybdenum steel trellis, engine as a stressed member |
| Brakes | Brembo, fully floating front discs from the update |
| Wheels | 16-inch at launch, 17-inch from 1988 |
| Successor | Ducati 888 |
History of the Ducati 851
The 851 replaced the air-cooled two-valve 750 F1 and marked Ducati’s return to the technical front after years of relying on two-valve engines. Cagiva’s owners, the Castiglioni brothers, invested in a new liquid-cooled, four-valve desmodromic twin, and Massimo Bordi’s ideas, first written as his 1973 thesis at the University of Bologna, finally reached production as the Desmoquattro.
The engine was based on the Pantah motor but with liquid cooling, fuel injection and four-valve desmodromic heads with a 40-degree included valve angle. Bordi worked with Cosworth on the heads, and although the British engineers believed a smaller angle was possible with valve springs, Ducati stayed with desmodromics. The first prototype was a 748 cc racer based on the 750 F1 and was entered at the Bol d’Or in 1986; the production 851 used stronger crankcases and a larger 92 mm bore.
The first series, the 1988 851 Tricolore, was criticised for its handling because supply problems meant it went on sale with 16-inch wheels instead of the intended 17-inch ones. The right wheels, together with suspension and engine changes, arrived from 1988 with the classic red livery. In 1989 came the 851 Superbike (S3) with Marzocchi M1R forks; 1990 brought more power and Showa upside-down forks. The 888 of 1991 was the racing evolution, and in 1990 Raymond Roche gave Ducati its first Superbike world title. Ayrton Senna was a notable owner.
Design and features
- Desmoquattro engine: liquid cooling and four desmodromic valves, a first for a production Ducati.
- Stressed-member frame: the chrome-molybdenum trellis also carried the rear swingarm.
- Racing success: nine World Superbike wins with Roche and Falappa, and the 1990 title.
- Tricolore: the first series wore the Italian flag colours that later returned on limited editions.
Ducati 851 versions
- 851 Tricolore (1988): the first series with 16-inch wheels and Italian flag paint.
- 851 Superbike S3 (1989): red livery and Marzocchi M1R forks.
- 1990 update: more power, Showa upside-down forks and more tapered side panels.
- 851 Strada (1992): the road model still listed alongside the 888 SP4 and SP4S.
The 851 was the ancestor of the 888, the 916 and the Monster, which used the same chassis layout. More Ducatis are in the Ducati collection.
Video: 1989 Ducati 851 Superbike
Video by Leon on YouTube.
Sources
- Ducati 851, English Wikipedia: development, design, racing
- Ducati 851, Italian Wikipedia: history, engine, series, racing
