It retained a flat-12 engine of 4942cc, but added four-valve heads and other mechanical changes for an output of 390 horsepower on European cars, 380 for U.S.-spec versions.

Capable of 70 mph, the four-valve head allowed more efficient gas flow and the spark plug could be positioned in the middle for optimum combustion.

The twin-cam four-valve head was replaced by the single-cam three-valve head, possibly from the Arab.

The engine has a four-valve head with splayed rocker arms to actuate the valves.

These had four-valve heads and were called 152E, they were of 89 x 80 mm bore and stroke and 1,995 or 1,998 cc (depending on the source).

The twin-cam four-valve head was replaced by a single-cam three-valve head, possibly from the Arab, the increase in bore to 120 mm allowing space for three valves.

Rudge engineer, George Hack, is said to have taken his design idea from the four-valve head Ricardo-Triumph Special of 1921, a one-off machine.

He designed a four-valve head for Rudge and in 1924 they produced their first four-valve cylinder head on a 350 cc engine.

After buying Ducati, Cagiva invested in the development of another V-twin, but with liquid cooling, and four-valve desmodromic heads.

The earlier 851 had introduced liquid cooling, computerized fuel injection and four-valve heads to the company's two cylinder motors.