Manufactured in Torino, 1946, this unique machine has several advanced features.
Giuseppe Salvai of Torino, owner of a workshop specializing in high quality drum brakes which were later adopted by major manufacturers such as Aermacchi and Rumi, began in 1946 developing a 500cc engine and built several prototype motorcycles.
Concurrently Stilma (Sociéta Torinese Industrie Lavorazioni Meccaniche Affini) made a foray into the motorcycle market and installed a Salvai engine in a frame designed by Giuseppe Molino.
Among the interesting solutions adopted by the Stilma is the cantilever rear suspension with a double arm that forms a deformable parallelogram, with a compression spring mounted on a tube placed beneath the seat.
The central part of the chassis is made of pressed metal, with a tubular front member from the steering head supporting the engine.
A steel rear guard covers both the oil tank and battery and has a small passenger seat. Seen from the front, the front mudguard is intgral with the telescopic forks, a design feature that may be considered one of the first forms of aerodynamic fairing (and had been seen on a few other earlier makes).
The fuel tank is divided into two compartments, and a magdyno supplies current to the Magnetti Marelli headlight and horn. The headlight housess a Veglia speedometer and an oil pressure gauge.
Wheels are 21" front and 19" rear.
The engine is a 499cc single-cylinder with overhead valves, dry-sump lubrication and a single Dell'Orto carburetor, with to a four-speed gearbox, shift lever on the right.
The short light alloy pushrods (a concept copied from Velocette engines) aimed at maximizing inertia forces without resorting to the complication of an OHC setup, and without losing RPM and relative power. Another notable feature is the hemispherical combustion chamber, with the collectors placed together at a certain angle between intake and exhaust, inducing the intake of the mixture to a rotating movement in the chamber itself, improving the mixture and consequently carburation.
The motorcycle was decidedly futuristic, but very expensive to produce. It was presented at the 1950 Turin Automobile Show but unfortunately did not find a financial backer.
A Stilma machine with a Salvai engine exists in a private collection. It was photographed by Sotheby’s in 2011, and some of those images are available on the Facebook page of Sergio Scalerandi, to who this article is credited..
