Moto Guzzi’s 1954 in-line 500/4 Racer
With Phil Aynsley
In a recent column I looked at Moto Guzzi’s eye-catching first attempt at a four-cylinder GP motorcycle (Link). In this column we look at its second attempt.
The final race of the 1952 season, the Italian GP, was the venue for its debut. The design had been outsourced to Carlo Gianini (who was responsible for the original OPRA motor that eventually became the supercharged Rondine 500/4).
Gianini came up with an unusual longitudinal in-line four motor that was initially fitted with a mechanical/pneumatic fuel injection system. The DOHC heads incorporated valves that closed directly onto the heads, without any inserts. Final drive was by a shaft.
While fast the bike suffered from being overly complex, having a high centre of gravity and a difficult gear change action due to the shaft drive.
The multi-plate clutch also proved to be too small but that wasn’t able to be corrected without entailing a complete redesign of the rear of the motor.
Carburettors replaced the injection for 1954 as well as a dustbin fairing that incorporated pannier fuel tanks. This bike is fitted with the original fairing however.
The riders didn’t like the bike and it only achieved two victories, both in non-championship races. The design was shelved at the end of the 1954 season when the V-8 took over 500cc duties in 1955.
Power for the Moto Guzzi 500/4 Racer was 55hp at 9000rpm, while weight just 145 kg. A top speed of 230 km/h was possible.