A Brief History of the Marque
Manufactured in Binzago, Cesano Maderno, Milano, 1974-1986 and later
The company's first engine was designed by the engineer Dr. Aroldo Trivelli of Milan, an air-cooled disc valve 125cc two-stroke for go-karts. After thorough testing the Trivelli engine was fitted to a motorcycle.
In 1976 the Tau TVR (Tau Valvola Rotante) appeared with a six-speed gearbox. It had three transfer ports and electronic ignition. Fitted to a racing motorcycle it achieved 200 km/h, developing 27 bhp at 11,000 rpm. The TVR did not prove suitable for installation on a motocross bike and Trivelli agreed to modify it to achieve a naturally aspirated engine more suited to off-road.
The Tau, with a rotary valve water-cooled version of the engine, was shown at the Milan Motosalone in 1977.
In 1979 the company formed a business relationship with a British manufacturer that required engines from 100cc for enduro work. That year Tau released a 250cc engine which was fitted to the Cabrera - it produced 38 hp at 8000 rpm.
Tau reed-valve 125cc engines were fitted to HRD machines in 1985, Aspes in 1982, and to Ancillotti off-road bikes including the 1981 125RC.
The engines were also fitted to the Panda and Valenti trials machines, and to A.R.M. enduros of Spain.
A Tau engine of most unusual configuration was built for the Bimota V-Due. It has the appearance of a V-3, with the centre cylinder having four bores which are part of the fuel injection tract, which proved to be the Achilles heel of the V-due and led to financial disaster for the firm - through no fault of Dr Trivelli, it would appear.
List of manufacturers who fitted Tau engines:
Sources: MC Storico Conti, et al.