Formula TT

The Formula TT was a racing class for motorcycles from 1977 to 1990 as the official World Cup under the umbrella of International Motorcycling Federation. It was in three engine capacity classes, and was divided into both two and four-stroke engines.
History.
From 1949 to 1976 the Isle of Man TT was part of the Motorcycle Grand Prix World Championship and was the home of the British Grand Prix. The event came under increasing scrutiny due to safety concerns despite efforts by the ACU to retain its world championship status. When Italian rider Gilberto Parlotti was killed during the 1972 TT, his close friend and the reigning world champion Giacomo Agostini, announced that he would never again race on the Isle of Man. More riders joined Agostini's boycott and by the 1976 season, only a handful of serious Grand Prix riders were among the entrants. Shortly after the 1976 TT, the FIM made the long-anticipated announcement that the TT, once the most prestigious race on the Grand Prix calendar, was stripped of its world championship status. The Grand Prix action was moved to the UK with the 1977 British Grand Prix being held at Silverstone.
The race authorities of the Isle of Man TT worked with Auto Cycle Union to set up a new formula that would include racing on the Isle of Man. This series was the result of that collaboration.
For the first two years all three formula were run as part of the Isle of Man TT:
In 1979 a second race was added:
For the start of the 1982 season Formula III was dropped and the number of circuits was increased:
For the remaining four seasons only Formula I races were run:
In 1988 a rival series called the Superbike World Championship started and as it proved popular and commercially successful, it was decided to end the Formula TT at the end of the 1990 season.
Technical regulations.
The TT Formula was divided into three categories: