Five years after Soichiro Honda’s Isle of Man TT declaration, on June 3, 1959, Honda debuted in the FIM Road Racing World Championship Grand Prix (WGP) Isle of Man TT races in the 125cc class. The racing bike developed for this race was the RC142 factory bike powered by an air-cooled, DOHC 4-stroke, 4-valve, 2-cylinder 125cc engine. Three Honda associates, each riding an RC142, completed the Clypse course. Naomi Taniguchi finished sixth, Giichi Suzuki was behind him in eighth, and Junzo Suzuki eleventh despite severe brake problems. The exceptional results on its debut were proof of the bike’s high potential. In this race, Taniguchi earned the Silver Replica Trophy, awarded only to high achievers. The RC142 helped Taniguchi to become the first Japanese to claim a WGP award, and Honda to win the Manufacturer Teams prize.
Taniguchi’s lap time of 1 hour 34 min 8s was, however, 6 min 43s slower than race-winner Tarquinio Provini (MV Agusta), an average lap speed difference of 10km/h. Honda’s first Isle of Man TT was a race demonstrated how much it would have to improve to challenge the world’s fastest machines. By racing in the Isle of Man TT, Honda identified the bike’s problems - lack of rigidity causing bad handling, and brake performance - and applied improvements to its next racing bike, the RC143. The RC142’s performance nonetheless led to Honda taking its first WGP win in the 1961 Isle of Man TT races.