[7] As a young boy, he attended speedway races with his father at New Cross Stadium, where he cheered for his idol Johnson and dreamed of becoming a racer himself.

[8] Through an American friend, Grant received a job offer at a motorcycle garage in Hollywood, California, and in November 1961 at the age of 21, he loaded his Norton Manx aboard the SS Rotterdam bound for New York City.

[3][7] Grant began competing and winning semi-professional road races organized by the American Federation of Motorcyclists (AFM), riding a 250cc Parilla motorcycle.

[2] His successful performances in AFM races qualified him to compete in the 1963 United States Grand Prix where he finished second to Yamaha factory rider Fumio Ito.

[3][4][11] He also had an impressive victory at the 1964 Dodge City National, where he won the 250cc Amateur Class after starting the race from the last row on the grid.

[7] He rode the new Suzuki X6 to a third place behind Cal Rayborn (Harley-Davidson) and Dick Mann (Matchless) in the 1966 250cc Carlsbad, California national race.

[20] The Suzuki T500 began to show its potential at the National road race in Indianapolis, when both Grant and his teammate Art Baumann finished in second and third places behind Cal Rayborn.

[7][22] At the final road race of the season held at Sears Point Raceway, Baumann and Grant were running in first and second places, however Grant had placed such confidence in his Suzuki, that he neglected to service the motorcycle after his land speed records and a mechanical failure forced him to abandon the race.

[29] At the season-ending race held at the Ontario Motor Speedway, Grant placed third behind John Cooper (BSA) and Kel Carruthers (Yamaha).

[31] Grant's strong performances in AMA competition earned him a place on the North American team for the 1972 Transatlantic Trophy match races.

[3] The Transatlantic Trophy match races pitted the best British riders against the top North American road racers on 750cc motorcycles in a six-race series in England.

[33] Grant briefly led the 1973 Daytona 200 but abandoned the race due to a broken chain, allowing Jarno Saarinen to claim the victory.

[34] At the 1973 Transatlantic Trophy, Grant took the lead at the first heat race at the Brands Hatch Circuit, but was struck by Paul Smart as they entered the first turn, causing him to crash.

[38] In 1974 Grant sponsored Hennen on a Yamaha TZ700, on which the latter scored the first major victory of his motorcycle racing career at the Daytona International Speedway when he set the fastest qualifying time and won the Junior Class event.

[37] The 1973 oil crisis severely impacted all forms of motorsports in the United States and Suzuki made the decision to withdraw their team from the AMA national championship at the end of the 1975 season.

[39] Grant later invited a 16-year-old Randy Mamola to participate in the New Zealand Marlboro Series, providing him with valuable racing experience.