[3] Kempster earned the nickname 'Smiling Jim Kempster' and came to prominence in 1928 when he won a race against Roger Frogley, in a match deemed to be the English Championship.
[4] He earned significant prize money during 1928 and won an International title in front of 45,000 at the new Wimbledon Stadium.
[5] He joined the Wimbledon Dons for the inaugural speedway season in England.
[1][7] Kempster continued to ride in the top tier of British Speedway from 1929 to 1933.
[10] He was killed in a plane crash on 29 June 1945, while serving with the Air Transport Auxiliary during World War II[11] and is buried at the Rheinberg War Cemetery.