His parents bought him a junior speedway bike and he had his first ride at the Olympic Park Speedway in Mildura in 1985, although his home track was the Sidewinders Speedway in the Adelaide suburb of Wingfield, a 112m long track run by the Sidewinders Junior Speedway Club solely aimed at junior Motorcycle speedway development. Within a few seasons Sullivan was seen as one of the best junior riders in South Australia, winning the South Australian Under-16 Individual title in 1990 and 1991 while winning the Pairs Championships in 1988, 1989, 1990 and 1991.