The final took place on 29 December 1990 at the 300 metres (330 yd) long Riverview Speedway in Murray Bridge.
Shane Parker scored a virtually unchallenged 15 point maximum to claim his first South Australian Championship.
Defending champion Scott Norman was hampered by bike troubles on the night and never posed a threat to Parker.
Shane Bowes, who was one of the favorites to take out the title after breaking the 4 and 6 lap records at Riverview earlier in the month (after having done the same the previous night at North Arm in Adelaide), was unable to ride in the meeting due to lodging his nomination form one day too late.
Bowes and Scott Norman would later get their chance to qualify for the Australian Championship in Alice Springs when they finished 1st and 2nd respectively a special last chance qualifying round arranged due to the large number of leading riders (mostly from New South Wales and Queensland) who had failed to qualify through the various state championships.