His racing career started in 1981 aboard a Suzuki TM75 in a local Junior Motocross Championship before eventually moving onto road racing in 1985. He won Malaysia's Superbike championship in 1991. In 1993 he was racing for Harris in the 500cc World Championship before joining the Suzuki factory racing team in the 250 class for the latter part of the season. He did not enjoy this, feeling that he is too large for the bikes.

For 1994 he joined countryman Aaron Slight on a semi-works Rumi Honda RC45 in the Superbike World Championship. After coming 5th overall in 1994, he started the 1995 season with Rumi Honda before replacing Doug Polen as the second factory rider alongside Aaron Slight, although they raced under different liveries. The bike gradually became more competitive, and Simon was strong in later part of 1995, coming 2nd in race 1 at Assen. He then spent 2 years with the Kawasaki racing team, scoring only one podium during the 1996 season finishing in 7th position. In 1997 he took two 2nd places and five 3rd places in addition to one Pole position and fastest lap to again finish 5th overall. In total he scored 10 podiums - four 2nds and six 3rds but, no wins in the series.

...
Wikipedia