Sylvain Geboers was born on the 28th of March in 1945. He lives in Mol, which is the Flemish part of Belgium where the sand tracks are plentiful. He soon became interested in motocross. He started racing by the time he was 16, straddling a big-bore, heavy 4-stroke machine. At the age of 17, Sylvain won his first title and became the national junior champion in the 500cc class. Geboers rode a sturdy BSA Goldstar, which he managed with impressive strength. A year later he was representing Belgium at the team world championship that were run at Hawkstone Park. They finished second at this Moto Cross des Nations, which was Geboers first big breakthrough. With this impressive ride Matchless offered the young Belgian support for the 1965 season when Sylvain yet again was a member of the Belgian 500-team coming home as silver men at the MCdN.
For 1966 Sylvain Geboers had ties with the Swedish performance tuner Lindström, who contracted the Belgian to race in the half-litre championship. Lindström had close ties with Husqvarna and it was these 2-stroke machines that were turned around according to Lindström's technical knowhow. Sylvain returned the favours by clinching his first WC points when he finished third in the Danish Grand Prix. This rendered him his initial four career points. But the season was a big disappointment and did not result in any further points. He came 16th in the final standings, which tempted the Belgian to switch brands for 1967.