[2] Without any financial or mechanical support from the Kawasaki factory, Simmonds spent the 1967 and 1968 Grand Prix seasons sorting out the motorcycle's reliability issues.

[3] This regulation change caused the dominant Yamaha and Suzuki factories to withdraw their teams from Grand Prix racing.

[1][5]Simmonds won his first 500cc class victory at the season ending Spanish Grand Prix at Jarama when Agostini sat out the race after already winning the championship.

[2] In 1972, while attending a non-championship motorcycle race at Rungis near Paris, Simmonds was killed in a fire caused by an exploding gas cylinder in a caravan owned by fellow racer Jack Findlay.

[2][6] Mistakenly thinking that Findlay was inside the caravan, Simmonds rushed to help just as the gas cylinder exploded, engulfing him in flames.