Launched in June 1962, the B40 Sports Star SS90 had similar tuning modifications to the C15 SS80.
The compression ratio was raised to 8.75:1, larger valves and a bigger carburettor, which raised the power to 24 bhp (18kW) @ 7,000 rpm.
The machine was fitted with a roller bearing big end and a close ratio gearbox.
Initially UK SS90 models were distinguished by the chrome sides of the petrol tank.

Introduced in the US in 1963 as the BSA SS90, the American model was finished in blue and had chrome mudguards and rubber gaiters instead of metal fork shrouds.
In 1964, the US model was referred to as the Sportsman, and the UK model was fitted with the chrome mudguards.
In 1965 both variants were fitted with a separate headlight, the US version now being called the Super Sports.
Launched in June 1962, the B40 Sports Star SS90 had similar tuning modifications to the C15 SS80. The compression ratio was raised to 8.75:1, larger valves and a bigger carburettor, which raised the power to 24 bhp (18kW) @ 7,000 rpm. The machine was fitted with a roller bearing big end and a close ratio gearbox. Initially UK SS90 models were distinguished by the chrome sides of the petrol tank.
Introduced in the US in 1963 as the BSA SS90, the American model was finished in blue and had chrome mudguards and rubber gaiters instead of metal fork shrouds. In 1964, the US model was referred to as the Sportsman, and the UK model was fitted with the chrome mudguards. In 1965 both variants were fitted with a separate headlight, the US version now being called the Super Sports.
BSA B40