The AJS S3 V-twin is a British motorcycle designed and built by the Wolverhampton, England company A. J. Stevens & Co. Ltd.

Launched in 1931, the AJS S3 was a 496 cc transverse V-twin tourer with shaft primary drive (but chain final drive), three-speed bevel-driven gearbox and alloy cylinder heads.

The 50 degree V configuration was effective for air cooling and with a tank top 'dashboard' was conceived as a luxury cruiser.

It had been expensive to develop and at £65 was more expensive than the 1,000 cc (61 cu in) AJS of the same year,[1] so the S3 did not sell in large numbers, and by the end of 1931 AJS had gone into liquidation and been taken over by Matchless motorcycles who discontinued production.

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