The tiddler twins

Yamaha’s obsession with sub-25cc twins began in 1965 with the launch of JDM (Japanese Domestic Market) AT90 (below) which grew to be the full 100cc YL1 in late 1966 running until 1971. A sports 100 HS1 was launched in 1968 and aimed at new riders who were limited to sub-125 machines. The YL1 was offered in 6 volt, 12 volt and electric start versions and later became the YL3 with chrome front guards, an extra gear and candy scheme. The HS1 was latterly refreshed for 1972 to become the HX or HX90 and sold as a JDM looking remarkably similar to the 125cc AS3. Although the market 90 and 100cc machines had been relatively good, the sales of similarly physically sized 125s had been much better. Crucially, the 125s were quoted at around 15bhp against the 10bhp of the smaller twins and that was a huge come-on for teenagers, so Yamaha quietly pulled the plug on the smaller twins to concentrate on the eight-litre baby missiles.