Back in the 1960s and 1970s, Yamaha produced a range of small displacement trail bikes meant to cater to the burgeoning off-road market. Though many motorcyclists are familiar with the DT series, there were several others, too, such as the AT, the LT, and the HT like you see in these photos Powered by an air-cooled two-stroke 90cc single, the HT-1 made approximately 8.4hp and 6.5lb-ft of torque. Thanks to the bike’s svelte 187-pound curbweight, those numbers proved more than enough to enable some fun in the dirt. The HT-1’s specs also made it an attractive option for beginners — whether those new to motorcycling or those simply inexperienced off the beaten path.