1972 marked the year when Yamaha first produced engines with reed valves, called Torque Induction. This system helped deliver more low-end power and quicker engine response over the entire RPM range. All 1972 MX and Enduro models had reed valves, except the JT-2 Mini Enduro, which had rotary valve induction. This was also the first year for CD ignition, which came standard on the RT2-MX (360cc).
