1974 MX100A The MX100 series Yamaha followed the Low production, class leading LTMX series bikes that were the dominant bikes in their class in 72 and 73. In 74 they did major changes to the bike as their now was plenty of competition. Mainly the TM100 Suzuki. Still 2 years from the first YZ100, these were the bikes that you raced. Most survivors are left to trail riding bikes.