In 1976, Yamaha took a chance on the 19-year-old Hannah, who was largely unknown outside of the local Southern California motocross scene. Yamaha signed Hannah to race the 125cc outdoor nationals. He started out the year by winning all 5 races in the 500cc class at the Florida Winternational Series (a warm up series), but his real strength was on the 125cc bikes at the outdoor motocross circuits. He won five of the eight 125cc nationals that year en route to the championship. In 1977, Hannah hopped aboard a Yamaha 250 and won the AMA Supercross Championship in impressive fashion, taking six of the 10 rounds. He would go on to win the AMA Supercross title for three straight years.
In 1978, Hannah moved up to the 250cc ranks in the outdoor nationals with devastating results for his competition. He won a record eight consecutive 250 outdoor nationals, a record that still stood at the time of Hannah’s 1999 Motorcycle Hall of Fame induction. In 1979, he came back and dominated the 250 outdoor nationals again, handily winning the 250 MX title by earning victories in six of the 10 events.
A water skiing accident in the Colorado River at the end of 1979 nearly cost Hannah his career. His right leg was broken in 12 places when he hit a submerged rock and was catapulted onto the riverbank. Doctors initially told Hannah he would never be able to race again. He was forced to sit out the entire 1980 Supercross & 250 outdoor nationals series while recuperating, but returned late in the year to contest the Trans-USA series. During his recovery Hannah earned his pilot license and for the first time in his adult life found interests outside of motorcycle racing.
Hannah never was quite able to capture the magic he had during the 1970s. While he won 20 nationals during the 1980s, he never was able to capture another championship. His best results in the ‘80s were a second-place finish in the 250 MX series in 1981 and third in the same series in 1983, after switching from Yamaha to Honda. Hannah’s final national win came in the 250 outdoor national held in Millville, Minnesota, on August 11, 1985. He continued to race full-time until 1987 and then raced occasionally in nationals until retiring in 1989.
In his 15-year career, Hannah had become the all-time win leader in AMA motocross/Supercross history, having won 70 AMA nationals during his career That record would stand until broke Hannah’s overall win record in 1999.
Hannah continued to seek the adrenaline rush even after his motorcycle-racing career ended. After leaving motocross, Hannah took up the sport of airplane racing in the unlimited class. When inducted into the AMA Motorcycle Hall of Fame in 1999, Hannah was living near Boise, Idaho, running a sport aviation sales company and winery. In 2000, he was inducted into the Motorsports Hall of Fame of America.