John Larson began his career in motorsports as a drag racer in the 1950s. While working for “Speedy” Bill Smith at Speedway Motors in Lincoln, he got his first taste of dirt track racing, becoming a member of the team that built the successful No. 4X Sedan driven by Lloyd Beckman. Larson eventually opened a performance engine building business, Larson Racing Engines, in Lincoln and formed a successful Sprint Car racing team, with a number of drivers, including J.J. Riggins spending time in the cockpit. Over the years, his engine building business built power plants for some of the most successful dirt track drivers in the Midwest including Late Model pilots Clayton Petersen Jr., Rex Nun and Dan Rabbas.