Complex sentence: Mann turned expert in 1955, and finished seventh on a Harley Davidson in his first Grand National race, the Daytona 200, back went it was competed on the Daytona Beach Road Course.
Split into simpler sentences: Mann turned expert in 1955, and finished seventh on a Harley Davidson in his first Grand National race, the Daytona 200. At this time it was competed on the Daytona Beach Road Course.