More than 30 of the best Supermoto riders in the West and 100 of the nation’s best shifter kart racers will invade Infineon Raceway for the 3nd annual KartSport Grand Prix/Supermoto USA Invitational, presented by Jim Russell Racing Schools. This event, which is hosted by KartSport Magazine, boasts a $19,000 purse — one of the largest in the action sports industry.