According to the pilot, he was test flying the airplane after modifying the landing gear suspension. He stated that the takeoff was routine and that he stayed over the airport for about 30 to 45-minutes. He said he landed to the west and upon touchdown on the main wheels the airplane "deliberately" went to the left. He applied right rudder with no response and the right wing struck the ground and flipped the airplane completely over. He shut the airplane down, released his restraints and exited without injury. The pilot further stated that he had had two previous landing gear center bar failures and had reinforced the center tube to a larger diameter, and had tightened the lateral landing gear cables and safety wired them. He also reduced the spring tension from 6 to 5-turns which he stated was the wrong thing to do. He said that to fix the landing gear so that this would not happen again he would need to do chrome work on the center bar and replace all the landing gear cables with a larger size. According to the pilot damage to the airplane consisted of the right upper and lower wing, the left upper wing and the landing gear. In addition he stated that the parts that failed during the accident were the landing gear lateral cable and the spring windings. The pilot's recommendation to prevent this from happening again would be to have the airplane inspected by an FAA Inspector, and to do more taxi testing before flight.