BDL's chain drive features our "Competitor Clutch" for absolute transfer of power to the rear wheel. Our 7- plate Kevlar clutch provides at least 60% more clutch surface than stock. Our 9-spring pressure plate provides varying spring pressure needed for stock to strokers. Simply add or subtract springs for the proper tension on your bike. Chain drive kit for Big Twin electric start ( includes front sprocket, rear basket with "Competitor Clutch," Diamond primary chain & adjuster assembly).Shovelhead models 1970-1983.