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.Shovelhead 1970-1983.