Twin Power is proud to offer a line of high quality USA made valve and spring kits. Offered as Black Diamond Valve kits or Complete Valve and Spring Kits. Valve kits include 4 stock size Black Diamond valves for each application. Engine kits include 4 stock size Black Diamond valves, a complete O.E.M. replacement spring kit, steel retainers and keepers, and valve guide seals where applicable. Black Diamond Stainless steel valves are impregnated by a special German process to a depth of .002", with a surface buildup of .0002". This Black Diamond process improves wear properties, reduces friction and provides resistance to corrosion. Valves are lightweight, strong, one-piece forgings with profiles that provide excellent flow characteristics. Spring kits are O.E.M. type replacement kits, designed to give stock pressures and work with stock cam profiles. These kits are manufactured to original O.E.M. specs using premium modern materials, design protocols and manufacturing techniques. All components are high quality parts. Valve Springs are wound from super-clean chrome, silicon valve spring wire that has been heat treated and shot peened. The retainers, keepers, and bases are designed to provide maximum mechanical strength. Beehive style springs are supplied where applicable. Valve guide seals are red 100% Viton valve stem seals. Designed to have optimum fitment, allow maximum lift and maximum life. Resistant to high temperatures.; ; Note: Late shovel kits include a stock type "K" line seal. Knucklehead and Ironhead Sportsters do not include seals.