Cylinder Head and Base Gasket Kits for 124" and 128", oil-cooled or water-cooled models, with 4.25" Big Bore Cylinders. This is a strictly bolt-on kit, as the special gaskets eliminate the need to weld and modify oil or water passages. Gasket kits are available with either .030" or .040" thick gaskets . The Cylinders are offered in a factory-style black texture finish with highlighted fins. Cast-iron liners ensure strength, durability and quiet operation.