Big-bore bolt-on kit increases your 114"/117" with 4.5" stroke M-Eight to 128" with no case machining required. 4 1/4" bore cylinders with 11:1 forged pistons. Wrinkle black finish cylinders with or without fin highlighting. S&S oil pump/cam plate with a blue anodized finish. Passage plugs are removable for servicing. Independent scavenge sections for flywheel cavity and cam chest. Debris screen in both scavenge pickups. Magnet in cam chest to help prevent debris from entering the oil pump. Increased oil flow capacity on both the oil feed and scavenge side. Adjustable pressure relief valve can be adjusted with the unit installed in the engine. Quickee pushrods with chrome pushrod tubes. S&S premium tappets. S&S hard-anodized, black-coated tappet cuffs are billet aluminum construction. Improve tappet stability in high-lift, high-rpm situations. S&S 550 cams designed for big bore applications. S&S valve springs; work with cams up to 0.605" lift. High-performance conical single-wire spring design. All necessary gaskets, bearings and hardware for bolt-on installation included. Made in the U.S.A.