See more: ENGINE GROUP - ENGINE PERFORMANCE KITS
128" Power Package Engine Performance KitBig Bore Kit Big-bore bolt-on kit increases 114"/117" with 4-1/2" stroke M-Eight to 128" with no case machining required 4-1/4" bore cylinders with 11:1 forged pistons Oil Pump/Cam Plate S&S oil pump/cam plate with 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 Pushrods Quikee pushrods with chrome pushrod tubes Tappets S&S premium tappets Tappet Cuffs S&S hard-anodized, black coated tappet cuffs are billet aluminum construction Improve tappet stability in high-lift, high-rpm situations Cam S&S 550 cams designed for big bore applications Valve Springs S&S valve springs work with cams up to .605" lift High-performance conical single-wire spring design All necessary gaskets, bearings and hardware for bolt-on installation is included Made in the U.S.A. Not recommended for Tri-Glide or other three wheel models including conversion due to lugging nature of these bikes.