This is a set of 4 84mm Wiseco forged performance pistons for a gen 2 1340 hayabusa.13.5:1 cr. the kit consists of 4 pistons, 4 sets piston rings, 4 wiseco gudgeon pins and 8 wiseco circlips. we also stock all sizes of cometic head and base gaskets for you hayabusa, call for details on these and other sizes,compression ratios available for all years of hayabusa. your one stop Busa Shop!