S&S has been building big bore kits since the 60s and has it down to an absolute science. Their latest efforts are aimed at the Milwaukee Eight® platform (2017 and newer big twins) and open up a whole new level of performance for these engines. Combining a new design forged piston with their 4.25" cylinders to net a tire melting 131 cubic inches when paired with their 4.625" stroker crank. We build our big bore kits and cranks to much tighter tolerarances and with higher quality materials than the factory parts. This new piston/cylinder kit will be a solid platform for massive power.