Stock bore stroker kits have always been an economical way to increase the displacement of your engine. This S&S 84" stock bore Hot Set Up Kit upgrades 74" knucklehead and panhead engines to 84" displacement at approximately 8.4:1 or 7.3:1 compression.Includes a dynamically balanced 4-1/2" stroke flywheel assembly complete with S&S heavy duty connecting rods and mainshafts. Stock bore stroker kits reuse the stock cylinders, saving cost and retaining stock appearance of the engine. Minor crankcase and cylinder modifications are required, that can easily be done with hand tools. This kit requires special pistons which must be ordered separately depending on the oversize required for the stock cylinders. Piston type determines compression ratio.