3-1/2" Bore Cylinders for 1984-'99 Big Twins with stock, S&S® Performance, or Super Stock® Heads - Natural3 1 2" bore cylinders for Stock, S&S Performance, and Super Stock Heads. 1984'99 big twins. On top of being constructed from superior materials, S&S replacement cylinders have thicker castings, larger cooling fins, and better wear resistance than stock cylinders. Super Stock pistons for 80" engines can be used with stock 80" flywheels without rebalancing. Individual cylinders and cylinder sets without pistons are bored slightly under normal size and