Evolution 83" Big Bore bolt on black cylinder kit Evolution 83" Big Bore bolt on black cylinder kit includes 10:1 compression Wiseco forged piston kit, which has been honed for final fitment. No case boring required. Kit has a front and rear domed piston. Cylinders are aluminum. Features cast in steel sleeve. Order top end gasket separately. Fits: FXST 1984-1998 FXR 1984-1994 FLST 1986-1998 FLT 1984-1998 FXD 1991-1998