S&S 106 in. Big Bore Black Kit for Harley Davidson 2006-13 FXD, 2007-13 Big Twi No need to bore or split the cases, just swap out the cylinders Superior cylinder liner material over stock, drag and dyno tested 3.927in. bore, 4-3/8in. stroke, 10:1 CR on stock heads, 9.7:1 CR on S&amp;S 89cc heads Available in silver or black wrinkle powder-coated cylinder finish