FUBAR
XS400 Addict
found these if you need a single
http://www.motorcycle-superstore.com/3/13/562/41526/ITEM/Mikuni-Carburetor-Mounting-Flange.aspx
http://www.motorcycle-superstore.com/3/13/562/41526/ITEM/Mikuni-Carburetor-Mounting-Flange.aspx