I'm putting my neck on the line here.I think this is a 500cc Dommie,but as yet I'm not absolutely certain.If you know better,please tell me. see http://www.realclassic.co.uk/norton05031400.html see http://motorbike-search-engine.co.uk/classic_bikes/norton-dominator-gallery.php see http://classic-motorbikes.net/classified_ad.php?id=146