Just a request for clarification. A guy I was chatting with the other day (he's manager of a local Honda dealership) warned me against using my good old Stanley hex keys on my Sportster because he said "Harleys use Whitworth sizes not English Imperial". Now I thought that Whitworth was a term applied to the threaded part of the fastener and not the head but I would value any of your views on this if I'm wrong coz I really don't want to damage a fastener. Wikipedia doesn't contradict my current understanding as far as I have read it. Thanks folks.