Tug, Please do yourself a favour and go and buy a copy of Vincent Motorcycles by Paul Richardson, as all the information you want is in there. This answer is not meant to be rude or short, but for the sake of a few pounds, a wealth of information can be had at your fingertips. This answer applies to many of the other Non Member technical enquiry postings on this forum. Respectfully, Phil Primmer, ET43.