Hello i´m new to the forum never new thier was one. I´ve owned bsa for the past 5 or 6 years now. Just a couple notes to add on to the above column writin by David when grinding the crank journals they also (NEED) to make sure that the edges maintian a 125 degree radei and also when the crank does get turned to also make sure you check the big end jounal. Not only can are thier different sizes of big end bearings but also their are 4 different bushing set ups that are used. Okay i´m sorry to bore pun intended, You can obtian a copy of the factory manual from most any british shop and will give you a good idea of just what you´re in for. GOOD LUCK you´re gona need it oh and if you do get one PLEASE don´t be a dick and hard tai it and -hit treat it with the respect that the bike deserves.