Correct me if I'm wrong - bolt is M8 and I believe the thread pitch to be 1.25, same as Triumph Speed Triple.
Anyone try a non-RE bobbin? I'd like to try the Oxford Spinners but I suspect there's not enough clearance as the mounts are recessed by a couple of mm behind the swingarm. The RE bobbins have quite a large offset (Roshiba777's pic below)