Hi Kev, The slow and gentle tickover may be a clue…. I would try increasing the ignition advance to say 36 degrees before TDC on full advance, and see what difference that makes. As it is so very non-standard it is difficult to suggest other check points, but I see that you have changed the exhaust pipe and silencer from the system seen in the photo taken at Abbotsholme. If you still have it try changing back to that. Above all, only change ONE thing at a time, or you will never know what was/is the culprit.