My poor old 749S has been languishing in the shed un-ridden for about 4 years. My excuse is that it used to make my neck ache so I've been riding my old Triumphs. I have kept the battery charged and started it occasionally but it needs riding so I got it out ready for a wash and an MOT but it would only run on the vertical cylinder with the other one mis-firing.I took the plug out and cleaned it and then it wouldn't start at all! I had a look on here for advice and read all the relevant posts, I changed the annoyingly hidden relay even though I thought it was ok. Finally, front plug out again, connect up and it was sparking up in the body whatever I did to it. Found my old Champion plugs, cleaned up the best one, put it in and bingo! Both cylinders running ok after a bit of spluttereing from the vertical one. It is usually something simple and obvious. I should have checked the plug first but it hadn't done many miles. Belt change next!