I have an MZ 301 ETZ with a Bing 84 carb and although it used to start with the cold start open it does not want to do so now. I can start the bike by operating the cold start and operating the kick starter a couple of times and then closing the cold start and then opening the throttle and operating the kick start a few times when it fires up. Before I take the carb off to investigate does anyone have any idea what the problem may be. I suspect the cold start jet may be blocked but would welcome any suggestions.