Never heard of it..............It happens all the time. Bike was ridden about two weeks ago, but only for very little time to test ride when got the bike. Have not checked the plug yet will do. It will start when you pull it with something. I don't know about the valve clearance, but when bike does run it back firers when you press the throttle fast and some times shoots flame out the back but, only when giving it gas.
What is your opinion on the new E3 Spark Plug?