Hi, I was out on my ride when the spark plug vibrated loose and came out and when it did I heard a popping noise and after tearing it apart I blew a piston ring and had to replace the cylinder body and piston it won't start. When installing the new parts I took the crankshaft to the top of the stroke and for some reason I can't get it started so my question is why won't it start. Any help that I can get would help