Not startinging after replacing the piston and cylinder head

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

I was out riding and during the ride my spark plug came out and then I heard a popping noise and when I got it home I popped a piston ring and the cylinder head was scratched so I replaced the cylinder head and piston and rings and when I installed the new piston I took it to the top of the stroke and torque the head down and now I can't get the engine to start if any one can help me with this I sure could use it.

I replaced it with the same size and when I reconnected it I took it to the top of the stroke and torque it to spec about 14foot pounds and I got good spark and the clutch is set right but I still for some reason I just can't get it restarted and it doesn't make since.