stomp pit bike

i have replaced all my wiring including the cdi coil kill switch and spark plug even the stator but I still have no spark

I have just put another piston and rings in my pit bike it lost compression I have got it started but it runs really rough I have double checked the timing and cleaned the carb a couple times but still spluttering and boggy and back firing

Hi guys, new on this forum as i was getting no where on pbc. the issue i have is, i've just been out and bought a 2011 stomp 140 that i presume has the YX engine in, as the engine number is 1p56fmj which i googled. the lad a got if off clearly new nothing about bikes.... So i got it in...