What's wrong with my carb?

I need help figuring out what my carb size is or what's wrong with it. I got a 2006 gpx 125cc motor from a 2006 Pitster Pro swapped into a 2011 Pitster Pro frame. It ran fine for a while until about a week ago. I was riding on some trails. Nothing serious. But on the way home, it started backfiring and bogging down when I gave it throttle. I got it home and just set it until today when I decided to try and figure it out. It runs and rides fine but the problem is it will not let me go full throttle without dying and it start sputtering. If I give it full throttle, it starts dying, bogging down and backfiring. Even in neutral, if I full throttle, it backfires and boggs. I've had problems with this carb before, the overflow is always dripping and the idle is all over the place Can you help me figure out the carb size? I'm just looking to fix and clean this one, or get a new one. This one is just giving me too many problems. I was told it could be the fuel air mixture but I want to see if you got any other ideas of what it could be.