What's my Carb size?

[BuiltDiesel]

I need help figuring out what my carb size is. 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. 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 get a new one. This one is just giving me too many problems.

 

[BuiltDiesel]

Pictures can be found here imgur: the simple 404 page

 

[AntNZ]

Pictures can be found here imgur: the simple 404 page

never had one of those engines but apparently the oko 26mm flatslide carb go great on them and are really easy to tune.
Cheap Dirt Bikes & Thumpstar Parts For Sale Online in Sydney have them for $120 i think.

someone correct me if this carb is too big........

 

[gottagetacheaperhobby]

I had a 26mm on my gpx125 and it ran fine, but some do recommend a 24mm.

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