What’s the difference between these carburetors?

Hello, I wanted to buy my Race gt 50 a nine carburetor because the old one is for the ass and runs too thick. As if I fluctuated between these:https://amzn.to/2OEHc9I (the “normal” 12mm orhttps://amzn.to/39llfUY (the tuined) 18mm I don’t know about carburetors, so I ask misch what is the difference between the 12 and the 18 mm carburetor works the bigger one at all on my standard engine and the specified 80 so 6mm by let too big for my Moto r if he already has problems with the series carburettor, but I have to say that I don’t know if it’s another nozzle because my scooter has been stuttering suddenly.