more nubie mikuni carb info help!again

I got the 18mm carb,thanks for the help guys!another question I had was would a 16mm carb off of a 50cc pit bike work as well,the reason I am asking this is because the guy I got the 18mm from gave me 4 16mm carbs super cheap because he had no use for them they are from a 4 stroke sdg 50cc dirt/pitbke if that helps,just curious because now i have all these carbs and really only need one any info would be appreciated thanks.

the 16mm would work way better for a stock motor. like i said before, with a little porting and an expansion chamber, the 18mm will rip

thanks again,Ill try not to ask so many stupid questions,just want to build my MB right the first time.,