carburettor differences??

Hi hers. I have a dello 38 on my kati and somehow the constantly probs. from the overflow hose constantly drips out a liquid, but that doesn’t seem to be just sprite. anyway it smells a little spritey, but feels greasy and is quite clear. is the condensation water? the carburettor I already let run empty, and it was cleaned only recently. how else can it accumulate fluid? my plan was now to find another carburettor and now the question comes up. what is the difference between the 38 and maybe the 40? can I simply replace or adapt the one that doesn’t and how does that look like with the consumption and the power. does that change what? thanks to many in advance. until then g.