Lectron only sells like 30mm+ carbs I think
Smartcarb sells a 25mm and 28mm and will pretune it for your moped if you give them your setup and previous carb tuning. -$500
Treats sells adjustable main jets for tm24 and vm20/22 for a lot less.
I use both a 25mm smartcarb and adjustable tm24 and they both work fantastic. My personal favorite options for mopeds. You could probably make slightly more power if you tuned a pwk just absolutely perfect, but the smart carb just smooths everything out and is easy. Tm24 is tm24. You can have sloppy tunning and spitting gas out the front but it always runs great!
25mm smart carb on 70cc stage6 Hobbit
TM24 on 76cc stroker case inducted eurokit E50 (edited)