Big enough...I tested 2 or 3 different carbs, from 3/8 to 1/2, not much difference..Walbro has a new small carb that seems to work really well..WT662-1..It has a 2 step choke, costs $38.80 retail...Only problem is the needles, they're both made with no slot for adjustment...A small cutting wheel on a Dremel fixes that...I tested one on a G26 with good results, same rpm as the larger stock carb....[8D]