RE: Walbro carb model number deciphering (GX25)
I'm not sure if all 4-stroke carbs operate the same. That's what the Walbro tech told me and I've never seen a pump diaphram spring in a carb except on this engine. I am considering T-ing the crancase vent and using one of the sides to operate a +presure 2-stroke carb that way there would be unlimited possibilities. I was told that a WT456 carb would work and had double needles, which it does, just haven't got around to making an adapter carb spacer as the pressure holes aren't the same pattern.