Carbs are lilely the most difficult part to modify, Like Simonizer posted, change the venturi and the fuel curve will change. This happens because the velocity of air going past the main feeder jet decreases while the velocity going past the low speed orifices near the throttle plate stay the same messing up the balance between low speed and high speed fuel. The result is often a lean mid range or an over rich top end.
Going in and messing with the orifices, mettering spring and trottle plate it is possible to get the fuel curve back but it usually takes some fiddling.
It is possible to get a little extra diamiter at the venturi on an 046 carb, but the passage up from the fuel pump to the needle valve is very close to the carb bore.
On an 046 work type saw there is no real need to go bigger on the carb, they will easily spin up 15,000 rpm without major changes. If racing than a bigger carb will be in order as there is just not enough meat on the 046 carb to work with.
If the bore of the carb is round without humps I will work them over on lathe, but sometimes work needs to be done by hand, 066 carb is one that has a hump near the main jet that makes lathe work impractical.
Cant remember if this is a 361 carb or 044/046. 044/046 I think, one on left bored out a couple mm. Have done some the full way trough making new choke and throttle plates, and relocating internal passages no easy task.
