All the Walbro WT carbs will interchange as far as mounting goes. An engine will run on just about any carb, but a 26cc likes a carb with an 11mm venturi. (The venturi is the smallest diameter in the throat of the carb.) Smaller than 11mm on that size engine will limit power. You also should use a free breathing muffler. You can buy or have a muffler made, or a lot of us just gut all the baffles, etc. out of a stock muffler, and weld in larger exit tubes. On a 26cc engine I usually use two exit tubes of about 1/2" or 9/16" diameter.

Another way to tell the size of Walbro carbs, is they have a number cast into the carb throat right near the choke area. That number is the venturi size in 64ths of an inch. For example if you see a "28" number cast into the throat, you know the following. 28 = 28/64" = .4375" = 11.1mm venturi.

One other very, very important thing. A lot of the newer carbs have only one adjustment needle. You definitely want a carb that has TWO adjustment needles; one for the low speed and one for the high.

AV8T0R