Anyone have have input on swapping the needle seat in one of these carbs? I have a leaky carb that new needles won't cure. I have a beat up spare carb with what looks like a good seat, but the rst of the carb is pretty much toast.
I would try dressing the old seat first. The seats are pressed in and very difficult to remove. Just take a Q Tip and pull the cotton off one end and wrap with a bit of 0000 steel wool. Insert into the seat and twirl with your fingers. Then take the other end of the Q tip and apply some toothpaste to it. Insert and do the same. This should burnish the seat and take out any small imperfections.
Examine the needle too. If the end is grooved, it probably needs replacing. And lastly, make sure the little spring in the needle end is operational. If not, soak the needle with carb cleaner and try working the spring until it works smoothly.
How are you determining that the float isn't working properly? Does fuel run out of the overflow? Or do you just feel the carb is flooding? Take a piece of clear tubing about a foot long and attach it to the overflow tit on the bottom of the bowl. Hold the tubing vertically along side the bowl and open the drain. The level should rise in the tube to slightly below the seam of the bowl and carb body. If it does go higher, you do have a float problem. If it doesn't, then maybe you have a split in the overflow tube. Not uncommon by the way. They are sometimes hard to see, but if you remove the bowl and fill it with fuel, and it leaks from the bottom, you have a split tube.
I think it is even possible to install the floats upside down. I can't remember what bike I was fooling with, but I got one in upside down. Didn't work well.
If you have swapped around a couple of needles, and dressed the seat, I'll bet that it is something else. I assume the floats "float"? I haven't heard of a case of sinking floats since they went away from the brass ones.