True ethanol hater here. I had to replace the bowl gasket every three months on my 147 because of ethanol. When non-ethanol became available I switched and have not replaced one in five or six years. My 129 has never had a carb issue and I run nothing but ethanol free. My small engine shops here also state do not use ethanol in your small engines. I bought a log splitter that had run ethanol for several years and the inside of the carb was completely destroyed. Ethanol is bad juju in your small engines especially if they sit around a lot. P.S. Stabil is your friend.
I now have the rebuild kit and Tygon fuel line for my Cub. I agree with the idea of using non ethanol gasoline. I keep a five gallon translucent dirt bike fuel can of it on hand for the Cub and a older Troy Bilt tiller with a Magnum 8HP Kohler. I still use a fuel stabilizer as from what I read, unless it’s AV fuel, gasoline goes bad within 6-8 months without a stabilizer. I’m not a fuel expert, but the black residue in my carb, had to come from that black fuel line. The sediment bulb bowl and the fuel tank are a clean as it gets
Two things you might want to consider Gasoline formula changes winter blend, summer blend. Ask a fuel driver in your area when they switch, I like the winter blend. Also 360 marine grade stabil helps with the condensation in the vapor space of your tank as well. Witch here in Ga. The humidity gets pretty high.