The ethanol has nothing to do with this, you know. Mowers set up with float-type carbs and gravity-feed are the most susceptible to this problem. When you store them, the fuel in the carb bowl evaporates and deteriorates, but it is constantly replenished from the fuel tank so that over the storage months, the carb bowl winds up acting as a distillation chamber and all the additives in the fuel precipitate out in the bowl and then clog the jet when you try to start the engine.
The best solution to prevent this is to put an in-line fuel cut-off in the mower's fuel line. When storing, turn off the cut-off and then run the engine until it stalls, this will suck all the fuel out of the carb bowl and prevent the varnish from forming. The bulk gas in the tank will *probably* last 6 months, but if it doesn't at least it hasn't wrecked the carb and you can just drain and refill the tank come spring.
The best solution to prevent this is to put an in-line fuel cut-off in the mower's fuel line. When storing, turn off the cut-off and then run the engine until it stalls, this will suck all the fuel out of the carb bowl and prevent the varnish from forming. The bulk gas in the tank will *probably* last 6 months, but if it doesn't at least it hasn't wrecked the carb and you can just drain and refill the tank come spring.