Dave wrote on 05/14/12 at 04:18:42:Fuel with 10% ethanol runs just a tad leaner than pure gasoline. So the combination of being jetted by the factory to run lean and clean...along with the leaner burning ethanol mix.....means that your engine is running pretty lean. When you run pure gasoline the mixture gets a little closer to the ratio the engine would like to have to run well. Cars with fuel injection and oxygen sensors can adjust the fuel/air mixture to work well with any combination of gasoline and ethanal that comes from the pumps - engines with carbs are not that sophisticated.
Unfortunately it is a real "treasure hunt" around the Northern Kentucky/Cincinnati area to find gasoline that is not blessed with ethanol. I have to drive to Liberty, Indiana and go to the CountryMark to buy 90+ gasoline that is not mixed with ethanol. I take a trailer and a 55 gallon drum or two and stock up. I use this gasoline in my bikes and lawn equipment and I no longer have problems with corrosion in the fuel system or dissolving fuel lines.
I agree with your analysis ... and raise you...
Not only is Ethanol, providing a leaner mixture to our bikes... BUT because I live in Mississippi.. humidity often runs 100%.. thus the Ethanol is sucking moisture out of the air fairly dramtically. I truley think that is a large part of our problem down here, large amounts of water mixed in the gas.