Boogieman wrote on 07/22/13 at 15:30:10:

You need to do a little looking and reading on your own, and save us for those things that can't be found on Google!

Google MTBE.....and you will have your answer in seconds.

On a volume basis - per gallon - propane has about 10% less energy than gasoline. The Air Force played with it in the late 70's during one or another of the fuel crunches. Measured in miles per gallon propane comes up about 10% short. And it requires pressure tanks where gasoline is liquid at ordinary temperatures.

E-85 is 85% ethanol and 15% gasoline. Consumer Reports had a couple of articles on it a while back, and you can look them up for your information.

Ethanol is the same stuff as drinkin' alcohol. In order to avoid paying high Federal alcohol taxes it has to be denatured, or made undrinkable. For use as fuel, it is usually denatured with about 10% unleaded gasoline, which can be separated from the ethanol only with great difficulty. This 90% ethanol/10% gasoline is then added to gasoline to produce E-10 fuel.

As long as a gaseous mixture of fuel and air, in the proper proportions, can be delivered the internal combustion engine doesn't care much what it burns. There may be problems with knocking, but anything from hydrogen to motor oil will run an engine. Heavier oils will require heated intakes to vaporize, but old-timers may remember tractors which started on gasoline and were switched to kerosene or "tractor fuel" once warmed up. Alcohols are just another fuel.

Dave remarked that E-85 can only be used in Flex-Fuel vehicles. This is true, if the vehicle also has to burn "pure gas" or E-10. Those vehicles supposedly have fuel systems that can handle the alcohol and computers "smart" enough to adjust the mixture as needed for anything from no ethanol at all to 85% ethanol. But if you wanted to use E-85 as the only fuel a reasonably simple carburetor rejet would do the trick.

Many light airplanes have carburetors with a mixture adjust control. This is because as airplanes climb the surrounding air becomes less dense and the mixture becomes richer. The mixture adjust allows the pilot to adjust the mixture as needed. It might be possible to adapt such a carburetor for a motorcycle, perhaps marking the mixture control for E-85, E-15, E-10, or no ethanol. Just think - another control to play with while you ride.