Concerning the octane rating of fuel that we use in Electronic Fuel Injection (EFI) motorcycles that have a computerized engine control, I think we can take some guidance from the automobile manufacturers.
I have two Volkswagens. The owner's manual for the one that has a 12 cylinder, 450 HP engine recommends premium grade fuel, but notes that the car will perform satisfactorily with regular grade fuel. The owner manual notes that the engine won't make full rated horsepower using regular grade. The owner's manual for the other one, which has a turbocharged 4 cylinder engine, mandates premium fuel. The owner manual notes that regular grade fuel can be used in an emergency when premium fuel is not available.
I'm quite familiar with the 12 cylinder engine design and engine control system. The engine has 4 knock sensors, and if knock is detected, timing is changed until the knock stops. My guess is that if regular fuel is put in the car, it just adjusts the timing accordingly, hence the reduction in horsepower available.
Given that Honda is recommending, rather than mandating, premium fuel for our motos, I think that implies that no harm will be done if regular grade fuel is used. I suspect that engine power output is diminished when regular fuel is used.
Where I live (Canada), the price difference between regular and premium is about 6%. Although I like to save money as much as anyone else, I think it is incongruous to make a discretionary purchase such as a sport-touring motorcycle or a 12 cylinder car, then give up the performance we paid tens of thousands of dollars to get in order to save $2 on a fill-up.
I could understand the desire to save a few cents on every fill-up if this was a discussion forum for Yugo cars, or cheap Chinese 150 cc bikes, but I can't see the point of trading off performance for such a small dollar saving in a forum where the price of admission is a $17,000 moto.
As for that ethanol crap... I read an article in the WSJ last week that stated that the USA was soon going to be second only to Saudi Arabia in domestic oil production, this a result of all the shale oil getting pumped out of the Bakken formation. Why the heck is the government in the USA still permitting gasoline to be adulterated with ethanol? The days of Arab oil embargoes are long gone. Shouldn't that ethanol crap be outlawed now?
Michael
) It's been 10 cents a gallon more than 87 forever. Last night I pull into a Sunoco and the 89 is 20 cents more than the 87,never mind the premium at 50 cents higher. 
