I just finished reading a good article discussing the factors involved in determining which grade of fuel to buy. I personally always contended that the higher the compression ratio, the higher the octane requirements. However, recent innovations with combustion chamber design have shown that even with a compression ratio of 11.5:1 - regular fuel can be used. The article also pointed out that for those of us (me included) who needlessly burn premium fuel, we might actually be getting less horsepower since the additives that make the fuel burn slower (higher octane burns slower to spread out the impulse to the piston over a longer period) have a lower heat value than straight gasoline. Food (or gasoline) for thought - I think I will switch to a middle grade. Now I'll stand back - - -

 

stand WAYYY BACK!!

 

I will be curious what you find out in your trials..........

 

My other bike is a Honda 1800 VTX and it runs far better on regular than premium. Using premium even dropped mileage by about 6 mpg. My Harley will ping on anything but premium. I think the Honda has multi spark ignition from factory and is far more efficent with it's computer programming. Try grades several tanks at a time and see if they ping. Use the lowest octane that does not ping.

 

I can say that I always burn premium. One time(in my 2004 carb model) I accidently put regular in it...and it popped and spuddered that day....never did it before...so my conclusion was.....that it was the lower octane.