If the bike is designed to run on 87 octane then run 87. If a vehicle is designed to run with a higher octane, using a lower octane may result in pinging but more likely the EFI will retarded the ignition just enough to avoid pinging. The result is degraded performance as the throttle calls for more acceleration the EFI computer is attempting to slow the rate of acceleration. This wastes gas. Using the proper octane in vehicles that require the higher octane will deliver a slight increase in mpg that will more than offset the increased cost per gallon.
For example, my Goldwing requires 91 octane per the owners manual. It will run adequately on 87 octane. The mileage on 87 octane averages 42 mpg on the highway. Filling the tank with the recommended 91 octane will increase the mileage to nearly 46 mpg. The cost per mile is better with the higher cost gas so going cheap at the pump is detrimental in the long run. You bike is designed to run on 87 octane. The above increase in mileage will not be realized as the EFI computer is not trying to process conflicting inputs, it's running normally. Running 91 octane will result in unburned gas being pushed out the exhaust wasting gas and decreasing the mpg.
04 GL1800A - Traxxion suspension
11 DL650 ABS white - Lowered, Risers, Richland Rick stuff, Sgt seat, Madstad