Type of Fuel to use
There is a difference between "Research Octane" and the octane listed at the pump (R + M)/2. The lower octane fuel burns easier and more completely. Premium fuel is only for engines that are designed to use it. The VN750 is not, so use regular 87 octane.
If you haven't noticed already, the fuel gauge will drop from half to empty much faster than from Full to half. I can get about 100 miles out of the first "half" and only about 50 out of the second "half". When I switched from premium to regular, I improved from 47 to 49 mpg. (I ride in a very "stately" manner). Also with regular gas, you have less chance of fouling the plugs and causing carbon build-up due to incomplete combustion.
There have been a few here that switched from higher octane to the more commonly used 87 octane. I have yet to hear of one that was not pleased with the results. If you have been running higher octane long you might consider cleaning out any residue from the usual build-up from the higher octane since it does not burn as efficently in our engines.