Wise guy remarks notwithstanding ( diesel and all that rot >
) I have a friend in the petrochemical business. He once asked what I ran in my motorcycles, and I told him premium. I forget now what started the conversation. I wanted to simplify the gas cans and such at the house at the time, and I picked premium. He remarked that that was a very good idea, skipping the octane part, due to the much improved additive package the more pricey fuel often has. Since I don't get 10-20 MPG with any of my motorcycles, I think the extra value is worth it to me. I'm also very close to sea level here, which makes quite a bit of difference. In colder weather (denser air= more O2 per volume unit of air), even my F150 pings on regular (87) under load in the mountains, so I tend to run at least 89 in it. And Ford specs 87 only in all of their vehicles.
Since Yamaha specs 91 minimum, I see no particularly good reason to second guess them, especially when I think premium is a good idea anyway. Mid summer, when the air is O2 deprived ( high humidity, less dense from the heat, etc) It probably doesn't matter as much. The O2 sensor resolves some of it, but not all of it, at least for my equipment. My WRR is very indignant if fed other grades than premium.
I know some of you mountain west riders don't have the same fuel grades available that we lowlanders do (can't call me a flatlander, as it isn't flat here) so you have to use what you have to use. I have the option, I choose premium.
Keep in mind I'm a sporadic rider: never commute, as I have to use the company vehicle. I don't ride intentionally in the rain or snow, nor when I'm fatigued. So the advantages to me for my fuel choices are less deposits, gummy gook and such during the times the bikes sit. I might feel differently if I rode every day, but due to a variety of things, I tend to be a weekend moto-goon for the most part. However, I often make up for the week on the weekend, so I suppose it evens out in the end. I had yesterday off, and the tenere went for a ride with our silly wind (30+ MPH with higher gusts) and today the WRR decided to go for a woods ride, and took me along. ::26::