In all my 1330's (three now), I get on average high 30's in all three. A couple of times....low 40's. I check almost every tankful.

I do not use the mpg stuff the bike puts out. I zero the trip meter at each fill up, fill to the same level each time, and divide miles driven on the tank by gallons to fill. I use 87 with 10% ethanol. I have been using low octane for many years now and have noticed NO difference in operation or mileage when I quit using premium. About 2015.

Also had 4 998's. Always used premium in them. Mileage was in the low 30's. About 10 mpg lower than the 1330's.

There have been a few threads about low octane vs. premium, performance vs. mileage. All are interesting reads. My bottom line is printed above.