While not a RT but a "C" I dropped the octane down to 87 and my mileage increased.
I have a mixed commute of 110 rt daily. Half is 35-50 and the remainder 70+MPH.
I get on avg. 42-45... My best was 66 mpg when I kept it under 60.
Yes, it's a cruiser not an RT.
I'm chiming in because octane can and will have an effect.
I've been running 87 for four years now w/ no ill effect.
Try it.
Do about three tanks for the system to adjust.
Wow, interesting. A tag under the seat suggests octane of 95. That must be European numbers cause we don't have that here unless you buy avgas. So at Shell I buy 91, or super, thinking thats what I need. Midgrade is 89 and low is 87.
I did change my plugs to Autolite. Lots of folks state the bike runs smoother with them. Any chance Autolites give poor fuel econ? The bike sounds and runs great. I can't imagine spark plugs can make that much difference? The Bosch plugs are twin tip, Autolites single.
I'll try the 87 for a few tanks and 89 for a few. 91 is too expensive anyway.