That is pretty neat actually. Are all your nuts and bolts still wired down? Anything I haven't taken off is. I figure what the heck might as well leave it. Won't ever have to worry about it falling off lol.
As far as the gas it has to do with detonation point do to compression. I know it has an aftermarket cam in it. It may have the timing advanced, I've never checked but this is my guess. The head may have been decked. It doesn't really look like it but then I've never side by side compared it next to another one. I've actually tried a few times to run 87 through it and it pings a bit and generally runs like crap. I actually dumped some of that crappy octane boost stuff in last time to try and help it out.
I can tell you I'm an auto tech by trade although I work in the medical industry now and I know all about grades of gas. I'd never waste my money on premium if it wasn't actually the only gas my bike likes.

 

Yup, all the nuts and bolts are still wired down. I guess that's a plus, but it does make the bike a bit heavier The only thing I know that was done to mine, is the wiring of bolts and manual cam chain tensioner. I wouldn't know anything else in the engine if I saw it, but it runs very nice. I haven't really noticed a difference in how mine runs between gas, maaaybe a little quicker with premium, but it could just be my imagination....kind of like the way one thinks his car runs better after an oil change. But I have been putting premium in lately. I figure even though gas is expensive, it's only a few gallons. In a couple weeks I'll fill up with regular and continue the process until I can tell a difference.

 

I couldn't read the entire thread, but I had a similar problem with my Magna. A cheap plug wire by the previous owner was actually shorting through the wire into the head. It caused an intermittent sputter and sometimes hard starts. (I fixed it with electrical tape....lol)
If a bike just suddenly has a problem, I never suspect bad gas, though. (and the F2 is fine with 87, btw).
Hell, I had a civic sitting for 5yrs with the same gas in it and it fired right up. I also had a jeep that sat for 6 months twice with no issues.
I've actually never had "bad" gas in any cars or bikes (except for on a trip once and it was obvious). Maybe I'm just lucky?
I do usually use seafoam as a stabilizer, though, fwiw. Just a couple ounces.

 

I believe you on the civic and jeep starting right up. Definitely. I've got a 1993 jeep wrangler with the classic, american designed and manufactured AMC 4.0 liter, straight 6. This engine has been used for years and years in countless models of cars, simply because it worked. It's one of the most reliable and durable engines ever made and I have never heard a spit or sputter from it. Been driving it for 7 years and has always fired right up even on the coldest of nebraska mornings. The engines in those hondas are fantastic pieces of engineering. The average person just can't appreciate all the details that go into designing the car they drive. The older volkswagens are the same way. Let it sit outside for years if you want, with the same gas and the f**ker will fire up almost instantly, if not in a few short cranks, that is, assuming the car and fuel filter hasn't been abused and neglected for years and years. So yeah, that makes one laugh at the idea of "bad gas". I guess motorcycles are just more sensitive.