After replacing the gas with fresh E0 and filling it up with almost a whole can of Seafoam, I warmed it up fully a couple times a week and revved it as much as it would let me. Until today, that meant it revved very little before dying. When closing up each day, rather than simply turning the key off, I would kill it by revving just in case that put more treated E0 where the clog happened to be.
It didn't seem to be getting any better. If I ever so slightly touched the throttle cables I could increase the revs but I couldn't hold it for long and pulling it slightly farther would always kill the motor. The idle speed adjustment would increase the speed up to a point but it would slow down after passing that point and I would always back off and return to something much closer to idle when it sounded like it was about to die. Shouldn't have because, as it turns out, that's exactly where I needed to keep it!
Today, I turned the idle speed up to the point where it would begin to die and left it right at that threshold. The speed would vary between faster and slower every few seconds but I noticed that the time it spent "faster" was increasing ever so slightly each time it went through this cycle. Gradually, it seemed to be working! The speed was fine (not racing) but I knew I couldn't just leave it like that because if it truly was working I could come back to find my bike ruined from being revved to the limiter and held there. Well, a watched pot never boils but I kept playing with it for what felt like an eternity (probably about 10 minutes in the hot sun), adding throttle until it would almost choke and then backing off until it settled into the fast/slow idle cycle again. I think my throttle application made it die a few times over the next 10 minutes but soon it was revving with no problem at all right up to the rev limiter!
We're clear.
I guess I really did have something in my carbs even though it revved fine so recently before that. I think my meddling probably loosened some tank gunk that got stuck which is why everything else seemed fine and I was able to clear it without a carb cleaning.