Dude... all this time it was just a bad f*(king tank of gas -- I think some condensation got in there, somehow, even after filling the tank to the brim. It was the tank I filled from last October, and I've never had to put Stabil or anything in either tank before (the Hayabusa started right up and ran great). Granted, I put 87 in the SV and 93 in the Hayabusa, but 87 is what the manual calls for in the SV -- and they were both in my dining room all winter, so it's not like they were getting thermal cycles. So, after buying $60 worth of ratchet extensions and $15 worth of spark plugs that I didn't need after all (but it's got new plugs now -- bonus), I put 2 gallons of 93 in the tank along with some fuel injector cleaner and it's been running fine since, as the 'old gas' burns off. I knew what bad gas felt like on the Hayabusa, but not in the vtwin bike, but I suppose the symptoms were similar... the Hayabusa just took it a lot better than the twin.