So, story time.
I pulled the CB650 out to run some errands, and while I was out I filled up with gas. It’s about 3 miles from the FS station where I filled up to my home, and I came home without incident and parked the bike for about an hour. I was planning to ride it about 25 miles to see a customer, and so about an hour later I started it up and took off.
I went about another 3 miles or so, and the bike died like it ran out of fuel. I rolled into a driveway and tried to restart it, and while the bike was cranking good and hard it wouldn’t go. It really did sound like it was out of gas, so I flipped the petcock to reserve, and it started up after a very little bit of cranking.
I turned it back from reserve to “run” or whatever you call it, and rode back home and parked it without difficulty.
I’m guessing something plugged the upper end of the petcock tube, and flipping it to reserve and then back must have cleared it.