My bike started to slowly lose power till the engine died, over about 6 or 7 blocks. I was pretty pissed, since I had just had the carbs cleaned and a new rectifier installed a month ago. Charging system was right up to snuff after the rectifier install, stator was fine also. Anyways, after letting the bike sit after pulling off the street, I was able to start it again and ride the 6 or 7 blocks home. I figured it was the $20 rectifier I got from china, so I bought another one on ebay. The next day, I checked the wiring and rectifier, looked fine, nothing was getting too hot. Couldn't check the electrical system, I don't have a meter, but battery did not seem comprimised. Looked in the tank and it seem very low for not using reserve. I try to keep the tank at least 40 percent full, because I NEVER use reserve unless my life depends on it. This is one way carbs get clogged. I've included a video so you can see where the gas was at just after the engine cut out. But we need to find out why I was able to start the bike after sitting to rule out electrical issues. I do know that if you start the F2 without turning the gas on, you can ride damn near a mile before you notice anything's wrong. Link below:

 

the gas in the tank both looks clean and the filter isn't clogged. Could be the diaphragm in the fuel tap. Normally, the reserve only uses the last 7/10s of a gallon. The tank holds 4 gallons total with about 3 and 1/2 gallons on the main tap. You can pull the vac line off of cylinder #1, plug the fitting, and suck on the end of the vac line to let gas flow. You can use a vac pump or gauge too. If the diaphragm is failing it will not hold a vac or you may taste gasoline, so be careful if you use the mouth method. I use this method to drain my tank when I remove it to work on my f2.

 

If the petcock screen, and its sealing O-ring, are intact, then using "Reserve" is nothing to worry about... read this posting I made a couple of days ago:

Petcock Reserve Setting Myth