I just finished a rejet and put everything back together, and went to turn the valve on the tank to on, and nothing happens.  A few drips will come out, but then nothing.  I narrowed it down to the tank valve, cause I only have a hose connected to it, and I turn the valve, and nothing happens.  What could be wrong?
When it was all hooked up, I put it on prime, and no fuel flowed to the float bowls.  This is why I started testing at different stages, and it went all the way back to the valve on the tank.  In any position, it just doesn't let fuel out.  I think I have enough fuel, it's over 1/3 of a tank.  Any thoughts?

Which hose from the tank, you may be below the regular pickup and is onto the reserve  pick up. Have you made sure that the tank petcock is open, you need to make sure that the cutout line points straight up and down, past this in either way cut flow significantly .

Yep ... what HE said. 

Check out [THIS OLD POST] to see how I performed a similar test ... and at the same time "proved" which outlet from the tank petcock was which.

Yep, that was it.  I guess my prime position has never worked.  The previous owner had switched the lines connected to the tank.  I clearly marked everything so I could put it back together, so I know it was how it was when I disconnected everything.  So the whole time I've had the bike, it's been run through the reserve part of the tank without me knowing it.  Good thing I never ran out of gas.  It's interesting that the prime didn't work when they are switched.  Thanks for your help.

I accidentally switched my lines last time I had the tank off and didn't find out until I ran out of gas (Luckily I was so close to the next gas station, I coasted in).  However, my petcock still allows fuel to flow freely into the carbs in the prime position.  I know because after reversing the lines, I had to drain the float bowls and allow fresh fuel to flow into them.  The flow would stop when setting it to ON. 

I haven't switched them back yet.  I just use the ON position as my reserve.

Does your petcock work properly in both ON and Reserve now?

BH