Gas in the oil

The last two days when I would go into my garage I smelled gas. I didn't think too much about it, it's a garage. When I started my bike, gas poured out of the crankcase vent tube. Now, I have a habit of turning the fuel valve off and letting the bike run out of fuel so there's nothing in the bowl, and it's a new valve as well. I looked in my gas tank and it was almost empty. I checked my oil and it was so mixed with gas there was no oil film on the dipstick. I drained the oil/gas out of the tank. I'm like, how the hell did all that gas drain thru a new, closed petcock, past the carb inlet needle and seat into the crankcase? Incidentally, its a 71 sportster with a 38mm Mikuni carb. I'm going to check the fuel bowl tonight to see if it's re-filled. Any ideas, feel free. Joe

Disconnect the fuel line from the carb and put the line in a jug,turn the petcock to the on position, then turn it off to see if it is really closing. The only way for it to overfill the carb and wash down the engine is if it flows past the petcock. There could be a little crap stuck in the petcock not allowing it to fully shut off.
Drain the oil and put fresh oil in, I would even consider pouring some down the spark plug holes to and turn the engine over a few times by hand, then do a quick oil change again.:devil:

Right after I posted, I removed the drain plug on the carb bowl and placed a small tomato sauce can under it. It's about 4 hours later now and no fuel in the can with the petcock off. The tank was just recently cleaned out and re-sealed, the carb was dissassembled and cleaned and a new petcock was installed. Tomorrow I"ll take the bowl off the carb and pour some gas into it and see if the floats rise.