Weird vacuum problem with gas

I filled my bike up and i rode it home. Then it sat for an hour. I filled it up on the sidestand on level ground and parked it on level ground. When i came outside a little gas leaked of the vents not the overflow. Then gas leaked out of the gas cap. I have a non vac petcock. I am not sure if these things are linked together. It started like a week ago. There is no gas in the oil. Thanks

 

How far did you ride from the gas station to home? When gas comes out of under ground tanks it's cold and takes up less room. Now when the gas warms up in the tank it can expand and leak out.

 

That's exactly what happened.

 

How full did you fill it?
How hot was it outside?
Combine an overfilled tank with a hot day, and a blocked tank vent, and you get pressurized fuel finding its way past the gas cap seals.
Clean the cap vent, and maybe replace the seal. http://www.xjbikes.com/forums/posts/472172/
Don't fill past the bottom of the neck in the tank. The airspace above is meant to allow for expansion. I do sometimes "burp" the tank when I fill it to get a few more ounces of fuel in, but only if I'm planning on using that extra gas right away (as in not stopping again until I hit reserve).

 

It was less than .5 miles home and was like 80 degrees fareheit. I did fill a little pass the neck. So would that cause the gas to come out of the breather on the carb (xj700).

 

Potentially, but that's more likely a bit of crud getting stuck under the float needle, or a float sticking, causing the floatbowls to overflow.