Oil / GAS leaking into the air filter?

ok, so my bike is Garaged at the moment, I was driving on the freeway and my whole exhaust pipe disconnected from the bolt and detached from the header. I drove like this for a good 15 minutes after.

When I stopped, I noticed ALOT of oil (at least I thought it was oil) pouring out of the header. I drove it like that home (IT WAS LOUD!) and garaged it and its been garaged since. It was also leaking oil from the middle, it seemed like it was coming from the air filter box.

I removed the seat, I removed the gas tank, took the funnel off the top of the air filter box, took the filter out (which was oily) and the bottom of the box had what looks to be oil and gas.

What could be causing this?

I have been using unleaded 89 but I saw on the battery panel it said it required 91, could this of done this?

Any input would be amazing guys, thank you.

 

Oil and gas coming out of the air box is usually from gas getting into the crankcase. The gas gets in the crankcase from a combination of faulty parts or adjustments.

-Petcock left on prime
-Petcock not shutting off when engine is off
-Float levels set too high
-Float valve stuck open or leaking

Here's only one link to many reported similar problem....
http://www.xjbikes.com/Forums/viewtopic/t=13916.html

 

You left out -Horribly overfilled crankcase. PO had a full GALLON of oil in my '83 when I got it.