Loud bang and high RPM on start
So a little back story, I've had some electrical issues before which were fixed and I got about 70 miles of riding. Then one night my bike wouldn't catch and I ended up killing the battery after 15 attempts to start while rolling the throttle. I left for vacation for 2 weeks with the battery on a tender. I go and start the bike and I get it to start with the RPMs maxing out and a loud bang from right under my seat. This bang worried some of the neighbors and I didn't try to start it again. My best guess is that I've flooded either the carbs or the crank case. I've done some of the preliminary checks and everything checks out normal other than a weird mixture in my oil tank. So I'm guessing the fuel system is leaking into other things.
What are some checks that can be done to eliminate the carbs, petcock and how do I remove the extra gas from the engine block.
Thanks in advance !