Engine idles, wont rev up

So I bought an 82 kz750 csr the other day and Ive been tinkering with it. It started fine this morning, but then i stalled it out trying to get up the ramp out of my garage. Since then, if I try and give it some throttle, it seems like it clanks and bogs down and turns off hard. BANG! Did I screw up the bike? Any ideas as to what this could be would be appreciated.

well the first question was it running ok before you tinkerd with it?? and what did you do to the bike

turns out, it was just the battery. completely dead. I was a little scared.