My new (used) motorcycle backfires like crazy.

[dentheman]

I just got back from taking my 2007 Shadow 750 that I have had for 2 days for a little practice run around the neighborhood. I need the practice since this is my first motorcycle. All went fine until the engine warmed up fully, then it would backfire very loudly out the exhaust and lose power. Didn't matter if I was accelerating, decelerating, or cruising, and I felt lucky to make it home. I don't know where to start on this problem, any suggestions for a noob?