Battery connected Backwards

Hey everyone, i had battery off and charging, wife put it on while i was at work.She put wires on wrong side. She said it would just hum when she pressed starter. I fixed the wires and now I have an atv that misses, spits and sputters and backfires when you give it the gas. Its a 96' Polaris 425 magnum. What electrical damage could this do? any help appreciated??????
Thanks, GH

Its possible it could have damaged the stator or the rectifier.Not real sure how to tell to check them on a polaris though