Backfiring

[mschap1992]

Hi, I began riding this summer on my 2002 gz250 and I love it. I then moved to the west coast of Canada with the bike. Since then, after I start the bike cold using the choke, attempt to reset the choke, and ride, the bike backfires when I shut the engine off. While I'm riding/idling at lights, it still sounds like the choke is in the same position it was when I started the bike, high revs, lots of fuel going to the engine. I took out the air filter as well and it stinks of fuel. Anyone know what I can do to fix the backfiring? Thanks a lot!