My 06 grizzly sometimes back fires when I shut it off.
Is this normal?

 

No,backfiring is bad, and can possibly cause problems down the road if it gets bad enough. How is your idle speed? too high of idle will cause backfiring when shut down,also, is it running real hot? maybe hot enough to ignite leftover gas vapor in the intake or exhaust? Just taking shots in the dark, you could call a local dealer and see what they have to say.

 

My friends 660 did that, it turned out just to be a lose spark plug. The plug is very hard to reach so it may not be tighten down enough.

 

It's not a big loud back fire, it's more like a poof sound in the exhaust.

 

my grizzly does the same thing.
its normal.
the poof is jus left over gas igniting in the carberator.
its totally normal.