My 2001 500 auto started missing and backfiring on a nasty section of a trail today,did it last week as well.I checked the fuel and the plug , both seem ok.Anyone else having any difficulty?
I drown this bike 65 miles ago but has run well since, shouldn't be related.

 

well with the change in temp, your jetting could be a little off. You could try the warm weather plug.
matty

 

Change your gas and drain your fuel bowl. If this don't help check your choke plunger and mixture screw.