So in the space of one week I went from an occasional pop to pop pop pop popopopoppoopopop everytime I engine break.  I don't know what changed or what to look for.  The bike does have a vance and hines full system- but for 6 months the jetting seemed perfect.

Plugs are new - old plugs looked fine and were tan in color.  Valves are good.  Air Filter is clean.  blah blah blah-  like I said, nothing has been changed on the bike but all the sudden it's back firing like mad.  

Thanks for the help.

Look for leaks in your exhaust system.

Or intake manifold or air box hose come off or pinched some or other hose. You have just gone slightly lean for apparently no reason at all... and all of this contributes.
Cool.
Srinath.

Quote from: Hi-Tnothing has been changed on the bike but all the sudden it's back firing like mad.

NOTHING has been changed?  You didn't need to swap out any shims when you checked your clearances recently?

Ok -My bad...

The back firing started before I checked the valve shims.  When I checked,  three were slightly too tight- but they are all good now.  The bike pulls a little harder now but the backfiring is still there.  Not worse, not better.

Thanks again for the tool Kerry-