Great Mr dooley you've found another answer.
I'll add this to the TEV valve technical.

so here we have it,

Backfire... shorten the spring
Dieing at stop... lengthen it.

I've got the backfires real bad, and my bike stumbles on decel. You can hear it try and catch back up after you stop, kinda like catching its breath.

While I was working on my bike tonight I decided to take step one and "clean" (ha! i just shot carb cleaner around there...) the TEV to see if anything improves. I did notice gas sitting in there though. It was collected on the brass dish that holds the spring on the diaphragm. I'm guessing either that is normal or my TEV is too rich...

i talked to a buddy of mine... he said it is a combo of things, first being carb not metered and jetted properly... second the pilot air in the carb bowl needs to be upsized..... about 62.5.... and the pilot air in the slide diaphragm needs to be upsized.... no more backfire...

The Volusia website states a 1/4" washer but I used a washer with a 5/16" ID and 11/16" OD and it fit perfect into the TEV housing. I had already converted to a .66" diaphragm spacer and backed out the idle air mixture 1/2" turn. I am running a stock exhaust and intake filter.

ah yes, tuning fun  

Tom Dooley wrote on 10/20/11 at 17:55:20:


Before cutting anything are you absolutely sure your carb is fully functional internally ?  
The drastic drop in rpm when returning to idle and the resulting delay in rpm recovery or engine stop, could be the result of dirty or clogged passageways inside the carb body.
You turned the pilot screw in both directions without effect and that indicates a clogged pilot circuit.  When working normally you will notice changes when adjusting the pilot screw.
This carb can be done in a day on your first teardown.  It is helpful to have the small impact driver that Harbor Freight sell for about $8...used on the tiny screws in the bottom of the slide that hold the needle in place.  Its good to have a bowl gasket on hand too.
There are some very small passageways that control fuel flow and if they are not clean & open the carb cannot work properly and respond to adjustment.
Once you know the carb is working properly then work on the mods if still needed.

I find the brass jets themselves are less likely to clog before the passageways in the carb body itself.  The root cause of a majority of difficulties encountered in trying to tune a carb comes from cloged passageways.
The little brass tube that sticks down from the carb body into the float bowl about 1.5" has a very tiny hole that runs from the tip up into the carb body.  Just below the tip of that tube is also a tiny hole on each side.  Thats part of the pilot circuit and needs to be clear for proper function.
Another item is the needle jet.  With the main jet removed the NJ can be gently tapped out through the top.  It has quite a few tiny holes on the shaft that are usually clogged on an older bike/high miles.
Sudco sells a carb tool that is a small metal case with about a dozen tiny wires of the sizes needed to work on carb bodies.  They work better than any wire you can rustle up and the set is cheap.  The price is worth one clean & rebuild of a carb.  This way you know without question that everything is clear and flowing fuel and/or air.

Just some thoughts.  
Good tuning.