Starts fine idles fine , when I let off trottle it quickly shuts down, had these symptoms before but they seemed to go away when I emptied gas tank and put in new fuel, bike is seldom used sits a lot with no gas additives to prevent the gunking issues, at higher rpms I do get a lot of backfire , plugs changed air filter changed still no resolution of sudden shutdown after acceleration, considering carb clean out next , or any other suggestion that might help

 

Add the proper amount of Seafoam cleaner to a full tank of gas and ride it all out in one shot. Use it regularly if the bike sits for extended periods. I've had good luck with it in dormant bikes and other gas engines.

 

I would definitely clean out the carburetors. Definitely sounds like a fuel issue and try not to run out of gas. You end up getting all that sediment at the bottom of the tank in your carbs. You might try mystery oil or as someone else said the seafoam. Good luck!

 

If you have a lot of backfiring at steady rpms you have a lean condition. You probably want to verify there are no intake leaks. If none are found, ride the bike and pull out the enrichner. If it smooths right out, drop the bowl and look at the slow jet. Also, make sure that your idle rpm is set to spec and not too low. Those are probable the most common easily checked items. If someone has had the top off the carb, you might want to check the diaphragm isn't pinched or torn if you don't find anything else.