Motorcycle Repair: Bike shut down while riding, ol lady, tweeks

Question
I have a "77"FX. with a  Belt drive primary/ chain drive rear. I installed a S&S Super E carb on 6-12-04.  It fired up fine other than a few "tweeks" of the idle mixture screw, all was good. I have noticed the fuel filter has not been filling up as far since the change. Driving to work last night,(6-18) stopped for gas, left the store and worked my way thru the gears. While in 4th gear everything is fine then it just falls flat. I coast to the side and hit the starter, it engages but don't fire.  Gas is on, battery is good. All I can get is the starter to spin.  Hauled it back home.  Plugs are Autolites 4265 gapped @.040 they are a week old, they look good. It's my daily ride except for the pick-up the Ol'Lady drives. With it being down, getting back and forth to work is a bitch! from 4pm to 4am. So any advise would be helpfull and appreciated.    Thanks,   Wayne.

Answer
Couple of questions. Looking down the throat of the carb, when twisting the throttle are you getting gas? Removing one of the plugs and holding it against the cylinder, turn the motor over. Are you getting spark? While the plug is out, what color is it?
Mike