The enricher circuit is a small passage that adds extra fuel to make the fuel mixture richer for starting and running the engine before it warms up. A 12 volt current runs through the bystarter warming and melting a ball of wax that allows a spring to extend the plunger/needle closing the enricher circuit hole. Generally when the motor is warm the carb is warm too and the wax stays melted, so the bystarter plunger stays closed (extended) unless the engine cools down enough to solidify the wax again. If you follow the wires under the floorboard their should be a connector/plug somewhere. Closing the little enricher passage where the needle goes will effectively close the circuit disabling the bystarter. A dab of JB Weld or a drop of solder will work. You can take apart the bystarter and remove the needle and fasten the assembly back on the carb to keep dirt and contaminants sealed out. It is possible that the fuel mixture is too rich when the engine is warmed up because the enricher circuit stays open. But in my experiences the enricher circuit can add enough fuel to affect the overall carb tuning also, though most noticeable in the lower throttle settings.