Loosen the large hoses at the carb and turn the carb over.
This is a picture of the bottom of the carb. Remove the four screws at each corner of the float chamber, you will loose about three table spoons of fuel, so put a cloth beneath to catch the spills.
Inside the carb you will see two jets, the large "stack" is the main jet and the recessed one is the idle circuit.
Remove these jets and soak them in carb cleaner and blow through with compressed air. Do not poke through the holes with a metal instrument!