use the "final adjustments" given for the WD4s in the general instructions booklet to adjust your carb.
The WF-4 parts diagram is further down to take apart the carb.
You may want to use carburetor cleaner and blow or rod out the passages for the idle. You may even need denatured alcohol to clear up shellac deposits. Waterlogged cork floats can be dried and coated with super glue to make them impervious to gasoline.