The books aren't much help when it comes to cleaning the carbs on these engines. You really, really , really need to study the carburetor assemblies very carefully after you take it apart and familiarize yourself with each and every internal passage. I'm not sure about yours specifically but most have three tiny holes in the top of the throttle bore, on the intake manifold end, that are drilled in a sort of "triangle" pattern.
One is the idle circuit passageway and can be seen with the throttle plate seated or closed. Make sure that you remove the idle mixture screw and flush and backflush that passage thoroughly with the screw out. The straw that comes with a can of carb spray works great for covering those tiny holes and backflushing with the pressurized fluid.
The other two holes can be seen when the throttle plate is opened and propped open. Those are the "transition" and the high speed circuits. Find where they are being fed from the float bowl and jet assembly and flush through that passage. You will probably see fluid escaping through the housing for the idle mixture screw while doing this so hold your finger over that opening while flushing.
All three of these orifices must "gush", not dribble, fluid when completely cleaned. Pay particular attention to any passages in the bottom of the float bowl. Study where any internal drilling goes from the bowl up to the main body and make sure those are all clear by flushing with spray. I frequently use more than one can to clean up a carb.
Study the jet tube and make sure that it is showing daylight up through the center and that it is not cracked. If it is cracked, you can't get it clean or, you're just not sure, replace it.
Don't reuse the old seals, especially the tiny Orings for the idle screw and the jet set. It is CRITICAL that you achieve a good seal at these points and great care should be used when reinstalling so as not to "roll" or pinch the seal rings.
Good luck.
