Ignition off.
Remove air cleaner.
Disconnect auto choke wire from carb top
While holding the choke plate open, look inside the carb throat with a mirror and a light. Pull throttle lever down, you should see th eaccelerator jet spray a thin stream of fuel down the throat, accompanied by a hissing sound. If not, the carb fuel bowl is empty or the accel pump is not working.
Remove all 5 screws that hold the carb top in place, pull them out and put them in a jar before removing carb top.
Carefully lift carb top off. May need to tap the sides a little. There's a paper gasket in between that may be stuck to either surface, or both. Try to help it come off with the carb top as you lift it up slowly. Help with a razor blade or something. Don't drop anything down the carb throat.
Once the top and the parts hanging off of it have cleared the carb, you can move them sideways and even turn the top upside down. Take note of how much fuel is in the carb bowl. With the float floating around on the inside, there shouldbe fuel almost 1/4" from the top edge. (Close enough to make it run, that's not an accurate measure)
Now when you look at the underside of the carb top, the needle valve should be clearly visible, I think it takes a 1/2" wrench or smaller. It has a fiber washer under the hex head, don't lose or break it. Sometimes it's aluminum. Take the valve out and clean it with compressed air and WD40 or whatever you can think of. The needle thingy in the middle should move very easily.
Pull the float out too. There's a plastic, curvy little thing sitting on top of the float hinge pin. Pull the plastic out first, then the float. Don't tilt the float, the hinge pin is not secured to it and it will slide out very easily.
Shake the float and listen for sloshing. Sometimes they may be punctured and partially filled with gasoline. (=broken beyond repair, most would say). It's pretty rare. It would cause flooding, TOO much gas going into the engine.
Now look at the bottom of the fuel bowl where the float used to be. Remove all dirt and crud. you can drain the bowl by removing the hex head plug at the bottom, on the left side. Fuel will then spill down on the engine so I suggest you try to catch it with a rag or something. Poke around with a wooden stick or heck even a screwdriver, to knock off caked on dirt from the bottom. Chase it all out through the drain hole.
This is how you get access to the main jet too. It's sitting sideways, hidden at the bottom of the bowl, at the end of the little U-channel that starts from the drain hole. By inserting a flat head screwdriver through the drain hole, you can unscrew the main jet and take it out for cleaning.
The idle jet is on the outside of the carb. There could be 1 or 2 of them, depending on carb model. if there's 2, pull out ONE at a time, then put it back before pulling the other. There's a slight size difference, they are otherwise identical. Don't ask me which one is which. You can blow the jets clean with compressed air, and also the passages behind them. Do not push an air gun nozzle up against the jet hole in the carb, it's bad practice and may damage some carbs. instead, while there's still fuel in the carb, blow air PAST the idle jet hole opening at an approximately 90 degree angle. The airflow at the mouth of the opening will create a vacuum inside, and pull whatever is in there, out. Including a mist of fuel sprayed all over the engine bay. (Good time to quit smoking).
installation is the reverse of teardown, more or less ;)
this should sort out your carb basics.
There's a procedure for properly adjusting the carb too, but we can get to that later.
You can test the fuel pump too by the way. Pull the hose off the carb top, and route it into a container, an empty coke bottle for example. Secure the hose to the bottle and the bottle to someplace safe. The hose will try to flop around a little when th epump starts pumping. NOW pull the ignition coil small wire off, the one that does NOT come from the distributor. Now you can spin the engine with the starter without actually starting it. have someone crank it over while you look at the fuel outlet hose. Fuel sould shoot out with force in pulses when the engine turns over. It may be a good idea to let the pump run for a while, to flush out any dirt that may be trapped inside. I mean just for a few seconds.
jan