Not enough fuel.. Either an air leak between the carb and intake or intake and block..
Passage ways in the carb are gummed up, the carb is the wrong size or worn out..
As long as the carb isn't total junk it should run for the most part though.. The screw sunk into a brass bolt at the vary far bottom of your carburetor is your main fuel mixture.. The small flathead screw penetrating the body of the carb from the left side near the intake manifold is your idle fuel mixture...
GENTLY!! screw them both in till they stop moving (BARELY STOP MOVING) If you can get your fingernail into the slot on the screw, you should be able to screw it in and out without breaking a nail... Overtightenting will ruin screws and jets and stuff..
But.. screw both of those fuel screws in until ya feel them bottom out.. Screw the idle out about 1 1/4 complete turns, and the main on the bottom like 1 full turn out... If the carb is functioning, you SHOULD be able to rev the engine up enough for it to run all by itself with no choke....
About the best you can do is get those screws about half assed right, then hold the throttle full on wide open or as close as needs be, for the engine to continue running with no choke on... Then kinda work on dialing in your main screw slowly until the engine runs good and strong and revs up good with good throttle response.... THEN if ya find that point, the main fuel is pretty close.. Then you can work on setting your idle speed, so that you can leave your hands completely off the motor and it will idle by itself... Then you can move on to adjusting the idle fuel.. Slowly adjust the idle fuel screw in or out until you can hear the engine pick up speed and smooth out and start idleing high.. Then you can go back to adjust the idle speed again.....
It's kind of a trick balancing all of the screws out so everything is working perfectly together.. Sort of a trial and error type thing.. you'll be screwing with screws for a while until ya find a magical medium.. :laugh:
I also ALWAYS test run and dial carbs in with the choke not on... I will shoot it with starting fluid, or hand choke it so it gets a good shot of fuel, and I KNOW it will at least start and run for a second... If it runs for a second, you can start throttling by hand and screwing with screws... It should run with no choke.. So thats how I do them.. Only actually (use) the choke, when starting the engine cold, and it already is known to run good..
