The clue is in the fact that the engine stalls when taken off choke.....
Fuel starvation, somewhere along the line. If you are happy to continue -
Start by removing the air filter and cover (3 screws and a pipe at the back), slide the carb off its studs and carefully disconnect the choke and throttle rods.
Clean the outside of the carb with cleaner, and remove the float bowl - check for water and debris in there.
Remove the pin holding the float, which will pull the needle valve with it.
The main jet is next to come out, and then the emulsion tube above it.....tapping the carb on a hard surface will dislodge the tube and it will drop out.
Clean everything with carb cleaner, and compressed air if you have the chance.
If you want to clean the slow running (or pilot jet) its under a phillips screw below the throttle stop screw which has to come out. the slow running jet isn't removable.
Clean the carb again, and blow all of the drillings clear, including the small hole visible at the venturi which supplies the pilot jet with air.
Reassemble!
The biggest issue with these is replacing the carb with all of the gaskets and spacers - You need four hands! Some times the gaskets survive, sometimes they don't.
Be lucky!
John