if the above suggestions don't do the trick, it sounds to me like the idle circuit of the carb is closed and not working. when you close the choke , you are drawing fuel from another circuit to keep it running. either the mixture screw is turned in too far, or the idle circuit is clogged. check to see that the mixture screw is at least 1 1/2 turns out from being bottomed out for an initial adjustment. if it won't run with this adjustment, the carb might need to be thoroughly cleaned. i have not had good luck spraying wd40 around carbs. it tends to leave a film that is great for rust prevention, but it will stick small metal parts that are meant to move freely. good luck
