Wow you really edited that post, (the auto post notification thingy contained the un-edited post) from what you wrote and deleted it sounds like there could be a bit of dirt or sand or what ever, clogging the main jet, could be varnish too. Did you try simply cleaning it with carb cleaner? Also the attachment says to set the float to 16mm, horizontal will get you close in a pinch but take the time to measure it to be sure.
Do you have a fuel filter after your tank,? Does gas flow freely out the supply line to the carb when it is not attached.