are you sure it doesn't have an "air bleed" screw that you are turning...........never seen or heard of the FT 1.20 coming with any carb other than the air bleed.........even version II and the first 1.60's came with air bleed carbs. did you buy a different carb?
otherwise, if in deed it is an airbleed carb and you have the screw almost closed, then that sure describes what you are saying more so than anything else.