On my 8 HP Honda, the float has nothing to do with idling smoothness, assuming it runs at all. I just turn the carb upside down and eyeball the float so it is level when it is pushing the needle all the way in. I'd clean the carb with carb dip, and if you have a removable low speed jet, try soaking or cleaning it first. When I have rough or no idle cleaning the low speed jet has worked (assuming overall the carb circuits are OK).