55 what carb.

there could be several problmes.

1) float level as you mentioned try setting 1/32 lower then specs if you have an old carb

2) too much fuel pressure coming to the carb from the fuel pump and is is pushing the needle open

3) bad seal somewhere in the carb and could be leaking from there try tightening th air horn by 1/2 a turn

good luck

chaimv