Make sure the gaskets are put on in the right sequence and direction. It's very easy to get them on wrong, I know from experience. Also make sure the throttle cable is adjusted correctly so that the choke is closing completely, not just most of the way.
Simple trick to getting the carb, and all the related bits and pieces, back together again without feeling like you need a third hand, is to get two 6mm threaded studs that are about 4" long from the hard ware store. When removing the carb, take one of the bolts out and replace it with one of the studs, take the other one out and replace that one with the other stud. Then slip everything off of the studs, and use them to line everything back up when re-installing. Honda mentions this in their shop manual for the GCV160, but have special studs as they call them with a Honda part number.