[Technick]

The hesitation could be from a power valve mismatch to the engine, this is the point that the fuel inrichment ocures. Try to get a power valve rated at 2-3" hg less than the vacume reading of the engine at idle. Also the "cam" that dictates the rate that the accelerator pump squirts could need adjustment. If you look closely at the actual linkage that causes the acelerator pump to move you will see a colored plasic cam that causes the lever to move which in turn thru another lever causes the accelerator pump to move. That plastic cam is adjustable by one position or you can replace it with a cam that has a faster ramp, or less agressive ramp as the case may be.