hairy apple wrote--"Another problem is that there is a brief hesitation when the accelerator is stomped."
I do have a fair amount of experience with the Weber. I doubt if the fault lies with the secondary jet. They are not so fussy about the secondary jetting. If too lean the performance wont be there---too rich and you might be trailing a cloud of black smoke.
The transition between large changes in throttle opening are smoothed with the direct injection of a fuel stream via the accelerator pump nozzle. The pump diaphragm is easily changed with the carb on the motor. You should see a steady stream of fuel out of the nozzle (primary side only) as you open the throttle from closed to wide open. The diaphragm is available as a separate item. Years gone by in my Fiat/Alfa owning days I used International Auto Parts by mail order. Many Fiats and Lancias used similar Webers--and the parts are mostly interchangeable. BTW--great point by Ron Kwas regarding the shape of his feeler gages. Mine are mostly worn and need replacing anyway. -- Dave