Pump circuit tuning
Lots of folks don't understand that the pump jets also serve as a high speed bleed that influences (richens) the far top end of the main circuit. The weight (size thereof) sitting on top of the ball, in combination with the size of the choke, controls when the bleed starts.
As far as the pump stroke--unless you are NOT getting enough squirt volume with the pump return jet down to zero, you do NOT need a longer pump rod.
Once the size of the pump jets (and the weights) are correct for the MAIN circuit, leave them ALONE.
The way to increase the RATE of pump squirt through a given pump jet is to go to a stiffer (or softer) pump SPRING--there are at least five different ones available, Alfa generally used the softest one in its stock settings.
The way to shorten (or lengthen) the length of time the squirt continues is by adjusting the size of the pump return jet (larger=shorter squirt, smaller=longer squirt).
If you have a squirt that gives you good, but not too rich, immediate response, but the squirt doesn't last long enough (you get a lean hesitation AFTER good initial response, then the return jet is too large. On the other hand, if you get a rich spot (puff of carbon) after a good initial response, the return jet is too small.
FINALLY--if taking the return jet down to zero doesn't cure a (delayed) lean hesitation, it's time to go to a longer pump stroke, and work back down from perhaps a .70 pump return jet until things are right.
Absolute waste of time to play with the length of the pump rod otherwise.
Greg