Modern Vespa

After having starting issues on my 02 vespa Et4 I purchased a brand new cvk26 and swapped out the old walbro carb , it now starts like a dream but on low throttle or initial pickup theres as slight hesitation when you give it full throttle
Mid range and top end seems to be fine.

The other thing is that I think the idle is too high so my question is would a incorrectly set idle mixture screw cause the hesitation?

Many thanks

First, get the idle mixture right. With the engine fully warmed up, turn the idle throttle stop down until you have a low steady idle, then adjust the mixture until you get the highest revs at idle. Rinse and repeat until you get the lowest steady idle.

Then check the accelerator pump is working OK - it should be on a new carb, but perhaps some mechanical adjustment is needed..