Problem with my Piaggio Zip after fitting a Polini Sport 70cc

Hi
I am new here and I am new to scooter tuning and hope I could get some help with my setup.
English is not my native language so I apologies for my spelling error.

I just got myself a Piaggio Zip 50 2T AC 2012 and after a week I wanted some more power.
I ended up with the Polini sport 70cc and a Touring exhaust system.
After installing I have also removed the plastic plug in the air box and also the metal plate on the carb inlet. (Hope you know what I mean)
I have fitted 6g rollers and removed the metal ring on the variator.
My stock main jet is 53 and I was told I should start with a 75 after tuning and see how that worked. I have also tested 3 needle positions which are low, lower, lowest (where low is middle position) but cant say I notice any different.

So my problem is that when I start to run, the engine is so jerky at the beginning but if I give some more throttle (like wot) all is fine.
I will try to record a video so you can listen.

Thanks

 

Here is a video I made

picture of my carb

 

Looks like the problem is from like 1/8-1/4 throttle. This is where the pilot jet is working or?
But I cant find anyone that had to change it on a tune like this