Vespa ET4 main jet question

I've upgraded Vespa XL50 4T to 79cc cilinder. Should i change main jet to? If so, which would fit the best?

Carburettor is Kehin CVK 18.



more cc needs more food;-)


use this sets :






Thanks for responce :) but those dosent look like my ones. My main jet is 5x7mm... very small :) It's numer 78. Witch numbers should i try ?

Thank you :)