We got in a new shipment of Malossi big bore kits for Vespa and Piaggio 50, 125 and 150cc engines.
Malossi Big Bore kit for the ET4, LX, LXV and S150, as well as anything with a 125 or 150cc Piaggio leader engine AND a carburetor is $259.93
https://scooterpartsco.com/malossi/malossi-master-part-list/malossi-190cc-racing-cylinder-vespa-et4-lx150-s150
Malossi Big Bore kit for Vespa, Piaggio, Aprilia 50cc 4 Stroke scooters is less than $200. Give your LX, S, Primavera or Sprint some love and help it get out of it's own way.
https://scooterpartsco.com/malossi/malossi-master-part-list/malossi-80cc-vespa-big-bore-cylinder-kit
There's no replacement for displacement.