Modern Vespa

Malossi has redesigned their Big Bore Kit for the 250cc Vespa engine, and made it even bigger. Now the cylinder diameter is bigger than a stock Vespa 300, and as big as a Vespa 300 with a Malossi cylinder kit.
Get your motor running and head out on the highway. Find out what 95mph feels like on a Vespa.
The old kit has a 74mm diameter piston. This one is 75.5mm. The stock 300 is 75mm.
In Stock at Scooterpartsco.com

https://scooterpartsco.com/malossi/malossi-master-part-list/malossi-271cc-racing-top-end-kit-for-vespa-250-piaggio-250

https://scooterpartsco.com/malossi/malossi-master-part-list/malossi-271cc-cylinder-kit-for-vespa-gts-250

Slightly deceptive advertising here. The diameter may be bigger, but the capacity isn't. The 300 is 276cc. The 300 has a longer stroke - 63mm where the 250 is 60mm.

The old V4 kit brought the 250 up to 268 cc. So now they give us 3 cc more. Big deal! 1% increase! Why the hell did they bother?

Mike

Well said, Mike!

Well said, but not at all accurate. There is nothing deceptive about stating that something is bigger if it is. The bore is bigger than a stock 300. The increase in displacement over the old kit for the 250 is 10ccs, not 3, and 20ccs over stock, and the increase in displacement on the Cylinder kit Mike installed on his 300 over stock is 4ccs So Mike is probably in a better position than most to tell you why you should bother.