Tuning a Vespa 160 GS 1964 to 180cc

Hello the fantastic people in SIP shop!

I would like to improve my Vespa GS 160 1964, from 160cc to 180cc, but can't find a cylinder to fit.
Your piston, art.No 75004000 is by you said to be used in a GS 160.
I refer to your own text shown down

Piston GRAND-SPORT RACE 180cc,
Big Bore for Vespa 160 GS,
Ø 62,0mm, 2 piston ring(s),
standard 1.0mm, pin Ø=15mm


'Innovazione nella tecnica classica' and unbeatable in price and design! The Vespa GS 160 and SS 180 truly deserve the “Sport” in their model names – and also deserve modern upgrades. Classic model tuning by GRAND SPORT : Technically speaking, state of the art and externally unobtrusive is the name of the game here with an increasing number of components being made available for classic scooter projects. The next logical step after the development of an updated piston kit for the GS 150 had to be versions compatible with both the GS 160 and SS 180 models..............

.......The Vespa GS 160 Race Piston finally enables use of the larger 180cc cylinders on these models. Instead of just the original 58mm bore, 63.5mm and up to 190cc are now possible! This piston is available in the following diameters: 62.0, 62.5, 63.0 and 63.5mm.

But where are the cylinders?


Could you please advice what to do

Hello Malfamartin,


I checked it with our technique department and they told me you could drill your cylinder up to 180cc.

There you could use following piston:



Kind regards

Mario SIP