A new aluminium cylinder kit aims to give Vespa Largeframe owners usable road performance without sacrificing everyday manners.
SIP has added a 177cc performance cylinder to its Vespa Largeframe range, developed around broad power delivery, touring reliability and scope for further tuning. Although the company classes it as a racing cylinder, the stated brief is very much that of an all-round road kit rather than a peaky, single-purpose motor.
The coated aluminium barrel uses six transfer ports and a single exhaust port, feeding into a bolt-on steel exhaust manifold. A coated 63mm piston carries two 1mm rings, while the supplied cylinder head is secured by eight bolts and sealed with an O-ring. The cylinder runs with the standard 57mm stroke to produce its quoted 177cc capacity.
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Compatibility has been considered carefully. Every installation uses a 4mm base spacer, and the kit includes separate spacers and paper gaskets for both two-port and three-port engine casings. Those gaskets allow the fitted height to be adjusted during assembly. SIP also describes the cylinder as generally compatible with Electic-start engines, although minor grinding may be necessary around the starter ring gear because of production tolerances.
SIP’s published starting point is a 19-degree ignition setting, a 110-118 main jet and a 1.4mm squish clearance, with an NGK B9ES or Bosch W3CC spark plug. Those figures should still be treated as setup guidance rather than a substitute for checking the individual engine, carburettor, exhaust and fuel combination.
The complete kit is listed at €289. For riders building a practical 177 that can handle everyday use and longer journeys, it looks like a sensibly specified alternative in an already busy part of the Vespa tuning market.
More info: https://sip.shop/177
