SI carburettors - classic rotary slide carburettors for Vespa Largeframe with simple tuning and performance suitable for touring.
The SI carburettors are fitted ex works on almost all Vespa Largeframe models (except GS160/SS180). Their comparatively simple design nevertheless offers precise adjustment options via the main, main air correction, secondary and Choke Jet, Throttle Slide and idle mixture screw - similar to larger drum or flat slide carburetors. They are particularly attractive for non-professionals, as adjusting the Main Jet often produces the desired effect.
- Original Carburettor on most Vespa largeframes, easy to tune.
- Short intake stroke, direct response, ideal for durable Disc Valve setups.
- SI 24.24 (incl. T5 variant) as a discreet tuning for 125/150 and 166-177 Cylinders.
- Wide availability: DELL'ORTO, SPACO and VEMSA as alternatives for bottlenecks.
The short intake path ensures a direct response and makes the SI carburettors the first choice for durable rotary valve engines. With the right peripherals, over 20 hp is possible at the rear wheel, but the internal cooling capacity is limited - Cylinders with high thermal loads should therefore be operated with larger carburettors. In addition to the SI 20.20 for smaller PX models, the SI 24.24 is available as a replacement for the PX200 or as an inconspicuous but effective upgrade for 125/150cc models with tuning cylinders. The SI 24.24 G of the T5 with an even shorter intake path is perfectly matched to the 12 hp T5 Engine and is a popular tuning for 166-177cc models. All SI Carburettors are available in versions with and without separate lubrication.
The oldie faction is also catered for: SPACO SI 20.15 and 20.17 are functional replicas of the early original carburetors. They are equipped with a Choke and therefore require the Air Filter of the PX. To compensate for supply bottlenecks at DELL'ORTO, SI Carburettors are also available directly from SPACO (India) and VEMSA (Taiwan). SPACO variants are very similar to the DELL'ORTO/SPACO versions, while VEMSA are more suitable for simple repair solutions.
Conclusion: Classic rotary slide carburetor - ideal for solidly built touring setups, from the original engine to moderately tuned long-distance scooters.
SIP TIP:
- Always order the matching Air Filter.
- Gasket Carburettor, Jetting Kit Carburettor and an SI jet set (e.g. item no. 40260000) are highly recommended to ensure clean and reliable tuning.
To dispel any rumors:
“Several years ago, DELL’ORTO entered into an agreement with SPACO and PIAGGIO to produce SI-type carburettors in India. SPACO manufactures these carburettors under license and supplies them to DELL’ORTO. DELL’ORTO guarantees the quality and supplies the SI carburettors both to PIAGGIO for original equipment and to other customers for the aftermarket. The carburettors are marked ‘SPACO lic. DELL’ORTO.’”
–Stefano Prandini, DELL’ORTO S.p.A., Italy, May 2008
