The SI carburettors are fitted as standard to all Vespa Largeframe models (apart from the GS160/SS180). Their design is simple in terms of its structure and thanks to the main jet, main air correction jet, idle jet and choke jet, throttle slide and idle running mix regulating screw, they offer similarly precise setting options as the larger drum or flat side carburettors. They are also easy for non-professionals to tune as adjusting the main jet normally achieves the required effect.
Their shorter intake duct helps the throttle response of the engine and makes the SI carburettors the first choice for rotary valve engines. With an SI and the corresponding peripherals, over 20 PS are possible at the rear wheel, their cooling capacity is rather limited, however. For this reason, it is better for cylinders under strong thermal load to be driven with a bigger carburettor.
In addition to the SI 20.20 for the smaller PXs, we also offer the SI 24.24 carburettors from DELL'ORTO. These are not only used as a spare part for the PX200 they are also a decent and effective upgrade for 125/150cc models with tuning cylinders. The SI 24.24 G on the T5 has an even shorter intake duct and is configured perfectly for the 12 PS 125cc T5. Therefore this carburettor is also a popular tuning set for the 166-177cc. All of these SI carburettors are available for models both with and without separate oil injection. With the SPACO SI 20.15 and 20.17 carburettors, we are able to offer owners of classic models fully functioning replicas of the original carburettors. As they are fitted with chokes they require the PX air filters.
Conclusion: Classic rotary valve carburettors. Optimally designed for solidly built touring setups.
SIP-TIP: Always order the matching air filter at the same time. The carburettor seal, carburettor gasket and SI jetting kit (e.g. #40260000) are all recommended.
SIP community user ‚thePhantom‘ (on part no 28532800): „Qualité – prix très bien!!“