The MRP Venturi intake funnel replaces the standard air filter on Dell'Orto SI24/24E and SI26/26E. Depending on the setup, the engine can react noticeably more spontaneously thanks to the freer airflow. At the same time, the way the air correction works changes - which is precisely why the 1/8 to 1/2 throttle range can often be tuned more cleanly with Venturi solutions if the jetting is adjusted accordingly.
With a venturi instead of an air filter, the mixture can react differently to increasing engine speed than with the standard filter. To ensure that the engine runs cleanly, the jetting should not simply be adopted "blindly".
A venturi is not a "plug and play performance jet", but a component that changes the flow and thus the tuning. If the air side (air correction and secondary jet) is not adjusted appropriately, you will quickly end up with a very large main jet - which often makes the mid-range unnecessarily rich.
Recommendation: Tune step by step, document changes and do not run the engine under full load until the jetting has been adjusted correctly.
Suitable for Vespa Largeframe engines that are operated with an SI24 or SI26 carburettor. As SI setups vary depending on the model, air filter solution and carburettor sump, please compare the installation space and carburettor upper part on the vehicle.
The MRP Venturi (MRP580) is a useful component if you want to allow an SI24 or SI26 to flow more freely. Depending on the setup, noticeably more direct response and a cleaner part-load tuning are possible - provided you adjust the jetting in a controlled manner.
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