The Gori RV4S 4-Speed code ratio gearbox has now been added to the visualiser.
The Gori website details the thinking behind the ratios on this gearbox as well as some detail on the production process.
This sport gearbox was designed and developed by Gori Elaborazioni and entirely manufactured in Italy by Micozzi Ingranaggi [Macerata]. RV4S is the state of the art solution to enjoy maximum engine torque no matter what is the tuning configuration of your Lambretta. RV4S is made of a robust alloy of of nickel-chromium-molybdenum 18 nc 05 and it is specially treated with a process of carburizing and quenching. Gearwheels are at least as thick as the original ones. RV4S is a very precise and robust product at an affordable price.
RV4S was specifically designed to achieve the best possible performance ratio at any times and in any gear, thanks to the fact that torque is more prompt and available at higher revs.
First gear is rather elastic while the other gears are very tight to each other, which allows to ride uphill hairpins in first gear and then enjoy the very tight second gear for quicker output. When shifting, the decline of revolutions is very limited, thus allowing the best possible progression with no significant loss of power. As a matter of fact, our road tests confirmed that the best performance is obtained on uphill riding and on combined cycles.
RV4S can be fitted both on tuned and on standard Lambretta engines. Transmission is easily mountable and fits the standard selector (which doesn’t even need to be replaced).
For lovers of technical values we will be glad to provide the graphs of some of our tests with different pinions with different number of teeth. Our applications show that the decline in the number of revs when shifting is very limited: percentages range between 22% and 18%.
More detail and photos on the Gori website
UK distribution appears to be through Cambridge Lambretta with a retail price of £425