The Italian firm Innocenti developed and produced gearboxes with various ratio set ups to suit each individual model of Lambretta. This provides Lambretta tuners with a wide variety of gear cogs/ratios to perfectly suit the character of their motor and the state of tune. Regrettably these original items are long out of production, making serviceable original gear parts as rare as raw steak.
The SIL version even has a slight improvement over the original included as the ratio gap between 3rd & 4th has been reduced, improving top end acceleration. This advantage however, has been achieved at the cost of raising the 3rd gear ratio which in turn increases the gap between 2nd & 3rd. PINASCO have a input shaft available for this gearbox that shortens the 3rd & 4th ratios and retains the short gap between two while also bringing 2nd & 3rd closer together. This combination creates an easily ride-able gearbox set up, especially for tuned motors with narrower power-bands.
The gear ratios found in the original gearbox are : 10/50, 12/42, 16/38, 18/36.
When the PINASCOinput shaft is added they become : 10/50, 12/42, 15/38, 17/36.
Conclusion: A meaningful upgrade for the Indian produced GP200 gearbox : 10, 12, 15, 17.