11T front sprocket (NON cush drive type) for Lambretta J50  + Lui 50 (+ tuning). 

Although this is a standard Lambretta part, it has also been added to 'Casa Performance' listings on the website as this can be used for an engine upgrade.

This is the complete list of all possible front drive sprocket & clutch crownwheel sprocket combinations for all J-Range and Lui-Vega-Cometa models, complete with the required length chain (with 'live' product links):

45T Clutch Crownwheel Sprocket
45T clutch sprocket + 11T front sprocket = 73 link chain
45T clutch sprocket + 13T front sprocket = 74 link chain
45T clutch sprocket + 14T front sprocket = 74 link chain
45T clutch sprocket + 15T front sprocket = 75 link chain
45T clutch sprocket + 16T front sprocket = 75 link chain

46T Clutch crownwheel sprocket
46T clutch sprocket + 11T front sprocket = 73 link chain
46T clutch sprocket + 13T front sprocket = 74 link chain
46T clutch sprocket + 14T front sprocket = 75 link chain
46T clutch sprocket + 15T front sprocket = 75 link chain
46T clutch sprocket + 16T front sprocket = 76 link chain

47T Clutch crownwheel sprocket
47T clutch sprocket + 11T front sprocket = 74 link chain
47T clutch sprocket + 13T front sprocket = 75 link chain
47T clutch sprocket + 14T front sprocket = NO!
47T clutch sprocket + 15T front sprocket = 75 link chain
47T clutch sprocket + 16T front sprocket = 76 link chain