This 22mm wide bearing is used in pistons machined to use original piston shims where the crankshaft has big end shims fitted.
The Unofficial Lambretta Manual Update by Mark Haines
LAMBRETTA - ILLUSTRATED GUIDE TO THE IDENTIFICATION by Vittorio Tessera
Lambretta Performance Tuning and Conversions - 8099990
Lambretta Tuning Manual by Dave Webster - 8099992