Forget the hassle of tightening the old style clutch castle nut and tab washer with a specialty tool.
This fanged clutch nut and wave washer will make that job easy, and requires no Vespa specialty tools.
M12 Clutch Nut and Lock Washer, AF 15mm, DRT, clutch
For Vespa 125 V1-TS/150 VL -Super/160 GS/180 SS/Rally /PX80-200/PE/Lusso/Cosa/T5
Also for Femsatronic Vespatronic flywheel/ Pinasco Flytech ignition for Vespa 180/200 Rally VSE1T -> 33996, Femsatronic, with flanged edge
MINdfriz V.U pig. 196 DRT (DRT), 25070102 (PINASCO)