See, you had HT coils originally made of Bakelite ..which is non-conductive ...so the old bakelite coils had both a GROUND and a HOT (red ) lead coming off of them.
Then you had the PX125 style black HT coils ... which had that big metal mount that bolted to your engine case, and only 1 ( hot - red ) lead coming off the top. The black was unnecessary because the HT coil itself grounded to the engine case.
Now, the Ducati CDI you've got is encased in black or blue plastic. The White wire ( i believe ) is a ground wire from the stator ... but in order to ground the whole CDI assembly, you use that little yellow wire with the ring tab.
They still work if you don't...but i think it's a beneficial thing to use ( until the yellow wire inevitably falls off ).
Modern Vespa is the premier site for modern Vespa and Piaggio scooters. Vespa GTS300, GTS250, GTV, GT200, LX150, LXS, ET4, ET2, MP3, Fuoco, Elettrica and more.
Modern Vespa is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com
All Content Copyright 2005-2025 by Modern Vespa. All Rights Reserved.