Modern Vespa

Hey there!

I have a 74 Super 150 VBC1T and I cannot figure out why the battery won't charge. The lights all work, the scooter runs and drives well, but I'm not getting enough power to the battery to charge. I've tried a number of things, replacement parts, wiring changes, etc, which I'm happy to get into if folks think it's relevant, but I think I've narrowed it down to the stator output. When the scoot is running at idle, I get about 2.6v AC from each yellow wire, with a multimeter grounded to the engine. Also, at idle, I get 4ish volts DC from the regulator, going to the battery (multimeter grounded to the frame).

My assumption is that I should be getting higher output from the stator (like 3+ volts AC each), which would produce ideally over 6v going to the battery. Is that a correct assumption? If that is correct, does this point to a bad stator or a insufficiently magnetized flywheel? Or something else? This is the last gremlin I'm trying to work out of this complete rebuild and it's driving me crazy! Please help!

Thanks in advance!

What's your voltage output at say 3,000 rpms? Measure at the two battery terminals. Are you sure your battery is not shot?