Modern Vespa

I've got a BV200 that stopped charging the battery. I have an electric fuel pump on it, and an electric water pump. It is a carbureted bike. The speedometer is electronic, and it works when it wants to, but it's been like that for a while. The LED strip does the same thing, but they don't seem to do it in unison all the time. All the lights and switches work.
It has stopped charging the battery, and I can't figure out why. When I connect the battery, there is an electrical sound coming from somewhere in front, almost like an electric fuel pump for efi, for about half a second, that I haven't been able to track down yet. I don't remember if that's normal or not.

I have:

Replaced Voltage Regulator
Replaced CDI 2 times
Replaced Stator
Replaced Flywheel
Disconnected fuel pump.
Replaced Battery
unplugged cooling fan
Disconnected water pump.

And it still won't charge the battery.

So now I'm thoroughly bewildered as to what else could be preventing it from charging the battery. And my understanding of vehicle electrical systems is fairly rudimentary.

Open to suggestions.... If I can't figure out a way to make it work like it should, is it possible to run a wire directly out of the V/R back to the Battery?

Isn't there already one there?

Yea you absolutely can bypass the harness and run wire from the VR to the battery or however the wiring diagram shows it.

Two questions- Have you confirmed AC voltage at the stator and VR in and any DC voltage out at the VR?

Sounds silly but is there an inline fuse on the charging circuit going to the battery?

First of, the sound you hear, is probably coming from the speedo which is "homing" the needle (it's operated by a stepper motor). Now to your problem, you basically replaced every part. Leave the LCD disconnected and see if you have charge. Years ago, we had a customer's Skipper 150 4T (ugliest ever scooter made by Piaggio BTW) with the same problem. It turned out to be the LCD screen. It was acting up like yours, before the problem started...

I disconnected the screen, and it's charging. But I can't get it to charge over 13.9 or so. Even right out of the voltage regulator, it's hitting 13.89 or so. I've disconnected the electric fuel pump and taken it as high as 11,000 on the tach, and it won't hit 14 volts. Any ideas as to why this is?

Have you tried a different voltage regulator now that youre getting 13.9? I've had bad BGM ones before.

Did Piaggio start using a different voltage regulator manufacturer since that scooter came out?

All I've got right now are the Piaggio ones. I think they're Shindengen. They are dated 17-12 on the bags. Right now the head and tail light are off the bike, so the load should be pretty low, but it's not setting any records in the voltage making department.

Wild idea but is the AC IN wires from the stator to voltage regulator isolated or do they branch off to other things? Maybe theres a short in one of those/ some kind of draw? I'm grasping at straws here.

I haven't run them down and really don't understand wiring diagrams. It looks like three out, three in, but I'm not sure. There is some intermittency to the problem that makes me think it involves a short or faulty mechanism somewhere.

Works slow so I looked at a few wiring diagrams for BVs in the Wiki section. All of the ones I looked at show three isolated wires going from the stator to the harness. Then 3 yellow wires in to the voltage regulator, a ground and then one or two red wires out to a fuse and then to the battery. Pretty standard setup.

Have you tried testing resistance values on the stator? Manual says .2 to 1 ohm between all the yellow wires.

I think that's the right track to focus on. You've replaced everything but the wiring. Specifically, I would look for cut wires or connectors with corrosion on them. Anything that would resist the flow of electrons or cause them to fall out onto the ground.

It won't go over ~13.9 - 14.0V until the battery is fairly well charged, as on these Leader engines there's bugger all spare current left (~2 or 3A) for battery charging while running the bike's electrics. Starting at half-charged, a 12Ah battery will want 4 to 5A to spike it to 14.6V in its bulk charging state.

Fully charge the battery from a separate charger first, ensuring it rests at 12.6 to 12.7V. Then try.

I have been chasing this as either a fuel delivery or coil problem for quite a while, because it slowly ran worse and worse, but I had a pretty good battery, so if I let it sit, it would start and run again, and for short distances, it was hard to tell it was the charging system. If I got on it, the engine would start to stutter and fail at high rpms, much like if it wasn't getting enough fuel or the coil was breaking down.
One of the other side effects of this is that there is a lot of carbon build up in the head and exhaust from incomplete combustion.

Have you tried to see if there is a draw on the system after the bike is turned off? With the bike off, take the + battery cable loose and put a meter from the + battery post to the cable. There may be some draw from the CDI but im guessing its very little and Id bet that draw is in the service manual. Maybe its charging when the bike is on and discharging when its off

Hey Moto, any update here? I have a BV200 and while it's not having this problem I'm curious about if/how yours resolved.