Modern Vespa

Hi Vespa experts, hoping you can help me out.

I am trying to eliminate the battery on my GS. I bought a new VBB stator and transferred all the coils and condenser onto the GS stator plate.
I thought connecting black and red wires from the stator to the AC coil would produce a spark but no.

Timing is correct and points open and close correctly. Magnet strength of the flywheel good.

Should I connect red to coil and black to the body of the bike earth?

Is this method going to work? What AC volts should I see from the various wires?

Thanks all!

Look at a VBB wiring diagram to understand how it works. It's pretty simple.

You can modify a VBB harness or make your own.

You will have to change the brake switch to a non battery circuit breaking "on" switch. Plus, modify the key switch and the light switch if you want to keep the originals. You are going to have to get creative here. I wired the key switch to ground the ignition coil when the key was turned to off. I had to jumper a wire to do it.

https://www.scooterhelp.com/electrics/pages/VBB.150.html

Notice this is almost the same.

https://www.scooterhelp.com/electrics/wiring/VSB1.nobatt.pdf

Thanks for your reply. Appreciated but my issue is just with the spark.

I am trying to use an AC CDI but it won't spark. I just wanted to check the wiring is correct. Stator black wire to earth on the body of the Vespa, red to coil. Not looking for lights or horn or kill switch at the moment.

That won't spark but I am not sure why. Will have another look in the morning but I am a bit lost.

I don't know anything about a AC CDI.

All I can add is that if you have the Stock VBB system wired correctly and it doesn't spark, I would test the internal and external coils to verify they have proper continuity and resistance.

If I have a problem it's usually a bad (new) part. Coils, condenser, spark plug.

They don't make things like they used to.

One more thing, make sure the ground (Black) wire is also grounding directly to the engine/stator plate. The body ground relies on a separate grounding wire and sometimes those are bad/weak.

Looking at your picture the spark plug body is not grounded.

OFG

I assume you had the plug grounded to the body of the coil?

The stator looks right to me but maybe the break in the yellow feed to the points is arcing? The yellow to the condenser should also be connected at the points. I can't tell where the yellow from the blue/yellow coil is routed. It also looks like you have a resistor cap which is not needed for the points ignition.

Yellow ignition feed. Off of stator: Yellow to handlebar switch, Red to HT coil. Black-ground, Blue-brake light, Green-horn.

Morning helpful people,

Having another look at this. Issues and no spark but then took apart the coils on the stator and put it back together and suddenly spark. Engine now running. Yay!

Typical Vespa.

Got front lights working but I think I need to do the following:

Change horn to AC horn
Figure out why rear light isnt on.
Change brake switch to interrupt (or the opposite of whatever is in there now).

Plan is to have switch all the way to right, everything working. One notch to the left kills the engine. That part is working.

Thanks!

Which switch ?

The ignition switch.

Final challenge. Everything connected and working but when I connect the brake switch red and blue wires the engine dies.

Will touching the red wire to ground kill the motor? Red is typically the ignition circuit.

On the ones I have worked on, the brake switch wires should be blue and black. Is there a two-wire branch off the main harness for the brake switch?

Got a blue and red brake switch connection. This is a GS battery model. Electrical issues hurt my brain.

GS wiring diagram shows wire from switch to horn to brake switch (red) and brake switch to stop light (blue). Connected until brake is pressed.

Clearly, I have no experience with battery models... good luck.

Apart from being Indian crap, this stator is for a non battery model. The red wire is only for the ignition...

What's wrong with your original stator??

What harness are you using? The original battery harness?

The original harness won't work unless you modify it.

That is why I said you need a VBB harness to keep things simple.

The tail light on a VBB style coil is on a separate circuit and is grounded until you step on the brake pedal and the switch cuts the ground.


I'm guessing that is why you are not getting a spark with the original brake wires connected. You are grounding the ignition through the brake switch. That won't work.

Battery circuit diagram shows this.

https://www.scooterhelp.com/electrics/wiring/VSB1.1.pdf

Thanks all for your input.

Using VBB coils on GS Stator. Now have spark. Engine runs. All good. All lights are working. Brake light comes on. Don't think I need to change the harness to a VBB harness. Only need to figure out brake light switch so that it doesn't cut the engine. Think I need to disconnect the brake switch from the ignition.

The reason for the switch is to eliminate the battery.

The VBB stator has four circuits plus ground going to the junction box. It looks like the GS160 battery version feeds power to the ignition switch on a single yellow wire where a red wire gooes to the brake switch that closes when the pedal is pressed so power goes through the blue wire to the bulb.

I am curious how you connected the battery harness to the five wires from the VBB stator. Maybe I am seeing it wrong, but is there not only one yellow wire and one black coming from the junction box?

I have connected one of the outputs of the stator to the yellow wire and that powers all the lights.

Another output of the stator is connect to a black wire in the junction box. This runs out of the body at the spare wheel where the regulator used to be. I connected this to purple wire which lights the brake light when the pedal is pressed.

At the moment nothing has been cut or removed or altered. Many things are not connected.

Ignition switch is position 3, on. Position 2, engine dies.

How about a PHOTO of this "ignition switch " & whats going here... e ae known fo having crap imagination, especially when electrics are involved

Will do. Let me figure out the brake switch then will take all the pics.

From what I can tell.... the original system powered the ignition switch from multiple coils on the yellow wire. If you have tapped just one coil on the VBB stator ( yellow?) there may just not be enough juice to power the ignition and the lights and the brake light. I don't understand connecting the purple wire to black as it looks like it would just ground the whole thing...

It's real simple.

If you are switching to non battery VBB coils you also need to wire it like a non battery VBB. How you do it is up to you but...

The non battery VBB system has three lighting circuits and the ignition circuit. They must be wired separately in order to function correctly.

The headlight and the horn are on one circuit, the pilot lights and the speedo light on another and the brake light on another. All separate so they function AND balance power to the bulbs.

You can't wire it randomly. You have to wire it like a VBB non battery system.

I know its a pain in the ass to install but I'd skip the confusion and get a new VBB non battery harness. Do the conversion right the first time and skip future problems with a converted OLD harness.

Agreed. The trick would be incorporating the ignition switch. I'd just just leave it out entirely and use the VBB switch unit.

You can move the kill button wire to inside the headlight housing and connect it to the key switch. I did that by jumpering a grounded wire to the "off" position pole on the switch so it kills the engine with the key.

I'm not sure the stock battery GS160 has a VBB style switch mount on the headset. The non battery GS160s did have that style switch mount.

I know the late model GS150s did not.

Hi, thanks for your suggestions. Have spent the entire day dealing with the Vespa. Was running fine all morning then suddenly started misfiring and wouldn't run.

Now back to square one with NO SPARK AGAIN!!!

This bloody bike is a pain. Stator had a broken wire which I have soldered. Still got no spark. Tried two different CDIs

Any suggestions based on looking at this stator that was working fine this morning.

Thanks all.

The stator looks OK but, because the original was completely different, the issue is how the VBB coils are connected to the original harness.

I'd like to see how you connected wires at the junction box. What are the yellow, blue, green and red wires connected to? Black is ground. Which coil is powering the ignition and which the brake, horn and lights? Are you only using the yellow wire? You said you connected the purple wire to black, which would just ground it.

As endoftheroad said, "You can't wire it randomly. You have to wire it like a VBB non battery system. "

Could you not have been able to just eliminate the battery and add a regulator and maybe move some wires around at the switch and run the whole system off the original stator ?

I can't do anything or solve any wiring issues until I can start the bike so will get to that once I solve this.

Have a couple of other options to try.


Thanks

There is not much more to be said. The VBB non battery system is about as reliable and simple as it gets with an old Vespa.

I have used them for decades without any major issues.

If you wire them up right and have good working parts they work.


Maybe find someone who is well versed in vintage Vespas for help?

Just a quick one on VBB stator output. This gives three outputs of varying AC voltage. Green highest so use it to power the lights on the GS. Yellow second highest so use it for brake light on the GS. Blue lowest output voltage so use it for the horn. Black unnecessary as it is earth. Red for CDI.

I get the need to not be random but ultimately the wires in place on the GS will carry the required voltages to the required components without the need for changing harnesses.

This would be relatively straightforward if I could start the bloody bike. Grrrr.

This forum! Definitely helpful. Thanks!

Why go to all this trouible to lose the battery?

How should I do it?

Just wondering why you want to eliminate the battery.

Ah I see. I couldn't get it to charge. Should be simpler without it. Also have a second battered GS with the same issue.

Did you try replacing the rectifier? (Looks like there's a fuse in it as well.) As I said, I have no experience with battery systems on these bikes but that was the issue when my John Deere mower stopped charging.

Yep, with a lovely modern all singing all dancing rectifier. Couldn't get the charging voltage up enough to charge the battery. Old rectifier, new rectifier, battery would die after a couple of days.