Modern Vespa

Hello, let's see if something similar has happened to you with this ignition model and you can give me a hand.

I have installed according to the scheme for Vespa PX models (my vespa does not have a battery) the VMC variable ignition kit. I still have the original regulator as indicated in the diagram (I have tried the regulator from the VMC kit and I can't get the lights to work).

Problem:
The engine starts without problems, but the lighting is not working well, at low revs only the front and rear lights illuminate (very weak), the indicators do not work. When I accelerate the lights illuminated more intensely, but the turn signals barely light up and blink very slowly (as if there was a lack of power).

Tests performed:
- I have checked all the wiring in case there was any grounding or a cable making bad contact.
- I have checked that the regulator receives accelerating between 26 and 29V AC.
- I have checked that the regulator outputs 12 or 13V.
- I have checked all the bulbs and they are new.
- I have followed the wiring diagram of this model of Vespa and the wiring is all good.

I don't know what else to test, is there anyone with a similar experience with this electronic ignition model?

Thanks
RG

Sounds like a normal PX. Doesn't matter if you have a battery or not, everything runs on AC.

Lights were never that bright at idle. Blinker unit might need swapping out if it's old. Have a spare one you can test with?

Hello 108,

I don't have another blinker unit, but I have tried with a motorcycle battery (12v DC) connected (-) to ground and (+) to the gray/green cables (current regulator output), with the engine off and everything works apparently fine.

I am going to try to lower the watts of the headlight bulb (now I have 35W) and I see the electrical diagram says 25W. But or should this be the problem, with the original ignition everything worked fine without changing the bulb from 35W to 25W.

Electrical problems are always very entertaining.

Thanks for your answer.

The 4 pole stators used in these kits have very low outputs at low revs, so will struggle to run a 35W lamp and indicators until high revs.
These stators normally have 2 AC outputs, 1 for lighting and the other for battery charging. Which of these are you using for lighting power.

Hello firekdp,

I am following the VMC schematic for my vespa model. The white wire (lights) attached to the blue wire of the electrical diagram of the vespa.


RG

Ah ok. I take it then, that yours hasn't got the fourth wire for battery charging input into a 4 pin reg/rec.

hello, this is my VMC variable ignition kit, I have installed it according to the diagram indicated by VMC for the Vespa PX model.

That shows the 4 wires from the stator. Normally the yellow is the lighting output , but as they sell it with a Vespa type reg, they correctly use the battery charge output wire instead. This is the higher AC output so that's the best it's going to get, unless there's something wrong with it.

Hello Firekdp, as you say, I could use connecting the yellow cable from the extractor, connecting it to a voltage regulator to have another 12 or 13V and for example: disconnecting the green/grey cable that reaches the turn signal relay (Vespa diagram), instead connect the cable that comes out of the regulator with 12 or 13V. That is, could it be working with two 12/13V supplies: the one with the white cable according to the diagram for VMC ignition PX + the one with the yellow cable as I just commented?

Rg

No, you won't get any more power out doing that. They aren't exactly two separate coil supplies, the yellow is a tapping using about three quarters of the turns @ 0.4 ohms, the white will be the full amount of turns @ 0.6 ohms (values based on idm stator readings).. Whatever, power output from one will affect the other, but white will always be the higher output.

Ah okay, okay, so I misunderstood, thank you very much for this information, it has helped me to better understand the operation of the 4-coil ignition. It is best to put the bulbs of the W indicated for the most appropriate operation. I am going to buy a 25W one for the front light instead of the current 35W one and a 5W one for the rear light instead of the 10W one I have. With these changes I hope the lighting improves. Thank you very much.