Modern Vespa

Hi,

I'm rebuilding a 88 px200 Iris (Spanish arcobaleno), no battery model, 5 wires stator (OG), 3 wires regulator (OG)

Today I did a first start test after complete rebuilt of the engine, runs well.

The only lights plugged are the tail light and the stop light. The front lights are not wired for the moment, just wanted to test the engine.

For a few minutes, the tail light was strong as normal, as the brake light. Then the lights were very dimmed, when I give some gas they sometimes flash as normal and come back to dimmed, these are very fast flashes.

The engine stays smooth all the time, no weird thing related to the lights, idles well, no hiccups.

Also I realized the key has no effect, it runs on off position ! I checked continuity after the key barrel, no continuity on OFF position, continuity on ON position, weird...

The stator is an OG Motovespa, the wires where very old and crusty, I soldered a new loom.

I unplugged all wires from the stator and took measurements

White/green 516 ohms
Red/Green 620 ohms
Red/white 112 ohms
Black/Blue 0.5 ohm.

I don't know how to test the CDI (also OG) and the regulator.

Could it be a faulty regulator ? Stator ? CDI ?

Thanks !

Sounds like a short somewhere or a bad contact. Regulator on my Bajaj was the culprit for dim lights that would randomly come back to normal.

Thanks FINYoshi for your answer.

Since my 1st post I found why the ignition key had no effet, a pin that was crimped but not enough on the wire, on a brand new loom ! I had to de-pin the wires from the massive plastic connector under the nose cover and check, that is done and it works as it should.

Concerning the dim lights, I discovered that I had only max 5V from the stator (AC V measured from the blue and the black wires directly from the stator (unplugged wires from the loom, no problem as not needed to run the engine).

I did replace the wires from the stator during the rebuilt, 1st start after complete rebuilt of the engine no problem for a 5 minutes, then dimmed lights... I took the stator off the bike, all soldered connexions are ok, coils look ok from outside, no burnt wire.

I don't know how to check the coils, I may order a new stator.

I did read a similar issue on the forum, it was the CDI that was the culprit, after the guy changed the stator, the flywheel, the regulator... There was a ground problem with the CDI, but, the engine was running crap when the black and blue wires from the stator were unplugged, but in my case the engine runs fine. That makes me think the stator is defective.