Modern Vespa

Hi everyone,

I have a Vespa Piaggio ET4 125cc 1996 (ZAPM04000) that's giving me trouble when I ride. Initially, it happened when I had a passenger, but now it happens even when I'm riding alone. The problem is that the engine wants to "die" when I go over bumps or ride on a bumpy road. I've checked the intake and the air box, and I don't see any visible faults or cracks. Is there anyone here who can make a guess of what the problem might be based on my brief description?

When you say die , do you mean cut out? If so for how long? I would suggest you start looking at the electrical system which maybe effected by movement. Eg loose earth wires, battery terminals , frayed wires around the engine bay. Check you spark plug lead is not loose etc

Good luck with the faultfinding

Sounds like you are loosing spark. Make sure plug cap is on tight, wire screwed into plug cap firmly, wire has some slack
Also is shock setting correct?

The spark plug lead flexes with rear suspension movement.

Thanks all!

It jerks, as if it loses power, and comes back as soon as it stops moving in the rear suspension .

Thanks for the tips; I will check all the cables.

+1 on checking the cap. It's easy to check as it should snap in place. If you can move it around easily while it is on the spark plug, just replace it. If it's still in good shape, it may just need to to be tighten up on the lead from the coil.