Modern Vespa

My mate gave me PK for engine mounts and steering bearings change and some other works.
I changed engine mounts and threw engine back.

And noticed that ignition lock not working. There still a spark on the plug when lock is turn to "OFF".
Ignition is Vape Road, almost new, only 2000 km done.
If I add ground wire between engine and chassis - all works as it should.
The same problem is on my 50 Special with same ignition. But it appeared after near 10000 km and few years since ignition was installed. And also after engine was took from the chassis for rebuild.

I also noticed that SIP sell ground wire for Vape ignition so maybe this is well known problem now?

I can only assume that it's a problem, what i can't say is if it's a well know problem. Seems like having a CDI that's mounted through rubber bushings is going to be potential for a possible failure. Poor grounding is ALWAYS going to be an issue with anything electrical. For all of my scooter builds i will add in a few extra grounds, one from the CDI to the engine block, another from the block to the frame, and another from the headset to the frame. I usually tack weld the head of a M60x20mm screw to the frame so that it can be a grounding lug (both at the front and rear of the frame.

Roland I second whodat. Rubber mounted engines need a dedicated ground to the frame. Even rigid engines need a metal to metal contact to work correctly. On all the engines in the planes I work on we make sure there are two separate grounding points for redundancy.

Rob

I'm absolutely understand you guys.
But all was work for some time on both scooters without any extra wires...

Agree with the gents above. Some extra ground points are a good thing. First pic CDI is double grounded to engine and second pic engine grounded to regulator / frame / battery...

It definitely works with the brown cable from the vape stator.

But I think it might not be enough.

Vezzola CDI mounting kits come with a dedicated ground. I've never brought one, but seems like a great idea.

I've added a ground, pretty much what the SIP cable is… 13awg if I remember right.

I'm not sure if a ground from the frame to the engine matters… never seen that before on a Vespa.

In the past few months I've seen people mention issues - like poor running, spluttering - that cleared up once an earth wire was fitted.

Here are pics of the multiple grounds on my blue Allstate 12DC vape harness. I'd like to think i'm well grounded.

Just like my mother would yell " You're grounded, Mister!! ".