Vespa Grande start-up w/out battery

Jason Sankey /

Is it possible to start a Vespa Grande that has no battery, supplemental engine stop, or ignition? I'm trying to get this bike to run before dumping a huge amount of time and money into it. I have bought a new spark plug, cleaned the carb, and re-fuled the bike. If anyone might be able to help please let me know!



Re: Vespa Grande start-up w/out battery

it may start by just grounding the positive battery lead to a good ground.

The kill switch wiring should be disconnected.

There's usually one or 2 wires on kill switches that , when the kills switch is activated, ground the one or 2 wires and kill ignition .. (in other words the kill switch somehow grounds the points)


The ignition switch wires are a little different. Usually 2 of the 4 ignition wires function as a kill switch. (Ignition Off = kill, same as the kill switch).

But when key/ignition is turned on, the other 2 wires (probably RED and BLACK) make a connection that allows spark and provides power to accessories. The 4-wire ignition switch has both a normally open (NO) connection and a normally closed (NC) connection. Turning a key changes the status of both connections.. they flip-flop.

So, you may have to at least connect the 2 wires that allow spark. The two others (kill function) should remain disconnected.

But i got a feeling that the thing may start just by grounding the positive battery lead.

Re: Vespa Grande start-up w/out battery

From the picture you posted Jason, it looks like you have the model Grande that has a Headlight/Ignition key switch on top of the headlight. The switch,if it it is there, should be a black plastic streamlined design. If this switch is missing that could be part of the problem.

This switch PLUS the RUN switch on the right handle bar have to be on in order to get spark.

You can make a switch from a nail if you find the right diameter nail. The original switch has a notch on the end where it pushes down and catches. Look at the mechanism inside the headlight casing and you can see what I mean.

The original switch would push down and click into place and had 3 positons, 11 o clock is OFF, 12 o clock is ignition only ON and 1 o clock is lights and ignition ON.

I am attaching a wiring diagram for you. If you look inside the headlight casing at the top you will see all the wires that connect to the main switch plate. It is a bit of a "rat's nest" in there.

If you have to work on the wiring switch plate, the easiest way I have found is to unbolt the headlight and turn it upside down. You should see two openings where you can insert a screw driver and unscrew the two screws that hold the wiring switch plate in the headlight casing.

Once you either get the orignal switch, make one from a nail or wire around it, then you should get spark and can proceed with getting the bike started.


Re: Vespa Grande start-up w/out battery

P.S. you don't need a battery to get spark. The battery is only for the turn signals and is not part of the ignition circuit.

There is a rectifier in the battery case that allows AC current generated by the magneto to be converted to DC and trickle charge the battery when the engine is running. Current only goes in and does not come back out so it is not part of the ignition circuit.

Re: Vespa Grande start-up w/out battery

Jason Sankey /

Great, thanks for the info. I guess the first job is gonna be workin with the headlamp / switch. Thanks again for the help!


Re: Vespa Grande start-up w/out battery

I alao have new and used parts for Grandes jason, but see if you can get spark first then we can talk about waht aprts you need.

Good luck


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