Tech Torque: Vespa and Lambretta service guide
PART 3: ELECTRICAL AND GENERAL FIXINGS
Part 3: Electrical system and general fixings
Servicing a scooter is not just about looking after the engine and brakes; it's about making sure everything is in perfect working order…
The general perception of any vehicle is that the engine and braking system are the hardest-working components, therefore they require the most attention. To a certain extent that is true, but that doesn’t mean everything else should be ignored. If you do and then something starts to wear or fail, then unnecessary damage and costly repairs can happen. Just like the previous two articles have mentioned, build up a checklist and regular schedule so you get into the routine of checking everything on a regular basis.
Lighting and electrical system
Lights are the most important safety feature of your scooter and of course, you can’t go out in the dark without them. Quite often they are left unchecked and it’s only when they are required does a fault get spotted. The first thing to do is to make sure before any journey that all the lights are working with a simple check. High and low beam at the front, sidelights (if fitted) and rear and brake light at the back. On the Vespa and some later Lambretta models, also include the indicators. The speedometer bulb should be checked as well but that won’t stop you from riding your scooter, unlike the others.
The bulb which usually fails is the main beam on the front and when it does, it can cause the rear light bulb to blow, certainly on a Lambretta as there can be a power surge through it. Don’t ignore the problem and change it as soon as it happens, certainly at night-time when you have no choice anyway. For some reason, when a bulb stops working some owners fear it is a problem with the wiring but look at it this way – if all the other lights are working then most probably it’s not. At worst it could be a single wire that has popped out of its junction box. Before you suspect anything like that, just change the bulb before anything else to see if that’s what is causing the issue. Wiring can be a difficult subject to understand so do the obvious thing (changing the bulb) before thinking it can be something more complicated.
If all the lights are working perfectly your check is complete and there is no need to do anything else. If a bulb is flickering, then that does suggest there may be a loose connection, and this can be more common
on a Lambretta especially the back-light unit which is more prone to water damage. If you do see one flickering then gain access to the bulb holder and check the connection on the bulb itself followed by the wires that plug into it. Once sorted, make sure the flickering has stopped, meaning the problem is solved. This can sometimes occur with Vespa indicators, usually where the panel locating pin makes an earth contact with the frame. This is more common after washing the scooter or if it has been out in the rain. The solution is to clean the hole where the pins sit by blowing with compressed air to clear it out.
As for the rest of the wiring make sure everything looks okay. Where connectors go into a junction box or regulator, make sure they are not loose or frayed at the end, if so then replace them. Check any earth wires that connect to the frame as they can get corroded on the end. Look at the exposed parts of the wiring loom and if any of the outer casing is damaged or has rubbed on the bodywork, repair it. Finally, if a clip that holds the loom or any wires in place has broken then change it because it’s doing so for a reason.
The two last items of the electrical system are the horn and the battery; depending on what type of scooter and model, they go hand in hand. If you have an older AC electrical system, then the horn works by revving the engine which creates more power from the stator. If the horn works with a simple check, all is fine. If you have a battery system, then the horn will work by pressing its button even without the engine