Modern Vespa

Hoping someone can help/ explain/ ridicule me with an electrical question.

My Lambretta has all of a sudden started blowing lamps after a few weeks riding with no problems.

Last week someone pointed out my tail light was super bright when they were behind me.

On investigation I found my 5w festoon running light and my headlight were blown.

I got home and replaced them, started up the scooter and the festoon blew immediately.

I didn't have another replacement.

Last night while riding my headlamp blew again (only low beam, but that was what I was on)

I noticed my Hi beam was super bright, I mean like super nova bright so I got home with no lights on (it wasn't dark yet).

I just received a couple of sets of new lamps in the mail today but want to get to the root of the problem before I fry everything I have.

Any ideas?

It's all stock 6 volt.

You have a short circuit somewhere. There's probably some bare wire hitting the frame at some spot. Are there any fuses on the vega? Sometimes if they get corroded the resistance can increase to the point where it will eat bulbs. Check every connection for corrosion and then check around bends in the wiring harness and around the handlebar base for worn wires. You can also just test the voltage at the contacts for the bulbs while revving the engine.

Thanks Brooke.

I'm a real dummy when it comes to electrics (and if you ask my wife, oh, nevermind).

There are no fuses, I'm pretty sure of that.

I guess I have my weekend sorted now.

I have a brand new wiring harness, I've had it a couple years but never had the inclination to change it out (a huge PITA).

If it is a short somewhere, would the voltage at the bulb holder be greater than 6v?

I'm not grocking how a short would cause the lamps to burn brighter....

I do believe you though.

thanks,

-marc

voltage regulator has failed completely.. IF it has one.

Old Ducati's didn't, hence the tail light bulb was the link, weak one... check voltage at output wires

The way the wiring worked on old bikes is called a "load balanced system" ..wherin the smaller bulbs like the speedo and pilot / festoon bulb in the headset act as fuses for the system. When one of them blows, the whole thing is off balance and the rest of your bulbs will start popping.

If you're SURE all of your bulbs are good, all the way around your bike ...including your speedo and festoon ... and they are all the correct wattage and voltage ... only THEN would i assume you have a short.

I would also put my money on the fact that the short is actually in one of the coils on your stator versus a wire grounding on the harness somewhere. When the coils get old they can end up putting out WAY more wattage than one wants, and fry out bulbs with ease. I'm watching it happen on a friend's unregulated VBB right now.

Thanks for all the insight guys!

The day after the lamps blew and I'd replaced them a motorist yelled at me my brake light wasn't working.

When I stopped and checked, it was 'working' but flickering on and off in time with the vibration of the engine (man this thing vibrates) so maybe there is a short in the tail light wiring/ brake light switch maybe......

I checked the wires going to the switch but they were tight.

I believe all the bulbs are/were the correct wattage, the only one I'm not positive on is the tail/brake, it may be a 6/18 instead of a 3/15.

The original loom had been repaired over the years, the reason I bought a new one when it became available, so I'll start with that and pull the brake switch and check it.

If that doesn't fix it then on to the joys of repairing the stator I guess

I'm guessing that's a specialist deal?

I do know they are a bear to get out, there is some obscure tool that if used correctly will definitely break something irreplaceable.

Some bodge around it has been devised but not ever having had to do it I don't really know what that is.

Again, thanks for the help, you guys rock!

I'll let you know how it goes.

-marc

You're getting the flicker because the current to your bike varies with the RPM of the engine. They started attaching batteries to bikes to regulate this, and make them more constant ... but batteries add one more point of failure to an electrical system.

Once you figure out which coil is the shorting one ( if that's the issue ) you might be able to just replace that coil ...assuming you can find another ... rather than the entire stator.

And there MIGHT be a specialty tool to remove the flywheel on a vega ..i'm not sure. ALL series 3's require a special puller.

Hey Eric,
yeah the flicker was more than rpm flicker, it was off, it was on, and flicker, off again etc...like a loose wire, it's what led me to the brake light switch in the first place.

There is a puller, it may be the same as the S3, there are a few interchangeable tools (like the clutch compressor).

The joys of using it, and busting stuff, have been documented on the LCGB site

Could also be a bad ground. Check all your grounds. This happened to me with my P - the headlight glowed like the sun, then burned out. I traced it back to a wire that fell off in the headset.

In fact, if your scooter vibrates, that's the first thing I would check. Much easier than screwing around with the stator.

Marc, is your Vega the one with the Starstream engine in it?

Your bike is an AC system so normally on an AC system a short in the lighting wires won't blow bulbs. It'll just make them fliker on and off.

Bulb blowing is normally caused by pulses or spikes of high voltage from the stator plate and usually indicates a bad coil on the stator. You probably need to take a good look at your stator plate.

ET3s have that problem a lot too.

A fix could be to use a AC regulator to regulate the spikes because new lighting coils for J ranges are really freaking tough to find.

Andrea
Edit: BTW if your Vega is the one that was red and chrome with a starstream engine, I really wanted to buy that one, but you got there just before me

Hey Andrea,

yeah mines the one with the Starstream engine, it was red and chrome, on top of metallic blue, off-white and Orbit orange, wow, that was a while ago now!

You just sent me the new bulbs (which arrived Tuesday, with the ST-90, thanks!).

I had a look around the usual places for a lighting coil for a J but they have nothing listed, at least not on the net.

Thanks for the tip an an AC regulator!

I'm replacing the loom anyway, seeing as I have one.

The guy I got the Vega off had another couple, a 50 and a 75 (as well as at least one each of just about everything else )

-marc