Modern Vespa

i'm getting pretty frustrated. I got this scooter to have fun with this summer and all I'm doing is spending money and working on it in my garage!

After chasing a bit of broken clutch circlip that I managed to find and get out of the gear box after splitting the case, I got things back together and now I'm facing a new set of problems.

1. There is no electrical power. My battery is charged and the horn works but no lights or starter.

2. With the scooter in neutral it rolls like it should (unlike if it is in gear) but when I push on the kick starter while in neutral it wants to roll forward like it is in gear.

I'm about 90 miles north of Seattle and unaware of any shops in the region. I've had horriblew luck with the two most popular parts suppliers unwilling to give tech support over the phone and sending me wrong parts and partial orders.

Suggestions?

I am No help but that '78 P125x I won last fall is now down with clutch/gear problems and this old gal will be taking it apart and rebuilding with whatever new parts are needed. But first I have to build a holder for the front tire, so I can steady the silly scoot and use tie downs to lift it a bit, hang it from the cross beam in my tiny bike shed, so I can remove the rear tire first...I went through the Haynes book and listed all the parts to the clutch, the input shaft and output shaft assembly. I don't have much history on this scooter, but it's over 10,000 miles now and I don't know if any of this has ever been pulled and looked over so I will be doing that and learning as I go.
Last night's fun was packing some small buckets and a box out to the 'shop' for parts and then watching YouTube videos on my awesome (won at work) 54" tv that rarely gets turned on, great way to watch how to take apart and put back together all those parts. I am not promising that it will be together and running by the coming rally. But I am 100+ miles from the nearest Vintage Vespa mechanic help!
Good Luck with your project.

Welcome to the world of real ownership of an old vespa!

In regards to the starter, you probably have some wires hooked up in the wrong place. Go to the diagram and look at the starter and verify the wires are correct back to the stator and all surrounding areas.

Kick start will not work maybe because the clutch is engage. Loosen the clutch arm cable and try kicking it again.

Don't give up. You're almost there.

V oodoo? He has little Vespa dolls on his shelf and knows just where to stick the pins to get them running.

You might want to PM him. He's a cool dude. He might be able to help...

I got this scooter to have fun with this summer and all I'm doing is spending money and working on it in my garage!

Awesome to hear, enjoy reality

For the starter to work, there is one long cable going to the starter itself and an earth that attaches to the case using the flywheel cover screw close to the carb box. For the power/lights, an '05 PX should have a white plug from the stator with blue and black wires. This connects to the white plug coming out of the frame. I realise this may sound obvious, but just make sure the starter earth and white plugs are connected properly.

Did you get the kickstarter gear and the spring installed correctly when you closed the cases, and what happens when you pull the clutch and depress the kick starter? Any resistance or noises?

swa45, those '05 US market PX150's wiring harness i think are different from all the other foreign markets? We got lots of relays hiding behind the battery tray. There's a headlight relay, ignition relay, and of course a starter relay and turn signal relay as well. The clutch safety switch box is located under the horncasting.

I figured out one of my problems - I didn't have the gear selector box installed correctly. At least now I can find neutral and all four gears. Probably have to do some minor clutch adjusting after I get it running.

On the electrical front - I went so far as to remove the fly and inspect the wires on the stator - all looks OK. Yes, most of that wiring is pretty obvious but I'm guessing the electrical problem lies within it somewhere. I wish there was some straight forward troubleshooting procedure for checking voltages at various locations.

Buggering onward.....

Did you get the motor running? See your PM for a little help there. As far as all those other electrical gremlins, I'll bet a dollar the answer lies somewhere here: This sounds awfully daunting to me, a poor guy w/ zero batteries on any of his scooters.

If it was the clutch safety switch I would still get the dummy lights on when I turn the key on which I don't. I keep coming back to that - no indication (i.e., no lights) of power (except the horn).

So many damn relays. I guess I need to systematically check each one.

Stange thing just happened. Out of curiosity I removed the clutch- and throttle-side black rectangular control panels - the ones with the horn, high beams, shut off and turnsignal switches - looked at them and screwed them back in. Then I turned the key on hoping for a miracle which didn't happen. But what did happen is I heard a click down by the battery and found that the fuse had blown when I turned the key on.

Am I on to something?

Not sure what position the kill switch was at.

Yep, you're on to something. Prob a wire is grounding somewhere or you have the wires connected wrong. Do you have a diagram that can be used as a reference to where all the wires you disconnected go? Any chance you took a picture before disconnecting the wires?

I didn't disconnect any wires other than the couple of grounds around the engine shroud and the clearly marked and color coded wires from the stator to the CDI. Thats what is so puzzling.

It's not a complicated wiring system whatsoever.

So am I understanding this correctly that the fuse blowing every time you turn the ignition key on then?

No. The fuse blowing is very intermittent. Its only happened a few times and just this last time I noticed it happening when I turned the key on. I replaced the fuse and turned the key on again and it doesn't blow - at least not for now.

An intermittant fuse blowing isn't good whatsoever. Could you have accidentally mixed up the ground wire and the hot lead to the starter somehow? That might blow a fuse.

Good times. Don't really have a clue where to start.

I'm trying to understand this...does the scooter even run?...either the electric start button or by kicking it over?

Following V oodoo's instruction I disconnected the plastic plug with the black and blue wires and the one green wire that runs all the way forward. So only the three wires going to the stator were connected to he CDI. I push started the scooter and it runs fine (albeit no electrical power).

There aren't that many grounds - the yellow wire off the CDI that grounds to the case, the black wire that grounds to the case and the ground from the voltage regulator that grounds to the frame.

The wiring diagram in my PX150 US workshop manual is fuzzy and impossible to read. maybe someone has a clear copy???

Maybe the fuse blowing intermittently is related - maybe not. But I keep coming back to absolutely NO electrical power when the key is turned on so I'm thinking it is a simple disconnect somewhere - either on a "hot" or "ground" line.

https://www.scooterwest.com/discover-learn/px150-usa-wiring/

Go buy a bunch of spare fuses. Until you know what you're doing it'll help with troubleshooting.

Go ahead and wiggle every plastic wire connector that you can/you touched.

Then make sure every electric contact you can see is secure/clean/tight.

YouTube how to check a relay. There's a few in the picture you posted. There's two that can be swapped and will cause problems so make sure you check one at a time or label them different.

It is very simple, on the US market PX150, there is no power when the key is on. The bike needs to be running. The headlight, speedo illumination, running and brake light, turn signals, and idiot lights are all run off 12VAC power. That means that the scooter needs to be running in order for any of the lights to work. Only the horn is usable when the scooter is not running. There is also a clutch safety interrupter switch on the bike as well. You have to pull the clutch lever in with your hand in order for the starter button to be active.

Here's the Scooterwest diagram so we can all follow along and the PDF you can enlarge to read the fine print: https://www.scooterwest.com/wp/wp-content/uploads/2018/09/PX150-USA-WIRING.pdf

The black box is the HI BEAM relay.
White box is the IGNITION relay.
Green box is the TURN SIGNAL relay.
Brown box is the STARTER relay.
The fuse you have is most likely a 10 amp.
The big heavy box that makes your tongue tingle when you lick it is the BATTERY.

and here's a jpg from the pdf that you can just about read the fine print on

Thank you. I found those diagrams and printed them large so I can read them.

I'm going to test each of the relays per a video I found on how to do that.

I may take a break from all this for a day or two - let the brain dust settle a bit.

I couldn't hold back and had to poke around some more... I may be making progress?

With the black and blue wires coming from the stator disconnected, and the long green wire from the CDI to the kill switch disconnected, the electric starter works and the engine starts but no lights anywhere.

With the black and blue wires connected it starts and all lights except the turn signals work.

When I plug in the long green kill switch wire to the CDI the fuse blows. I know that long green wire goes to the key ignition switch but not seeing how that is connected to or related to the kill switch.

Possible bad turn signal relay???

First off, it's very difficult to understand most of what your issues are with the scooter. Such as, when you were eluding that your fuse is blowing frequently yet intermittent. You still haven't told us if the scooter even runs yet. Hopefully your scooter came with the "operators manual" in the glove box. I would recommend that you read through it. It will describe how to turn on and start the scooter. The PX can be a little more tricky to figure out how to start is because it has a clutch interlock on it.

Even though the signal relay is a solid state electrical relay, it still goes bad quite frequently on the PX150. So it wouldn't surprise me whatsoever if that's why your signals don't work at all.


...and tell us the truth. Did you actually replace any of those common wear internal items that are recommended to change out when you had your cases split? Gear Box Noise & No Kick Start Resistance Because changing out a turn signal relay is easy compared to splitting the cases.

Well I've tried to do a good job explaining what is going on.

There is nothing wrong with the engine rebuild (mechanically). I replaced all of the recommended parts when I did that job.

Yes, the engine starts , runs and shifts perfectly.

The only problem I am facing now is that the turn signals don't work.

I will add however that on occaision, when I turn the key on, the fuse will blow. At least that was happening. I'll have to monitor that to see if it continues to happen.

I purchased a NAPA 12V electronic flasher (EP-34) but the turnsignals still do not work.

I purchased this relay after going through a few. It'll run all LED's or partial LED and regular bulbs. And it works fantastic. https://www.superbrightleds.com/moreinfo/flashers-load-resistors/fl3-red-led-bulb-electronic-flasher/780/834/

You're getting close!

Gotcha...thanks for clearing that up Bhammer. You'll need a 12VAC signal relay flasher. The one at NAPA is 12VDC fasher. This is the one you'll need if you're after an original Piaggio part... https://www.sip-scootershop.com/en/products/indicator+relay+piaggio+for_85036000

Here's what the inside of your PX flasher relay looks like...

What if it looks like this one I found in my misc Vespa electrical junk?

If you can tell me how to test it, I can send it north if it works.

The starter circuit on this particular model has a boatload of interlocks. (I have one, same color even.)

This might help. It's the wiring diagram for this specific model (US market) that I've annotated with wiring color code translations. It's not easy to read. I have mine printed out on 6 sheets of 11x17 paper and stitched together with tape so I can make notes on it and it still takes a long straight edge, a magnification glass, and a fair amount of cursing to see what goes where. I have not yet found any deviations between it and the bike.

Also attached is a photo identifying that pile of relays behind the battery for this model.

With patience, a multimeter (or a cheap automotive test probe), simple circuit troubleshooting skills, plus some more patience, and you should be able to figure out the electrical issues.

I forgot to include this. The wiring is accurate. I haven't confirmed the wiring color labels though.

I put the original green flasher relay back in. Everything seems to be back to normal. The starter works, all the lights and turn signals work, the fuse hasn't blown - yet. Should the fuse blow at some time in the future I will re-visit the electrical system. Thank you for the wiring diagram.

I do have an oil leak that appears to be coming from behind the rear brake plate - where the black plate screws into the case. The oil is showing on the engine side of the wheel. There is no oil inside the brake housing. I did replace the fly side oil seal and I did not take the axle out during the rebuild. Possibly from the bottom of the clutch cover but I did replace the clutch cover o-ring. I'll monitor that and try and determine the source of the leak.

This has been a trying experience for me. I don't mind trouble shooting and tinkering with the mechanical stuff but I find electrical work quite frustrating.

Again, thanks for all the support and guidance.

Great teamwork coming through for the solutions Right On!

I'm still trying to understand what the solutions were

It must have been one or more of the solutions offered or none of them at all and magically it is working, great teamwork!

I have no idea what the solution was. I basically fumbled with the wiring off and on for a number of days and after a period of time everything is working again. Right now the scooter runs excellent. The oil leak was simply due to too much oil in the gear box and I corrected that.

However - I am back to a problem I was having prior to doing any of the work I did. The fuse will blow about every couple of days. This only affects the electric starter and the kill switch so I can run the scooter using the kick starter and all the electrical (aside from the starter and kill switch) works. I know there is an underlaying problem that is causing the fuse to blow but I'm just happy I got the motor back together and everything is working as it should - mechanically.

I hope in time I will find the cause of this problem but in the mean time I'm wop wop wopping around town with a smile on my face.

I believe the fuse blows when I turn the key on. Not every time however. I can use the electric starter and kill switch for a few days and then all of a sudden I will find the fuse has blown.

OK... 95% good ending, but what's got me puzzled is the kill switch being knocked out of service when the fuse blows. I know nothing about the complexities of wiring in newer Vespas, but if the kill circuit is basically just a short to ground via the infamous green wire, then what could the fuse have to do with that?

You have a keyed ignition and a separate kill switch? Key shuts off the motor fine but the kill switch doesn't after the fuse blows? Strange...

Anyway, glad you are riding in this lovely weather w/ smiley face again.