Modern Vespa

Few days ago I accidentally picked up another Vespa.
It is 1984 PK 50 S (V5X2T) which stayed few years on the open air. As far as I know the previous owner had it for 12 years but scooter never was in good shape.

I always like look of pre-XL PK's. But the main advantage is that this PK S have all papers and a number plate.
And I also have PK 50 Nuova without papers but with freshly built engine and front fork assembly.
So Nuova again sacrifices herself to give life to another Vespa.


First time I see it on 30 May, 2020.

First time I see it on 30 May, 2020.

First time I see it on 30 May, 2020.

First time I see it on 30 May, 2020.

The day I picked up it - 03.02.2023

The day I picked up it - 03.02.2023

Gave it some attention, take off weird stuff, clean it a little.









It's outrageous - only 1 km for three years!

I decide to call it the Snowball.

V5X1M ?

With new friends in dry garage.

New spark plug, bit of fresh fuel and here we are! Was really surprised that all lights and turn signals works. Ride on it a little - clutch is terribly slips, gears change ok but seems too short so I think maybe it have something bigger than original cylinder.

Neat find!

"accidentally picked up another Vespa."

hell yeah!

pre-XL PK's are where it's at.

your rear signals and tail light look slightly different than mine, I'm guessing it's just a market difference or maybe because it's a 50

you're gonna want to take off those foot pegs immediately, they're total ankle biters!

Yes mate maybe I said it wrong but my english is not very good.

Few years ago I already offered to buy this Vespa and later I asked again, but the owner categorically did not want to sell it, saying that he would repair it and ride.
So another three years have passed since my last proposal and he called me and offered to buy. Of course now is not the best time to buy, but I couldn't resist the great price. He called me on Thursday, and on Friday I went to pick it up.

Tail light is original and it have no stop light. And rear blinkers is not original, it have wires solded to bulbs and bulbs hanging on zip ties.

It seems that it have combined 6V and 12V electrical system - turn signals have 12V bulbs but rear and front lights have 6V bulbs.
And now I'm a little confused because I want to put in motor with original PK XL 12V ignition and I don't know if it will work correctly with the original wiring of PK S.

It have no high beam - only running and parking light. The high beam indicator have original plastic blank on the bulb place.

I also think that this PK S had no speedometer but plastic blank when it came from the factory. Thats why it have 125cc speedo and no wires to speedo light.

And the first what I done - removed that weird PX crash bars and foot pegs. Maybe previous owner likes how it looks... But the main problem with it was that you can't comfortably kick the motor.











Last edited by roland87 on Mon, 06 Feb 2023 14:43:17 +0000; edited 1 time

So the question about electric scheme. All this electric things and wires harness is nightmare for me.

Hope somebody can help me. I want to use PK XL 12V ignition(I also have CDI, voltage regulator and indicator relay) with PK S wiring loom. Will it work straight or I need do some changes?

Here is electric diagram of my PK S

\you said it perfectly.

I love the "accidentally picked up another vespa" line. Always a good excuse. Great little find.

As I was a lot of enthusiasm I wanted to do at least something.

As Snowball was left in friend's garage I came home and start to tear down Nuova. Taked off front fork and engine.
Next day I put Nuova frame in my car and go to friend's garage. Taked off front fork and engine from Snowball.
Left Nuova and Snowball fork in the friend's garage and go home with Snowball frame and engine.
Then put Nuova's fork on Snowball.

From my knowledge of PK wiring, its a nightmare. Rather than put the PK XL engine in with its current flywheel and stator, could you swap and put the PK S stator onto you rebuilt engine. I guess its all down to if its a 19 or 20 mm cone for the flywheel. Or would either flywheel work with the stator.

Excellent tip! I don't think about this way as I thought that PK S have 19mm cone. But I don't look at it yet.
On other side 6V headlight is very dim...

Its got to be worth having a look. Its all down to if the PK S stator will work with the PK XL flywheel Could you make it rev harder

4-pole stator not compatible with 6-pole flywheel, I tried it on another engine. If I'm remember correct it rubs one another.

Looked at PK S ignition closer and realised that flywheel for small cone.

And I remembered one small but important moment - on my PK XL engine crankshaft is with small cone too! The PK XL flywheel mount on it with Crimaz adapter.
So puzzle is done and I will go by advice of Matchlessman and try to use PK S ignition and look how it will go.

Thanks again mate!



Last edited by roland87 on Fri, 17 Feb 2023 21:48:35 +0000; edited 1 time

I also made photos of... voltage regulator and indicator relay???
It is totally mess and madness. But this shit works

And on the next step I changed primary cog from 19T to 21T on the PK XL motor.
Gearbox was very short with 19/60 but for off-road riding it was perfect. I use gearing calculator and it seems that 21/60 must be ok for road usage with 3 speed gear box. I also have 20T cog if 21T appears too long.

Removed the flywheel(yes it is for small cone) and was surprised how nice and clean the stator looks.

that's the best part of all of the electrical you've shown!

Looks like a capacitor was used with that regulator rectifier in order to store up some 12VDC power?

100% ! I'm very bad in electric questions. All I can saw that on the original electric diagram of my PK 50 S there is no any capacitor or voltage regulator - only indicators relay and Bizener(Zener) diode... NIGHTMARE

Had few hours today that I spent in my garage.

Changed ignition on PK XL engine from 6-pole to 4-pole.
And noticed that 4-pole ignition not works with PK XL CDI - it gives sparks only two or three times when kicked and then nothing.
So I put CDI unit from PK 50 S too.


6-pole out.

4-pole in.

Fresh wires and connectors.

4-pole ignition works only with this orange CDI.

I had to drill one additional hole on the CDI bracket.

Hope all will work proper.

I realised that I have no decent exhaust for this build. I can't use Polini Banana as it needs lot of frame cutting because it was for V-range Vespas.
I will be use terrible original exhaust for some time with this SIP stainless steel manifold. Hope it gives a little more power.

Can somebody help me with advice about glove box lock?
On my PK 50 S it looks like after bad repair and works terrible.
I understand that I need buy new cylinder lock and new button and other parts. But I can't understand what exactly I need. Maybe somebody can give photos of lock mechanism or link with it?

I need to buy:
1.Cylinder lock
2.Press button set
Is it enough or I need some more parts?

Here is how lock looks on my Vespa:

Some good news. My friend found his old exhaust which was mounted on his PK when he got it. And now he presented me this exhaust.

Seems like Leo Vince Secsys but have different muffler and have no upper muffler mount.
For sure this pipe saw better days but also for sure it will give better performance to my engine than old original pipe.

I also was surprised how easy and right on it mounts on the engine. Much better than brand new Polini Banana which I mounted on few PK's. I even can put in/out wheel without deflate it.

that seems like a good design, do they still make them?

I gave up on finding a new (or used) Secsys exhaust many years ago for my PK125. I specifically wanted that pipe so that my spare tire would fit. But alas, that pipe wasn't in my cards.

Someone should copy those.

Do Leo Vince was make Secsys for 125cc? The more I googled about this exhaust the more I want one.

Not quite the same but simonini have this one.

https://www.sip-scootershop.com/en/product/racing-exhaust-simonini_40300300?cr=3a6304bb-cc81-4ed5-9f63-1ff45fe1abfa&gclid=EAIaIQobChMI09ndjN-c_QIVTNPtCh00BQ6YEAQYASABEgIGtfD_BwE

The links for the one for a 43mm stroke but they do the 51mm stroke as well.

They made a 50cc version and a 125cc version. I did find a NOS 50cc Secsys about 3 years ago (online overseas), but i would have had to do some modifications to it to fit my 125 cylinder, so i passed on it.

Before I get this Secsys pipe my idea was to buy SIP Road Banana 43mm stroke and then in future when/if I want go to 130cc just buy only SIP manifold for 51mm stroke.
I emailed to SIP with question about compatibility 43mm stroke exhaust with 51mm stroke manifold and they replied "Yes".

But on the other side is my sad experience with Polini Banana - I try 43mm stroke exhaust with 51mm stroke manifold and it was a failure.

BTW today I have few good hours with Snowball.


Changed all cable sleeves and mount a rubber grommet.

It is really easy work with long enough spare cable.

Old sleeve out - new sleeve in.

Mounted brake pedal from my PK Nuova.

Small diner.

Fresh air bellow.

Cleaned a bit inside chassis.

One of centre stand springs was wrong...

...so it worn out the stand mount...

...and spring mount hole on the stand.

And removed that terrible tractor-style indicators.

what will you do with the indicator holes? or do you have different indicators to use?

I want to put original or repro(but model correct) indicators.

Have you seen this Simonini pipe? I had a Primavera I put one on and it did a good job for me. Tire changing was actually pretty easy w/ good access to pull the swingarm bolt, then just swing it out on the header pipe joint, twisting the retainer springs a little.



Here it is on my first USA bike:



Also Leo Vince has a decent pipe I got for my PK that I later cut & modified for my older smallie.

On the PK, I got a killer deal from the shop of a friend. It fits nicely up in that muffler cavity underneath that older smallies don't have:

Yes saw them. But don't like how they look and finished - too rude and, for my PK S, too race . Never hear them in live but read a lot about the too loud.

So in not near future I think about SIP Road Banana or new Polini Classic
I put the last one on my mate's engine and was really like this pipe - very accuracy and hight quality product, mounting also perfect.

Good progress today:


Engine in!



It was really hard to do swing arm bolt on exhaust. But done at least.



Fast flow tap from my Nuova.

After mounting carburettor I noticed that there is very little space between air filter and chassis seam.
In the static I can't them do to hit one another but there is really very close.

On my Nuova there was no same problem - the seam looks a half smaller and I also think that upper rubbers of shock absorber was in better condition.

I try to sort it tomorrow.