Modern Vespa

https://www.treatland.tv/polini-CP-21mm-carburetor-with-pull-choke-p/polini-cp-201.2102.htm

This it's clearly payback for me encouraging you to get the 177 and the big box on your vbb. Well done.

Hey Bird… I have a CP 21 sitting in a box on the shelf. Just needs the clamp thing, which you can buy separately. If you want to give it a try, let me know.

Worked for me, along with fitting a nitrile O-ring where the end of the manifold seats in the carb. So far so good.

Ray... pic of your o-ring set up when/if possible?

Mike, you are a prince, a scholar, and a credit to the 50 yard dash. Sadly I pressed the checkout button yesterday before seeing your post this morning.
For now, I am gonna continue to battle to get the 19/19 sorted. If all else fails I will swap to the Polini.

The polini uses the same mains as a pwk. Idles are unique to it and can be ordered in a pack.

You can order the air brake with several different size air holes, it's like adjusting the atomizer to a degree. There are 2 needles, but you probably want the one in it. There are also different slides. I have a whole jetting history on mine that I can share if you want to learn how to adjust.

Here it is:
was 130 DR loss of power - now CP21 jetting

Thanks John. Appreciate the heads up.


I found a jetting chart on the polini site that's a good starting point if I end up using the 21 (matter of when more than if).

Oh thanks! You posted the link before I posted the chart. Great info!

yes, it helps that you are on a stock cylinder with a stock-ish exhaust, that chart will definitely get you started.

( polini 130cc cast iron actually )

meh, you'll have to start modifying then a bit, but the chart will get you into the neighborhood

Sorry, no pics.
I thought I posted one on my 100 Sport thread but no.

I also filled the manifold channels with RTV and replaced the felt ring with another O-ring from my set. Held compressed using leverage and tightened.

I still have the SIP carb with the nylon sleeve on the shelf. I didn't want to go on a jetting adventure with a needle carb, having to release it with every jet change

I'd give the 19/19 the college try just to avoid modifying the throttle cable, or ordering a 90 degree adapter(?).
The Polini jetting specs are pretty much spot on.
Good luck!

Thanks Ray!

Yesterday's college try was a failure. I used chunk of 2x to lever it back onto the manifold. Same leaky results.

I am travel bound through Sunday, but will try adding the rtv and levering the carb back whilst tightening the clamp when I get back.

Scooters are stupid. (Especially smallies.)

That manifold joint just kills me. I have trouble believing that 50% of smallies leaving the factory weren't already experiencing an air leak. How did it ever work?!?! If it used to work, why do so many leak now? It's maddening.

Yeah, it's something that will make ya cuss. I had the same problem on my original 73 Primavera wayy back in the day, but solved it with just a lot of grease on the felt ring. This one, however, is much more ornery.

Has to be one of the top "why?" things Piaggio.
Then again, none of these bikes were made for tuning.

Press-fitting the SF door levers is another one.
Add vibration to those and they're gone.

At least there I'm sure they were tight when they left the factory. They just didn't stay tight over the years.

Tried sealant. Better, but still wheezy. Will rebuild the OG DelOrto today and try that... with sealant.

CP21 arrived, but I haven't sorted a choke modification yet. Also seeing a throttle cable attachment on some that appear more friendly, but so far unavailable on the usual sites.

Battling.

(Was hoping to sort this thing before a bunch of upcoming travel but so far no luck.)

Polini CP21 on a smallie - making a choke cable

Thanks man!
Great info.

I did the same on the smallies I built. Super easy and inexpensive…

Haven't tried o-rings?
I did this in February no issues since. It's important to tighten it while compressed with leverage.

Great snaps, great info Thank you!!!

Waiting for the sealant to dry on the Dellorto.
And then we'll see what happens…

If anything, I am becoming an expert at tank removal, cable attachment, carb removal, etc..

No joy on the OG carb with sealant. Still wheezy. AND… there was an unsettling clack in the gearbox that gave me pause. This build is fast becoming my white whale.

Moby Mobile'

Click in the gearbox is unsettling.
Has also jumped into gear a few times while testing the carb. I thought it was a cable adjusting issue but it happened again yesterday after a cable adjustment and some of the clicks were more like loud clacks.


I know the stack is shimmed to spec.
I am 99.9% sure it is the correct shift dog.
Last thing I can think is that I have fucked up the gear stack assembly? I doubt it… but then I just don't know what else it would be.

I had bought a "unused set, NOS" piaggio gears from a PV125. That is what the exploded diagram says also works in the ET3. I'm at a loss.

I am open to any thoughts, opinions, and spitballs.

Will try and upload a vid if I restart it before I head out of town.

Vid would help.

Quadruple check the shift cable adjustment. It's a royal PITA on smallies. I try to adjust so there's no more than "half a number" slop at the handlebar.

Are you sure You have the correct primary drive (christmas tree) for your gear stack?

I ran into an issue with the last smallie I built, with a strange clicking/clacking sound, and jumping into gear. Turned out I unknowingly had an 50s gear stack, and a Primavera primary gear; which do not mesh properly. The gear teeth dont mesh all the way, and I only noticed after the first start. I hadn't counted the teath on gear stack, and wrongly assumed they were correct.

Since You may have to split again, its worth triple checking the shift dog/cruciform. Later prima/pk type gears are stamped "S" and take a different cruciform than early type. Seems like you are already aware, just thought its worth mentioning.

Fingers crossed it could be a cable adjustment. In that case, I highly recommend following VooDoo's method using bungie cords. This way makes it easy to single handedly setup both cables tight and accurately.

If it turns out to be a primary issue, I have the OG 125 primary out of my Smallie you're welcome to. Just say the word--I'm not using it.

Sorry for the radio silence gang. I have been traveling this week and will be next week as well.

There are a ton of good suggestions here and we will go down every rabbit hole to make sure we get it right on the third go round. I suspect it'll be two weeks before I have any news to report, but will update here as soon as possible possible. Again, thanks for putting your eyeballs on it!

This delay is unacceptable. We need answers! 😀

This ET3 has been a menace but it's worth the wait. Looking forward to pics of this scoot out and about.

OK

Looking for learned smallie expert opinions. SaFiS, Voodoo, Mike, Malcom, Sean, CM, etc

I have a series 2 axle, same as the PK and later ET3s.

Gears are from an OG pv.

I had the series 1 cruciform previously and I am pretty sure that was my issue causing the clacking sounds in neutral. Swapped to the longer gear selector and now everything seems smooth and right except maybe 4th? The gear selector only sits at about 75% of the land on fourth gear..

Can I run this set up, or do I need to get Series 2 gears to run the pk axle?

Thanks in advance !

Not only a purveyor of parts, David is also a life coach…

He should be. He's somewhat the reason you're in this mess! 😛

I say Gawd Damn the pusher man! Haha

Chris would always tell me this when Id send him pictures of stuff he "needed" for his scooter

^^^
Ha!

A little progress Sunday…

Gear stack is rebuilt. Culprit was the wrong cruciform near as I can tell. *facepalm* New batwing installed.

As I started the axils into the bearing the bearing drifted a bit. Tapped it back into place with a drift. Put the back plate on and pulled in the axle. Hoping the bearing depth is correct. Will try and measure and then onwards and upwards to closing up the cases.

yeah it's good to have the backing plate on when pulling in the axle - i've done the same before