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.