PWK-type 28/30mm Carb

Hi everyone,

Has anybody had experience with this Carb:

PWK-type 28/30mm Vespa

Ive just ordered one but after reading all the comments on here regarding jetting and set-up etc I’m wondering if I should of just stuck with my 26/26.

Has anyone set one of these up before? Im running a 210 malossi, ported crankcases, racing crank, lightened flywheel, cosa clutch & Simonini. Will this carb make a big difference? Are they in need of constant attention?

Cheers jimmer


I don’t think Vespadoc has your set up, 140 main generally is used with reed intake.

I don’t think with your set up and exhaust you would need bigger main then 130… maybe 132 as absolute max…maybe
if I understood well you are not running with reeds…
You know you should try and see how your engine feels.
The slow jet it regulates the idle and the transition from idle to the first part of throttle. Finding the right one in normal stroke is not that difficult, much more difficult with longstroke, at least in my experience, if you want have a regular iddle and good transition to 1/8 of throttle.
If your carb comes with 40 start with 40 it could be ok in your set up.

The needle position mainly effect the rage from 1/4 to 3/4 of throttle, mainly since when you change the clip position you will feel it also in the lower range.


I would put then a 130 main, iddle 40, needle clip in 3rd position from the top, air screw 1 out
and give it a try to see what is ok and what needs to be changed

Top man the doc thanks!

By the way I was wondering if you were the same Doc as on the Revival Scooters Web site - Ive ordered parts from you guys during my last build - Now I know!

Do you happen to know what main jet you are runing with your 210? - Just so I have a benchmark to start with?

Thanks again


yes i am the same doc as on the revival website and my main jet is 140 with 100 idle jet

Thanks chaps!

I’ll have a play this weekend - Ive ordered spare jets from 122 - 132 so hopefully set-up won’t be that difficult.


I constantly use keihin carb and I can confirm Doc impressions.
The only other carb so good are the Mikuni TMX but they have a much bigger body.

You asked for a standard set up.
I will try to give you one but I have to say that I always mounted it with reed intake so not experience with your set up, but I would say:

Main : 128 (get a spare 125 and 130)
slow : 42
needle: JJH (start with the needle clip in the 3rd position from top)
Slide: 3.5

hi jimmer, i have one of these on my 210 that i use on the road and for sprinting. it was recently dyno’d at 100mph kicking out 23.8hp and revved to 10750rpm so i’d be happy to say they are a doddle to setup and are way way better than any dellorto. any queries contact me at revival scooters
the doc

Thankyou Curare,

I have ordered a jetting kit with the range based on a 128 main jet.

They only had a size 40 slow running jet - will this be a problem?

Is it as simple as if the engine ticks over then the idling jet is the right one? Excuse my ignorance please Ive only ever used standard carbs on all my scoots!

With the main jets is it just trial and error to see if she pulls all through the rev range ? And the needle position - What rev range does that effect ?

Thanks in advance everyone.


Thanks - I’ll do that

Thanks Vespa Doctor,

May I ask if your set up is similar to mine above - If so I had better some larger main jets!

The new carb hasnt turned up yet & my 26/26 Vespa original style carb currently runs with a 128 main jet and the engine pulls well (Although it hates starting & cant work out why!!) - Is there a link in jet sizes across the 2 carbs?

Thanks again