Happy with Polini Venturi for 20/20
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Joined: 12 Mar 2010
Posts: 16
Location: SF Bay Area
Fri Jan 11, 2019 1:51 pm quote
So, I've fallen down the rabbit hole called "buy things for Vespa so it goes faster!" I love it, but it's expensive.

This lead me to buy the Polini Venturi for my 20/20 SI carb.

I have the SIP fast fuel tap, Pinasco 2-port 177, and SIP Road 2.0

I have to say, I'm very pleased with the result. The kit came with a 115 main jet, which worked great.

I also got the SIP kit of performance jets (up to 128). They all seemed to work - even the 128.

There was maybe a slight hesitation in revs from idle to WOT with the 128. I eventually settled for the 122.

I've only just installed it. I'll have to check my plug in the coming weeks of riding.

Have any of you tried this? What main jet worked the best?
2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
Joined: 26 May 2013
Posts: 3709
Location: Millbin, Ostrayleea, mate
Sat Jan 12, 2019 8:31 pm quote
Take care to secure (thread tape or loctite) the screw that holds it down... I've heard a few times that they fell out & went down the hole into motor, which is a bad thing
1976 Super (x 2), 1974 Primavera (x 2), 2006 Fly 150
Joined: 26 Sep 2013
Posts: 4284
Location: So Cal
Sun Jan 13, 2019 8:45 am quote
122 sounds about right. With those venturi’s I think a good rule of thumb is at least 10 sizes bigger on the main. Watch the plug and the temps. I used a 122 main (up from 112) with oopsclunkthud’s bellmouth/venturi (similar concept to the Polini) on my 177 with a 20/20 carb. Ran fine.
GT 125 (03), PX 125 (99)
Joined: 19 Nov 2017
Posts: 19
Location: Nr Exeter Devon UK
Mon Jan 14, 2019 12:55 am quote
Best to go massive and work down,. not the other way round,.
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