Modern Vespa

I have a question about my super to all of you guys who know some about modifications, maybe you could help me.
My VBC1T 150 super has a 177cc Pinasco kit.
A Malossi exhaust.
A Polini Venturi kit in the carb. (The carb is a original Dellorto 20.20 like in a 150px.)
A 12v system.
A BGM fast flow tap.
The casing is original, I don't want to do any porting.

Know the big question, what jets do you think I mite need?
some one advise me to start with Slow Jet 40-120 and Main Jet 160-BE3-115.
I just starting my journey with a not stock engine so i have a lot to lern.
if someone know any good Explanations about the size of the Jets i would like to lern.
Thanks a lot.

Hiya, Il Ginchi has a better memory for jets than myself, be also OSS where a link to lots of data & people's set-ups are. i just put in something bigger, then see how it runs over the rev range, & see where it bogs down, or when it screams or where it pinks & adjust from there... But I'm sure others have a more scientific diagnosis than that.
My setup has far larger jets, but that's me...

I'm surprised that you are sticking with the 20/20 carb (& not going to the 24/24) & not doing any porting, but in reality, I don't know how much difference porting actually makes.

I'm coming your way in Sept, so if you need I can bring bits with me, & I've got a jet kit etc which sure helps.

Thanks man, until September I hope the only thing that I will need from you is you taking it for a ride and tell me
What you think
let me know when you have dates.

Love the colour, the guys did a great job... I did have my doubts on them.
Can't wait to have a ride

Start with the jet that comes with the venturi... from memory it's a 140... then work down from there. The venturi make a BIG difference to the amount of air the carb can flow.

http://lfs.alexander-hepp.de/

Pick english top right, then 177 from the drop-down list on the top left, then scroll down to Pinasco. Lots of setups to compare!

I knew you had th skills

non of them fit my setup. wired.
i will start with that and then look how it goes.
any tip?
thanks.

Find the closest setup in that jetting database, go a little richer than that and work down would be my suggestion.

Oh, and once you're done, add your setup to the database to help out the next guy.

You're right, there doesn't seem to be any with a Polini venturi. If I was you, I'd start with a 55/160 idle jet, 160 ac, BE3 and the 140 that came with the venturi and see how you go.

I'm running the 140 or 142 with a similar setup & it seems pretty good. I STILL cant go WOT in 4th, but need to change the tap & then chuck it on the Dyno to find out whats happening

don't worry, after i will finish the tuning i will update on the database. i just checked, the main jet sould be 140 as you say.
it sound very big, but, what do i know about it so i will start with Slow Jet 55-160 and Main Jet 160-BE3-140?
thanks a lot!

Its pretty cool saying... Ive got a 177 & use a 140 main... What do you use? ohh, Mines BIGGER than yours!

Well I checked, the Venturi kit for the 20.20 carb comes with a main jet 115.
The kit for the 24.24 comes with a 140.
So I think I will start with 115 and see where it goes.
Let me know if you have any ideas.
Thanks.

Do you have a CHT gauge?
They are well worth the investment. There is a nice small one (so eone will have a pic).
Keep am ear out while riding, listen to the motor, start with 115.

Yes I have one.
I have one on my SS as well

Do you recommend those TTO gauges?

I didn't try anything alse but I have it on my SS for something like 4 years. I like it.
It gives you the temp in each moment and the max temp that you reached.
It's small and elagant.
If you have any specific questions fill free to ask.

yip, they are almost essential (when you order get enough extension wire), ive watched the temp rise 50-150f over a few hundred metres, & there is no chance without it that you could pick that something has just gone wrong.

115 seems pretty small ...

SIP recommends increasing the main between 10 and 15 sizes if you're running the 20/20 venturi on a kitted scoot.

I'd start closer to 130 to be safe.

The original main jet on the super (2 port) is 88 on 15.20 carb.
Still think I should try 130?
Thanks.

A jet costs what, $5? And what does it cost to repair a seized kit?

Still think you should try.

ok thanks.
i am buying from sip 105-108-110-112-115-118-120-122-125-128-130-132-135-138-140-145-150
one of them will do the work.
if you could tell me how i should test it would be great, first time i am doing that.

We have set up similar to yours and run a 112 without a venturi. The venturi should flow a lot more air, so yes, 130 should be a safe place to start. As a matter of fact, we've got a bell mouth in the garage waiting to be installed. Just waiting for a box of jets to get here.

As for testing, if it bogs at WOT, you're still rich, drop down a jet. Feel and listen to the engine.

S I P have a 10 pack of jets, well worth getting ,then you can play all day long (or in my instance all year long) with jetting

Where's the best/cheapest place to buy the gauges? I want to fit a temp gauge and a rev counter to my build.

Ideally, you'd do it on one day so you don't forget what a particular jet feels like. Start with your richest jet and do a short loop near home, paying attention to how it feels. If it's too rich it will "bog"... it feels flat and when you open the throttle pretty much nothing happens, or it will pick up speed very slowly. It will sound like blaaah rather than zing.
Go down in size jet by jet until it stops bogging.
After that you can do plug chops, but that's another story....

Where you get them guys?

http://www.trailtech.net/digital-gauges/tto/temperature

http://www.ebay.com/bhp/trail-tech-temperature

http://www.amazon.com/Trail-Tech-Temperature-Meter-72-ET3/dp/B0031BIWX2

Remember to get extension wire

http://www.trailtech.net/digital-gauges/tto

It's what a lot of us here use. You'll find them on ebay as well.

Mucho gracias

Finally got around to photographing my CHT gauge. It's a bit cool this morning! The wire has been extended and feeds out through the bottom hole in the spare wheel via a connector which is small enough to fit through that hole if the spare is needed.

The biggest one I have is a 140 main, and it seems to work really well. I have the jet kits from SIP to experiment with. I soft seized once using a 125, so I'm not taking any chances. Our set up is very similar.

VLB1T (2-port motor, ports on cases left original)
Pinasco 177, iron cylinder, 2-ports
SIP fast flow tap
SI 20/20 carb (drilled passage in float bowl approx 2mm wide (FMP recommends 2.5mm)
Venturi
original air bellows (no foam filter)
Pinasco large volume carb cover
SIP VAPE 12-volt ignition (18 degrees)
Premix 3%

This setup seems to work well. Spark plug is black, yet clean, not sooty.

Try big main jets that bog/stutter the engine at WOT, and then downsize until it doesn't bog. The performance should improve as your mixture becomes leaner.

if I were you, I'd pick a richer setup that runs all day instead of something that makes peak power. It's worth it for peace of mind.

I'm still learning this stuff myself. Your experience may be different.

Have fun, be safe, and try not to waste too much money!