Modern Vespa

I talked to my parts supplier (GPS in Melbourne) about getting the stock slow running jet for my p200 and they said that they didn't have the jet that the Haynes manual listed as stock. What is the actual jet that should be in there?

I have misplaced the piece of paper with the sizes they have available and the book is at my old mans place with my bike, I'll get that info up tomorrow. (been in Sydney all week)

Dad said that on the "Peugoet" forum the Haynes manual is referred to as "The Haynes Book of Lies" Is this true of the Vespa manual?

Wil

Carburettor
Make: Dell'Orto [sic]
Type: SI24/24E (older models may have an SI20/20D)
Venturi Size: 24 mm (0.95 in)

Jets
Main: 116
Diffuser: BE3
Atomizer: 60
Idle SS: 160
Starter Jet: 60


Vespamaintenance.com is a great source for the P2 folk

Yep, don't trust it as gospel... always check with someone who knows.

Keep in mind the idle circuit in the Si carb changed design somewhere after the beginning of the P series run, so most later carbs will use an idle jet with a built in air corrector and will be listed as two numbers, like 160/100.

(edit) just to be clear, I picked the numbers above more for the formatting and wasn't really thinking about accurate jet sizes... for example, 160/100 is not an actual size, it's usually more like 55/160, 45/120, etc.

What is the significance of the two numbers? and what order are they listed?
I didn't get to calling the shop today but on friday he was saying that all the jets they had didn't go up to 160, in the 1st and second numbers.

I currently have a 40/120 but there was so much wrong with the setup I just want to get it right and start again.

(it had 116 main w/o mixer, 40/120 Slow running and a E1 mixer tube, I'd be interested what that setup would be suitable for, just to try and understand how it all works)

I'm hoping the guy at the shop doesn't think I'm after a starter jet? anyway, I'll see what the story is on Monday.

Just to make sure we are talking about the same jet... When you say slow running jet, are you talking about the smaller one piece jet which is not part of the main jet stack? I also call this the idle jet, you can find a picture at this link, as well as all the available sizes:

http://www.dellorto.co.uk/merchandise/products_details.asp?PartNo=9892&CategoryID=2&PartsectionID=69

This type of jet with two numbers is for the later P200 carb design. The earlier carbs had a closed idle jet, and an air corrector in the carb body itself. Later carbs plug the air corrector in the carb body. There was actually a Piaggio service bulletin describing how to make the modification. Check it here, so you understand what I'm talking about, and can confirm that you have the post modification design:

http://www.scooterhelp.com/manuals/VNX1T.VSX1T.service.manual/58.jpg

For the post mod idle circuit you can divide the two numbers to get the relative richness of the idle jet. Divide the larger number by the smaller, the lower result is a richer idle jet, the higher is leaner.

Let me know if that is not making sense or where that takes you... it's kinda late over here.

IMO the way the specs are usually listed is confusing. To simplify I think of it this way:

- Main jet stack= (top to bottom) air corrector, mixer, main jet
- Idle jet

That's usually the only 4 jets you need to mess around with.

I think stock 200 jetting in fun loving countries was main stack = 160, BE3, 116, and then idle jet I'm not quite sure... I want to say 55/160 but I'd like to have that seconded by someone else.

I accidentally removed this post, hit edit not quote.

wil

Just to clarify, or confuse even further, a lot of the old documentation lists all of the jets as hundredths, like the main jet will list as 116/100, the AC is 160/100, etc. That's why some of the numbers look weird in the specifications. This becomes confusing when there is a jet (new style idle jet) which actually uses that format for the jet itself.

I only have old style carbs at the moment which is why I can't tell you what new style idle jet to run. I'd imagine someone here could tell you what is working for them in their P200.

Flip, I'm heading towards confusion!

I'm done with trying to understand, all I need to know is what size Idle jet should I start with in my 1981 P200e.

Thanks HP for your help, I'm on holidays at the moment so I'll try and get on top of it all when I re-start my brain.

If anyone can let me know what idle jet they are running that'd be great, I live on the coast (sea level).

Wil

Hey Guys,

I'm still no further down the road with this one. I am trying to find out what idle jet to use in my p200. I have a 40/120.

The reason I am changing it is because I want to get it back to stock so I can start from there.

At the moment the spark plug is telling me that I am overheaing.

My parts supplier can't make any sense of the 160/100 listed in the haynes manual. He says he needs a delorto part number or something that is on this list.

http://www.dellorto.co.uk/merchandise/products_details.asp?PartNo=9892&CategoryID=2&PartsectionID=69

In a few days time I will be getting a sito+, the current exhaust is a a sito+ that has been opened up at least twice looking at the re welds that are on it, again I don't want any unknowns, I just want to get it back out there on the road, with me on it.

If you have a p200 with a sito+ and you live near the beach I would love to know what jet setup you are running.

Thanks,

Will

Dunno why this thread is just you and me, but at this point I'd say just get the 55/160 and see how it goes.

If you have a look here:

http://scooterhelp.com/manuals/VNX1T.VSX1T.service.manual/57.jpg

...you'll see that the P200E Service Station Manual lists a slow running jet of 55/100, with a note that the idle air hole is 160/100. IMO this is their way of listing a 55/160 idle jet but breaking it into two parts for each section.

If you don't get good idle mixture adjustment and pickup with that jet then come back and we'll figure it out, but that's where I'd start.

You might try posting over at Stellaspeed as well where there's lots of Si carb talk.

sorry hp, my bike is in the shop so i can't pull my stacks to post mine

okay my main is 116
the small one next to it is 55-160
thats totally standard

oh yeh im at sea level and it runs fine
hope this helps

be3 mixer on the main

Thanks Josh, really appreciate it.

Good work HP you were right onto it. I'm still yet to get my head around how it all works, oh well I have my whole life yet.

Wil