Modern Vespa

did you know the inlet port was 10mm bigger?

Why are you changing the slide?

Asking as ones saying it makes it lean,two others are saying it doesnt?

well, you say there's a 'lack of information' and you're a 'complete novice'.

and you're dismissing out of hand my experience, and my fifteen years working professionally on these machines, dealing with specs most on here have never seen nor heard of. not even to mention my few years working at the LML importer here in the states, part of witch dealt with the emissions modifications for the states, that LML later used to go into europe.

fine. Chump don't want no help, Chump don't get no help.

Go back to the first post, the slide on the right is from my 1986 PX (non-cat) and the one on the left was out of my 2015. I will let you conclude what slide you need to use if you want to run a non cat exhaust.

I am not here to get into a technical debate, only reporting what works, for not just me but for many Italians. The Italians have been doing this set up since Euro2 so this concept is not new or from my hard work.

At the end of the day you don't need to do anything but just keep complaining why you have lag at the first 1/4 turn of your throttle. The lag and roughness off idle is because you are running your idle jet way too lean unintentionally.

I am not dismissing anything .................
I have been posting on this specific subject for weeks and have been given lots of if,s and but,s all well intentioned ,but little with practical application that is an interesting point and the chap that serviced my px said something along similar lines

but its all theorising again "knowing and would"
nothing definitive just if,s and but,s

giramassi is kindly offering a practical step by step guide with no ambiguities,he has actually done................on a vespa px euro3 your quote should have read

Chump don't get no practical help, Chump don't get no help.

I have posted numerous times specifically about the euro 3 and irritating lots of people on the forum with my single mined quest not wanting a louder exhaust ,just let the bike run as it should ,and only now when someone's actually posted a solution ,its all critiquing and scrutinising ,still without offering a practical alternative

I have nut and bolt built far more sophisticated motorcycles,but a novice to the finer nuances of 2 stroke vespas The guy is providing us with a practical step by step application for px euro3 owners only ,as no one's going to retrofit a cat ..............

I rest my case
george

if you look past george's whining you will see I'm asking all these questions to get answers like this above

I'm not complaining of lag or a rough idle though? my euro 3 rwuns better than it ever did now Ive fitted a sip,drilled the filter and changed the main

but its good to have your opinion why you need to change the slide,cheers now i can do a little research and testing on mine with a better understanding about this slide

Hi giramassi just wanted to add,many thanks for you post mate ,and i,m sure the euro3 owners are like myself , are very appreciative of the time and effort you are making on our behalf ,its a breath of fresh air to have something actually practical and i applaud your
attitude, as this is something i will actually do


a chap sent me a message when i stated asking questions george

what part of don't you understand ...............

you have fitted a sip,drilled the filter and changed the mainjust (i haven't got a mainjust)just post another thread where opinions are welcomed, you will get plenty of them,I,ll stop winning and you can debate all you want why hijack whats effectively a fixed thread


george

I think its important to know what this slide does and if it will affect anything if changed,still talking euro 3 remember

Ive highlighed that all new 20/20 carbs come with this leaner slide

Someones telling me ive got lag and a lumpy idle running lean with this slide, Then others are saying it doesnt,who's right? Does this slide make your scooter run lean?

it is important question so post it on an open question
This is exactly what i thought would happen the guys said "I am not here to get into a technical debate, only reporting what works"seem very clear and unequivocal to me ,but if english is not your first language "it means an opinion is neither solicited or required ,if you want to debate this subject just post a new thread ...............
george

The jets ultimately determine the mixture. Mixture is how much fuel is mixed with a given weight of air. Change the air flow, and you use jetting to match the fuel flow to that airflow. Been that way since the carburetor was invented. The slide is not some magical new invention. Slides are configured to get a certain airflow. The different slides may have slightly different air velocity curves from closed through full throttle, but that does not change mixture. Just the amount of air/fuel mix delivered per rev.

Euro 3 is not achieved by significantly leaning the mixture. Lean the mixture too much and the engine seizes, and the stock jets have always been just a bit richer than "too lean" to provide a margin of error against seizing.

his first post was a guide how to do something,I asked a question regarding this guide. are you telling me and others reading they cant ask questions? they need to start a knew thread to ask a question about another thread?

on one hand you want all the information on euro 3s then on the other you dont want to learn about it,why?

youve been argumentative on information you know nothing about,now youve seen something you like you want people to stay out of it without even finding out if this information is correct,doesnt make sense for you not to know if this is right before you do it to your pride and joy. thats the beauty of forums,problem solving,there's going to be mis-understandings and a little upset but a good debate gets results



so who's right,the italians or our resident vespa experts?

What Italians? Just one poster from Australia who claims to be speaking on behalf of every Italian Euro 3 PX owner, based on his reading posts in an Italian forum.

george

Before we go any further, you are not the Forum Guidelines, a Mod nor forum owner. Attempting to set the rules for a thread is a bit presumptuous, and insisting on it is somewhat dickish.

Hi guys i listen and asses all suggestions opinions based on merit not anecdotal evidence,i humbly apologize as i did not intend to break any rules,or overstep any boundaries, i had hoped we could get all the info he was suggesting before he got so pissed off with all the questioning he stopped posting,I am delighted with info he has posted and his pm,s are excellent ,

with so little info or euro3 owners on the forum it feels like its almost a different bike,you are right i have very little knowledge of my vespa px
at the moment but with the spare engine and time that will change.

I do appreciate the advice and help i,ve received on the forum and now feel more comfortable de restricting the bike whilst retaining the smooth running and volume
thanks guys sorry to be a pain
george

George,read carefully

this is the final configuration the op gave on the first page

his euro 3 px125 runs better than 3 px200s,and thats with a standard exhaust he still has the scooter restricted to 7000rpm remember,theres a video from reedspeed on youtube showing the revs jump all over between 6500rpm-7000rpm,they also make the zues cdi so you dont have to change the stator because the ducati type aren't compatible,,,whats opinion,experience,true facts?

he also gives an alternative to a standard exhaust,the sito which is a T5 copy,everyone else advised you on a sip

nobodys taken into account or just dont care that the euro 3 engine has a 10mm larger inlet port? but you seem to be fixed on the slide,how can you go back to pre-euro without welding the cases?

anecdotal evidence put your big wooden spoon down you wind up

I,m aware of the inlet size , believe i may have actually posted the inlet size,a chap measured it for me
but you are right in every respect i am wrong the slides irrelevant i admit defeat,i know nothing ,enjoy your px ride safe
george

No need to spit your dummy out mate,its not all bad seeing as you said you cant touch your px engine or replace it for 2 years

Have you purchased a spare euro 3 engine to turn back to pre euro? You might find none of this applys with your project engine,lol

last time i checked a new genuine piggy 3 engine was over a grand?

This is very interesting to me because I've struggled to understand just exactly what these cutouts are supposed to do. Just to get it out of way I'm going to say it again, the pockets on the top of the SPACO slide don't do anything, but the "cutouts" on the bottom definitely do, basically by introducing a vacuum leak of varying degree across the throttle range. And the #16 slide that came on my Euro 2 bike had 3 cutouts, the big deep one in mid-range and two shallow ones at idle and low range.

Now my question is, what is the effect of altering the velocity curve? In most cases, a slide with a cutout has one of varying depth in the center of the range.
What does this do and why?

Well this is a much debated subject also on the Italian forums but this is what SIP has to say about the subject.

The gas valve restricts the flow of air to the engine . The degree of opening is determined by turning the throttle grip . The further it is opened the more air can flow in . Some valves have air pockets on the top side and cut sections ( so-called ' split ' ) on the underside . These add additional air to the petrol mix and make it leaner as a result . Valves with a flat bottom do not add any additional air and are therefore ideal for compensating a leaner middle range . To be able to comply with the emission values ​​planned for the new PX , the SI carburettors that are currently available are provided with a gas valve with 2 additional air pockets .This attenuates the mix so that partial load pinking and piston jams can occur on tuned engines . The solution to this problem is to replace the gas valve that is equipped with a butterfly valve more often without air pockets (e.g SIP gas valve 04 , No 84,920,400 ) . As of now , the SIP throttle slides are available in versions 4.1 (open 50% of the original size , slightly richer in mid / low range ) and 4.2 ( without opening , the richest of the medium / low range ) also . Conclusion : Throttle valves are often overlooked during the preparation of the carburettor and are the icing on the cake in SI prepared .

I would offer that the SIP explanation is overly simplified, and consequently somewhat misleading.

First, on a very accurate, but humorous note, let me share the words of my Jr High Shop teacher on the subject of air/fuel mixture in a carbed engine. "Gentlemen, if I were to ask you if a too lean mixture was one with too much air or one with too little fuel, the correct answer would be 'yes'". The point he was making was that "mixture" is a ratio, and the real question was which supply element was under or over delivering, or were they both off the mark.

Now on to how a carb works.

In order for fuel to be introduced into the air stream in the carb, the force of gravity on the fuel in the carb must be overcome. That's right, gravity. The level of the fuel in the float bowl is lower that any of the atomizer ports or the top of the fuel passageway feeding a given port. The carb uses vacuum to overcome gravity. Note that the three atomizer ports are progressively higher in the carb, so more vacuum is necessary to get fuel flowing from the "main jet" than from the idle jet. That's the basis of how the "main jet cuts in at 3/4 throttle", becaue that's the point where the vacuum created in the venturi throat is high enough to cause fuel to flow through the main circuit. The carb hasn't a clue as to where the throttle is, just the vacuum that throttle setting and RPM causes.

The slide controls the velocity of air passing through the carb, as well as the vacuum under it. When the throttle is closed, the slide restricts airflow so that the vacuum of the piston during intake is sufficient to draw fuel out from the idle circuit, who's outlet port is below the slide. Thus, for example, there is sufficient vacuum with the throttle closed to draw fuel into the air being inducted. If you try to start with the throttle wide open, the partial vacuum created by the piston is insufficient to draw enough fuel (if any) to get ignition. You could, if you wish, call this an extremely lean mixture. Get the engine running and open the throttle further, and the vacuum is enough to get fuel flowing through the transition circuit, the next atomizer port up the line.

However, the idle and transition circuits can only deliver a certain amount of fuel, based on their "jets" which limit flow, and the limits on vacuum created that low in the carb body. Thus, we then have the main circuit, which has the venturi in the carb body to create increased vacuum, based on air velocity, to provide the next level of fuel into the air/fuel mix. And the main circuit is also limited in flow rate by its jet. The jetting we are looking for in each circuit is that which will be able to deliver fuel at a rate which will result in the proper "mixture". If the jets can't keep up with air flow, the mixture leans.

Mixture is the weight of air to the weight of fuel. Of course, the carb uses volume to approximate weight. You cannot separate the volume of air inducted from air velocity/vacuum and the effect of jetting on fuel delivery rate in each of the three fuel circuits. Thus, the "mixture" is a result of more than air delivery, and the task is to match the fuel flow to the air delivery to get the right ratio.

Thus, my comment above about velocity curves. I apologize for not saying "velocity/vacuum". The slide has a direct impact on air flow and velocity/vacuum. Whether the needs are linear or not in this specific system is beyond my pay grade.

If you think the above is complex, consider that it is still a somewhat simplified explanation.

A bit of an update on some tests performed in Italy on the PX150 E3 including using an exhaust gas analysis machine to determine the different carbon monoxide levels with different set ups. They came up with three configurations that work best with the E3, which are;

All configuration were tested with;
* 419167 piaggio exhaust
* 6823.1 slide (old style stamped INC without the pockets)

Configuration 1
* 140/BE5/98 main stack
* 45/140 idle jet
* Mix Screw 1.75 turns out
* CO value: 3.21
* Fuel consumption 45km/L

Configuration 2
* 150/BE5/100 main stack
* 45/140 idle jet
* Mix Screw 2 turns out
* CO value: 2.82
* Fuel consumption 30km/L

Configuration 3
* 160/BE5/102 main stack
* 45/140 idle jet
* Mix Screw 2.25 turns out
* CO value: 2.57
* Fuel consumption 23km/L

That's quite amazing.

Very interested in this topic since I just got and E3 125PX.

According to the chart Euro3 stipulates a max of 2.0 CO so were getting really close now, at least on the CO levels. Any idea what the HC and NOx were?

Emission Standards for Two and Three-Wheelers

Euro 3 2006.01.01
< 150 cc 2.00 CO 0.80 HC 0.15 NOx

Would you recommend doing the conversion to a brand new bike or is it sacrilege? I'm thinking of waiting at least until the 1000km checkup.

Thoughts?

Also, any idea on what the power difference is on each of the setups?

Thanks for the info BTW.

If you dont care about the warranty. Then I would skip the BS and do the motor justice. I think with the E3 restrictions have lowered these performance wise to toys. Id feel unsafe to ride a PX125 on public roads - maybe in the city where your speeds are usually low - even though power is nice to have on tap for sticky situation. PX125 was already slow and gutless I cant imagine restricted. Rode a friends 2005 PX150. It had the catalyst and it was like an asthmatic smoking a cigar. Put SIP road on and rejetted and it woke it up alot. Now it has Quattrini M1X and a boomstick plus other goodies and its a rocket.

whats Euro3?
who REALLY cares what it is about? you are riding a bloody 2/- afterall!
if you do care, then go but a Prius... ie a completely uneconomical car (when running on petrol) disguised as a planet saver.

I thought: If it aint smokin you not put in enough oil!

I once rode AnaKey from Melbourne to Sydney, & was offered to 'offset me carbon emissions' for the flight home, I politely DENIED this offer, as figured I could not afford to do so.

NOTE: AnaKey was getting 64km out of a tank prior to this ride!

Sorry not sure about the gas levels.

Most people in Italy do it after the first service (1,000 km) and keep all the parts so they can revert it back in case of a warranty claim. I did mine after the first service but went a bit further and also replaced the chinese flywheel, stator and CDI.

For a 125 you will want to replicate my 1986 PX125 I have in the garage by replacing the slide with an old style 6823.11 which has INC engraved on it and have the main jet set at 96/BE5/140 and the idle jet at 45/140 not sure if they are already in the 125 already, also replace the exhaust with the piaggio stock exhaust.

Get the vespa running properly in stock form then if you want you can start playing with performance products like a SIP road etc.

Enjoy your new toy

Thanks,

Thats all Ill do for now I think (once I get tot he 1000km). Already ordered the exhaust from SIP. Ill probably get a 177 kit down the road and do some other updates at that point but ill stick with the jetting, piaggio non-cat exhaust and slide for now.

One question, on the Dellorto website product page it asks for a number 1, 6, 7, 8 or 9.

Any idea what that means?

http://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/carburettor-parts/jets-needles-floats-calibrated-parts/si-20-20-slide/

Number 1 = 6823.1
Number 6 = 6823.6

You need a number 11 but Dell'orto UK does not have them.

You need this one:
http://www.sip-scootershop.com/en/products/throttle+slide+dellorto+11+_68231100

But make sure it does not have the pockets like the one on the left in my photo, the one on the left was from my 2015 PX and the one on the right is from my 1986 PX.

Got it, thanks!

[quote="Dolomite"] Got it, thanks

Just to be sure and because I am total noob but I do have some reasoning powers, can someone just double check this shopping list for the Jets? Might be useful for other noobs that stumble on the thread:

96/BE5/140

96 Main Jet
http://www.sip-scootershop.com/en/products/jet+si+dellorto+96+_40269600

BE5 Mixer
http://www.sip-scootershop.com/en/products/mixer+tube+dellorto+be5+_40417000

140 Correction Jet
http://www.sip-scootershop.com/en/products/main+air+correction+jet+si+_58272000


45/140

45/140 Idle Jet
http://www.sip-scootershop.com/en/products/idle+jet+si+dellorto+45140_40264514

Thanks!

Hi Dolomite

All parts are correct but you might not need them all because you might have some already installed.

Remove your airbox and filter and remove the 2 jets you see on the top of your carb, then just read the numbers on the jets.

I would like someone to post a photo looking down a properly adjusted carb that shows any part of these topside pockets still being visible in the carb throat at idle or greater.

I still maintain they do nothing to alter airflow. The ones on the underside certainly do.

Somebody from an Italian forum actually wrote to dell'orto and received this response.

Oggi, il 27/07/15 scaricando la posta ho ricevuto questa e-mail:

Buon giorno,
questi scavi o unghiate nella valvola gas del carburatore SI servono, a seconda delle diverse dimensioni, a fornire un passaggio d'aria supplementare in determinate condizioni come ad esempio nella progressione.
Saluti
Stefano Prandini
Dell'Orto S.p.A.

Another regular SME also did gas analysis on the exhaust fumes and came to the conclusion that their was a difference between the two types, but I'm no expert on the matter so I will take his word on it.

The pockets do nothing, but...

The cutaway looks to be a different size. It may just be parallax in the photo, can someone that has the two slides measure it?

Best I can do with relative size of the cutaway in the picture:

I suspect Sig. Prandini is referring to the various depths of vents on the underside of various different valves that would fine tune air flow in the lower and mid range.

I'm with Patrick, the ones on top do nothing. There could be other minute differences between SPACO and INC, but I bet those are just mfg slop and worrying too much them is probably, as someone else said, the equivalent of picking fly shit out of pepper.