Modern Vespa

Hi guys,

I want to commence this thread because there seems to more and more PX E3 owners popping up on MV from Europe and Australia where the PX150 E3 is still being sold. I am not going to go into too much details on how they perform because we all know that they are severely choked up from the CAT exhaust and the SAS unit.

Below is the discussion in Italian that has been discussed since 2011 as there is a huge following in Italy to buy the new Vespa and bring it back to the 80's setup.

http://www.vesparesources.com/13-officina-largeframe/43739-scatalizzare-px-150-2011-e3

So lets start first with the AS IS before we discuss the TO BE model.

When you pull apart the PX150 Euro 3 (cat model since 2011) you will note this jet configuration, which is coincidently exactly the same as my 1986 PX125E arcobaleno that I have in my garage awaiting its turn to be restored. Therefore they have leaned a PX150 to the leaner PX125 configuration because they know that it won't lean out from the choked up induction system.

SECTION 1.0 - AS IS MODEL - THE CARB SET UP

PX E3 Configuration
6823.11 guillotine
Getti : 140/BE5/96
Getto Piloto: 45/140

PX 125 86 Configuration
6823.11 guillotine
Getti : 140/BE5/96
Getto Piloto: 45/140

The below photo shows both my original 6823.11 slide (left) in the new E3 and the E0 6832.11 slide from 1986 (right), giving you evidence of the type of slide you need e.g. no cut outs to lean out the mixture.

wonder if all new spaco/dellorto 20/20 carbs are sold with the new slide?

I can confirm they do because I bought one from SIP advertised as a dellorto but was just a SPACO under licence. When I opened her up she had a 6823.1 slide but the cat version with the cut outs.

I purchased my non cat slide from dellorto UK. This arrived in a packet with PX 83 written on it.

Dellorto handed over carb production to spaco years ago

wonder how many people are running lean and nipping up because of this slide?

did late production px200's suffer from euro emissions?

are the new spaco 24/24 carbs the same spec as the old dellorto's?

my guess is the 24/24 do not have E3 slide.

No . Only in that they stopped making them in 2007

No . Only in that they stopped making them in 2007

There's been discussion here and elsewhere suggesting that those pockets on the top of the SPACO slides don't actually do much except save a few mgs of metal during manufacture. If you look down the carb throat when one is installed, they are only visible and even then only barely, when the slide is disconnected and completely closed, a position it could never be in while the engine's running. At idle position the pockets will have already disappeared and will not vent air from the oval inlet.

Cutouts on the bottom however, if they're there, are another matter.

i'll also add that it is not unusual for Piaggio to spec the same jetting on a PX 125 and PX 150.

I've seen them listed as the same in a few sources that document them side by side.

The Euro 3 PXs also have a different ignition setup to the earlier models. The CDI has a built in rev limiter, which can be swapped for one of these:

http://www.readspeedscooters.com/products/READSPEEDZEUSCDI-readspeed----zeus----vespa-px125-150-cdi.html

Getting rid of the SAS, changing the exhaust and jetting will make a difference but the ignition system needs work too to get things back to earlier spec.

Part of the "confusion" arises from not understanding how a carb actually works. As Rob points out, Piaggio has, on occasion, speced the same jets for a 125 and 150, and the reason is that the two use the same air/fuel ratio and the airflow from the configuration of the two engines is the same.

Rather than retype the basics behind "mixture" I would suggest you read this: Lean vs Rich - Warning! Technical

Note that mixture is by weight. Of course, your carb does not weigh the air and fuel, but uses volume as a proxy.

The carb incorporates a narrowing in the air flow called a venturi. The air supply increases speed through the venturi, and that causes a drop in pressure. That drop in pressure sucks the fuel out of the atomizer. The faster the air flows through the venturi, the greater the drop in pressure and thus more fuel is sucked from the atomizer, within the flow limits of the jet. And that flow limit of the jet is set to deliver fuel at approximately a 13.5:1 mixture.



The speed of the air at a given RPM through the carb of a 2T is a result of of a variety of factors, beginning at the entry into carb box and ending at the exhaust. Change any of these factors and you change the speed of the air flow. If that change in speed exceeds the design flow limits of a given jetting configuration, then you will change the mixture. In order to get the correct mixture, the jet configuration must be changed. So, for example, if you replace a stock cat pipe with a SIP Road, you increase air flow and speed, and a larger main jet is required to provide a fuel flow rate that keeps the mixture at the "sweet spot" of about 13.5:1.

Now move on to emissions, as this is what has given rise to the whole thing. Emission standards are expressed in weight of pollutant per mile driven. Thus the objective is to reduce the amount of unburnt fuel per mile. As stated in "Lean vs Rich" above, a "leaner" mixture burns the fuel more completely ("cleaner") and produces more power, but also has a higher combustion temp. Thus, there are limits to how "lean" a mixture you can incorporate in the engine design to use mixture to reduce pollution, as a too high combustion temp will damage the engine. If a cleaner burning mixture is insufficient to meet emissions standards, then the next step is to reduce the air/fuel consumption per mile, while still retaining the magic 13.5:1. This can be done by restricting aspiration on the intake and/or exhaust side. And, a cat exhaust can both restrict aspiration and perform some cleaning of the exhaust gases.

Also, since there is a limit on how much air, and at what velocity, a given diameter venturi can move the intake mix, the use of a smaller diameter carb can also reduce emissions, which was the case with the US market P200s. Straying a bit off topic, this is the reason for 2 and 4 barrel carbs, with smaller venturis working to each deliver a portion of the air/fuel mix at a velocity and volume that is greater than a single barrel can effectively deliver, but far less than 2X a single barrel.

So, when we change the aspiration by drilling out the air filter or replacing the cat exhaust, for example, we change the speed of the airflow through the venturi. If the installed jets' design flow rate cannot deliver the necessary volume of fuel to maintain 13.5:1, they need to be changed. "Upjetting" is not making the mixture "richer", but keeping the mixture constant, or at least within correct limits.

So, within limits, it is possible to configure a 125 and 150 to consume the same amount of air/fuel mixture per mile, and thus use the same jetting configuration. Obviously, there will be performance impacts, but if the objective is emissions control, in a very simple engine like ours, that is unavoidable.

Lastly, as seen on the Euro 3 Vespas, variable timing can also provide cleaner burning over the RPM range, and a rev limiter can keep the engine from RPM where emissions exceed the limit. But these features do no affect aspiration, the primary topic being addressed.

Make sense?

I've seen a fair few people online buying or using new spaco 20/20 carbs,this was why I asked if this slide could be the cause of heat seizing? aviator/rob hodge??

I've done a couple thousand miles on a Sip road 2,drilled filter and a 103 main jet,plug looked healthy at wot and it ticks over like champ,,exhaust runs alot cooler than the cat one,,everything seems fine

thats not to say it could be doing something I'm not sure of? but if the plug looks good and she flys and starts every morning,does this slide need changing? again aviator/rob hodge?

If your jetting is getting the proper air/fuel mixture, you will be OK. You can have the "wrong" slide and still have jetting that delivers the proper mixture, and mixture determines combustion temp. The slide will affect air flow, but if the jets are correct for the air flow, no problem. You may not get max power, but otherwise, OK. Follow me?

A cat exhaust will, by design, run hotter than a non-cat, because it is oxidizing unburnt hydrocarbons in the exhaust gas, and that chemical reaction releases heat.

not sure if I do to be honest mate,but please bare with me,am trying

are the cut-outs in the slide making the mix leaner by adding more air flow?

simple answer- No. they aren't. they don't come into play when it comes to mixture.

but, even if they did, properly jetting the carb would compensate for that.

honestly, fiddling with the carb slide in this case is akin to picking the fly shit out of pepper.

if you want to make your late spec bike perform as well as an earlier spec bike, you'll need to remove the supplemental air system (smog pump), and replace the catalyzed/restricted exhaust.

unless you change out the barrel you really won't hit the 7000 RPM limiter so the CDI won't be an issue. you'll have to get it over 66 in 4th before you hit that and that really isn't going to happen on an otherwise stock setup unless you drive down a cliff.

Hi mate absolutely delighted you are doing this for us px euro 3 owners , hopefully this won't turn into debate on everything vespa as
there is very little specific information on the forum on the euro 3 ,and having a actual px euro 3 owner that's done the "Scatalizzare"great term by the way ...........wil be invaluable
many thanks, and keep up the good work
george

cheers rob,and aviator

would these cut-outs in the slide have anything to do with the inlet port being 10mm larger on the euro 3 engines compared to old px125s?

also would this larger inlet port paired with a sip road perform better than the old px engines with a sip?

Just to understand my last Q

a euro 3 px has

cat exhaust
7000rpn cdi
12 coil stator
10mm larger inlet port
cutout slide

variable advance ignition

it also has different badges and a different speedometer setup... and those would affect performance about as much as that slide difference.

the inlet port being larger would have much less affect on performance than the timing of it's opening and closing. if the crank cutout is similarly reduced then the improvement would be slight, however if the timings are changed the RPM it delivers power at and how much power would be different.

all in all, i think you are all focusing on the wrong bit here; the earlier p150 isn't the holy grail of setups; you'd be better served by taking what you have and looking what slight improvements it would benefit from rather than what it would take to revert it to a setup basically unchanged since the 70's.

for instance; knowing the spark curve the new cdi has in place and how that can be taken advantage of would be much more useful to improving the bike; it's quite possible with very slight modifications a current spec PX could run circles around a 1985 px, due to the port and ignition changes.

it is very common to manufacturers to introduce improvements to increase power output alongside emissions controls that strangle, in an attempt to offset the hit.

i have a very late Jeep cherokee that is a perfect example of this; while the last two years had tighter emissions that reduced power, those with the earlier spec setups like to get the intake manifold and coil-on-plug setups from the years with the tighter emissions setups because if these are fitted to an earlier spec vehicle, it's a 10-20% improvement in power.

Why add variables , it might ,might not speculation .....he is kindly listing the recipe to Scatalizzare the PX E3
http://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/carburettor-parts/jets-needles-floats-calibrated-parts/si-20-20-slide/

its £16 ............as he recommends it ,why not just change it.... as this is not a general tech question ,i would be interested in how many people actually have a euro 3 px,and are contemplating the changes ,and i hope this
thread does not deteriorate into a general debate on everything vespa and totally off topic and add a confusing myriad of carb,exhaust,jetting variables.

As i actually have a px euro 3 and would like to implement verbatim giramassi,s "Scatalizzare the PX E3"

george

george,,if the inlet port is larger just putting an old slide in isnt putting it back to pre-euro spec

mine does

the problem lies in that there are other slight differences in early and late spec carb castings. simply swapping to a different slide does not reset the carb to an earlier spec. even within the same letter revision of the si 20/20 carb there are noticeable differences throughout the production.

this is despite the fact that these cutouts do not affect how the slide functions in any way, really. its' a red herring.

to put it bluntly, worrying about inconsequential differences in the slide casting while ignoring the fact that there are several other things impossible or expensive to change is kind of ridiculous.

Hi mate this thread was specifically to implement Scatalizzare the PX E3 there are lots of carb,sip2,kits jets,posts on the forum for people to debate

The first part with pictures of Scatalizzare the PX E3 is the slide and the replacement,i,m worried it will just get hijacked with lots of speculation on everything,each part scrutinised and opinions counter suggestions

that's fine on an open question ,but the guys is showing us how to implement Scatalizzare the PX E3 ,put it back to standard pre restriction

he only posted the slide and its followed by reams of conjecture on slides carbs do,s and don'ts , he effectively is offering a specific recipe, not pick and mix
i love the usual everybody sticking there two penneth in ,but the thread is not should i do Scatalizzare the PX E3,or what parts of Scatalizzare the PX E3 should i implement ,its "Scatalizzare the PX E3"

i actually have a px euro 3 and
as someone has been kind enough to offer, a step by step guide ,i had hoped it would be free from the usual "personal interpretation"

I have been told by several people ,that there is very limited knowledge on the euro 3 restrictions on the forum ,so with so few owners of px euro 3, i hoped we could keep this topic simple and focused on the specifics of the changes we need to make and not meander into every other carb exhaust thread
george

but its been proven wrong george

just fitting a slide isnt putting a euro 3 px back to 'normal'

I think this is really important. I understand this thread is simply about trying to go back, but it's not clear that the *right* question is "how to go back" per se

You CANT put a euro 3 engine back to pre euro spec

What Rob is tell us is based on the principles of a 2T internal combustion engine. The way Piaggio reached Euro 3 compliance is not some magic potion, but simply applying those principles. Some changes, as Rob notes, may very well have been to increase power to offset emission control steps taken. Just because there is something new on the Euro 3 engine, that doesn't mean it's a performance inhibiting item. Some emission control steps are minor and are not worth messing with. Others are major (cat exhaust, for example) and that is worth messing with.

As far as the automatic variable ignition timing, that has been a performance boosting feature very welcomed after the days of manual spark advance. I've driven a manual advance 1920s Model T, and can attest to the difference advancing spark makes as RPM increase and decrease. But it sure was a PITA trying to find the proper advance when going uphill.

Just because the Vespa now uses an electronic advance circuit, that doesn't raise it to some modern restricting mumbo jumbo. I would challenge you to tell me how the P engine could use a centrifugal or vacuum advance. This improvement has been long overdue, as the technology has been available for at least 15 years.

What we are trying to suggest to you is to take it one step at a time, so you can evaluate the impact of each item being changed. Change everything by some arbitrary formula that worked for another guy, and you have no idea of what contributed to improvement, no less how much, if any.

I agree with Rob that the principles involved strongly suggest that trying to make a 1980 spec engine out of a Euro 3 is not going to give you the optimal performer. The variable advance alone is a big plus that the 1980 doesn't have.

Unless you know why a change was made, reverting to the 1980 part doesn't guarantee things will be better. Piaggio might very well have found that a given change, such as variable advance, makes the engine run better and took the opportunity to adopt it.

The cat exhaust was not added to "restrict" the engine. It was added because the unburnt hydrocarbons in the exhaust gas needed to be reduced. But to burn (oxidize) those hydrocarbons, the exhaust gas and air introduced by the air valve need to be in contact with the catalyst for a sufficient amount of time. Thus the exhaust flow is restricted to provide this time, not to "restrict" the engine.

So, understanding principles ain't so useless in understanding the Euro 3 engine at all.

Lastly, "Scatalizzare" is an Italian slang word for removing emission control devices that hinder performance. It in no way implies that the end result will be a pre-emissions control engine. Just one that performs better than stock Euro 3 via replacing some components that hinder performance in order to reduce emissions. In short, doing a "Scatalizzare" to a Euro 3 Vespa engine will not produce a 1980 engine.

Good luck with your project.

Hi evaluating each part is a great idea

I have been banging on about just derestricting ,i will be fine with the simple mods he,s advocating i'm aware i cant exactly duplicate the earlier version that was never my intention ,just dumping the cat ,carb mods to retain the smooth running quite bike i have now

I have always been directed towards the "written in stone" sip road 2 drill airbox main jet 98/100" an unequivocal modification ,perhaps the "Scatalizzare the PX E3" mods are considered the same in italy

I interpreted the carb slide pictures ,to be first step of several that he will explain as he goes through the whole process,in itself it may have little effect but in conjunction with the following steps may be critical,

sometimes the smallest omission can have the greatest impact "cotter pin being a good example" Aviator47 you have kindly advised me ,that the euro3 is not as well documented as other variants on the forum , i hoped the thread didn't to get lost in the general discussions and become overly complex and confusing ,before we even get to step 2
george

george

If you google it, "scatalizzare" appears to be an Italian slang term that refers to simply removing a cat exhaust from any type of vehicle, be it a PTW, car, truck, you name it, and making any adjustment to accommodate that, if necessary. Nothing mysterious about that.

If you remove a cat exhaust on a 2T, be it Euro 3 or prior, you will have to check your mixture (jetting). Nothing new there. On a car with an ECU, it's a whole different set of concerns. "scatalizzare" is a generic term, and different vehicles will need different actions if the cat exhaust is removed, and different owners may take it further than others, whether that "further" pays benefits or not. Unless you put it on a dyno, it's all subjective.

That's why I suggested one item at a time. Replace the cat, and adjust the mixture. Odds are you are going to need larger jets. See my explanatory post above.

Then see what that does for performance. If you want to go further, such as the slide, then do that next and see what happens, and so forth with the jet stack, if you feel so inclined.

cheers

Going for an SIP Road and upjet is not "buying into magic" nor is it ignorant of this "scatalizzare" issue. It's nothing more than a more pronounced version of going from a cat to a non-cat exhaust. Frankly, I don't understand why one would believe in the merits of going cat -> non-cat, but approach cat -> SIP Road with a great degree of skepticism. At the risk of oversimplifying the modest additional engineering that went into the Road, the source of improvement from cat -> non-cat and cat -> SIP Road is more or less the same: derestriction.

You don't need to get a Road if you don't want one, I just get the impression you are treating it as either "snake oil" or "more extreme" than it is.

Hi mate if you read what i said i am convinced the SIP Road and upjet is a viable ,valid and obviously popular modification,the only issues i,ve ever had are,is it as simple to do on the px euro 3 with all the differences like the inlet size ,rev limiter ,cdi,slide,ect its obviously tried and tested on pre cat px,s but from the limited info i,ve gathered it not as easy to dial in on the euro 3 ,rough running flat spots bogging ect

I would like to keep the px quieter as my neighbours haven't complained about my early sunday rides like they did with the xs650 lol so the slide,jet,standard exhaust option if its useable seems the best way for me to go.And on the info i,ve received it will be close in bhp to the SIP Road and upjet with just a little more work,

Its really the lack of information on the euro 3 that has made it difficult, I only had confirmation of the different size inlet because a guy actually measured it for me a week ago ,and all the info i got suggested it would be smaller to reduce the fuel mix ,but measured its actually bigger !! i,m a complete novice with vespa,s but my irritating persistence lol is unearthing differences that have surprised some vespa aficionados

so you cant be surprised i,m a little cautious and sceptical on how changes may impact on the changes ,if you get my drift , but with vw cheating
for all i know the piaggio engineers put a curve in the auto advance with a processor that will ejects me from the bike if my carbon footprint exceeds GHG Protocol
,my grandmother used to say "you cant teach your grandmother to suck eggs" but eggs aren't what they used to be lol
george

hydraulic clutch the slide won't fit in the inlet i might try the carb
george

SECTION 1.1 CARB SETTINGS

I will only be providing information as per written by the Official Vespa Workshop manuals. The below are the settings according to the Arcobaleno (PX80E, PX125E, PX150E & PX200E) Modification to the service station manual (Drg. No. 2100378 - Written June 85).

The below image clearly indicate the settings if you want to stick to the manual but from finding a 6823.11 in the 1985 PX125E Arcobaleno, I think you could also try that slide with the same success.

BOOK SETTING FOR PX125E
==============
Main Jet: 96/BE5/140
Slow Jet: 45/140
Slide: 6823.08 (old style without the cutouts)

ALTERNATIVE SETTING PER AUST. DEL. MODEL PX125E
==============
Main Jet: 96/BE5/140
Slow Jet: 45/140
Slide: 6823.11 (old style without the cutouts)

BOOK SETTING FOR PX150E WITH AUTOLUBE
==============
Main Jet: 100/BE3/160
Slow Jet: 48/160
Slide: 6823.1 (old style without the cutouts)

BOOK SETTING FOR PX150E WITHOUT AUTOLUBE
==============
Main Jet: 102/BE3/160
Slow Jet: 48/160
Slide: 6823.1 (old style without the cutouts)

Anybody interested in obtaining the CORRECT slide then you can obtain that from Dellorto UK;
http://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/carburettor-parts/jets-needles-floats-calibrated-parts/si-20-20-slide/

SECTION 1.2 THE EXHAUST

I already own a SIP Road that is still sitting in its original carton but I wanted to not throw any variables into the mix until I had the PX E3 running as they did in 1985.

I would suggest using the original exhaust which is still available in Italy and has a code of 419167 or the replaced model which I have with a code of 15981 which I obtained from Mauro Pascoli in Italy, alternatively you can just use the standard SITO (not the SITO PLUS) exhaust.

SECTION 1.3 FINAL CONFIGURATION

1. Use the jetting and slide setting as per section 1.1 as per your vespa model
2. Piaggio exhaust 419167 or 15981
3. Ensure Timing is set to IT mark for both 125 and 150 models
4. Dial in your carb - Mine is a SPACO and set at 2 full turns out
5. Enjoy your vespa as it should be enjoyed

Once set up you will note heaps of torque in the low ranges without sacrificing the high ranges. I am quite surprised how well this model performs now after the changes and I can confirm it runs better then all 3 PX200's I have owned over the years.

Take it from someone who has actually done the changes in line with what was specified by the Vespa technicians many many years ago instead of debating pointless views based on here say or opinions

P.S. I have not seen any negative impact nor have the countless Italian on the vespa resources forums from the CDI or the inlet port.

Having said that I am going to eventually replace the wiring loom, flywheel magneto witch is currently made in china with the arcobaleno (160884) model as per my 86 PX and the old CDI (185463) so that I can easily swap out my motor with my 86 PX125 motor.

have another go