Help me reach ~40 on my Vespa Grande

Hey friends!

I am new to this site, but it seems ROCKING. I have a 1980 Vespa Grande Piaggio. I just took it out of storage and tried to get it running. I put some gas in it and it started right up. It was running well and I was able to cruise around for 15 minutes. After that, I parked it. 10 minutes later I tried to start it again, but it didn't want to run. It might run for 10 seconds now, at low power, and then shut off.

Last summer, it had a problem with leaking gas. It would empty its tank over night. After replacing the fuel line, it still leaks gas. I guess it may be something with the carb or the petcock?????? Anyway, I'm interested in modding it, so I can hang on the 30 mph roads around here. I'm shooting for close to 40 mph. Right now, when she's running well, she tops out at about 25 on flat ground.

I am looking for the easiest performance mods to get me up to 40mph.

From Zippy, I have picked out:

-Carb, DellOrto SHA 13/13 -Will this fix the leaking gas problem?

-Exhaust, Sito Plus OR slightly more expensive Polini Marmitta Exhaust

-Air Filter, Malossi Performance

-POSSIBLY -- Variator, Polini performance

Should I get a 43mm "kit" too?

AND, I am looking mainly for easy, bolt-on mods if possible. I am only fairly mechanically inclined.


Vespa is leaking gas.

Goal of close to 40mph top speed.

Will Dellorto Carb 13/13 fix this?

Which exhaust is better, the Sito Plus, or the Polini Marmitta?

Should I get a Polini Performance Variator?

Should I get a 43mm "kit"?

Other suggestions?

Re: Help me reach ~40 on my Vespa Grande

Get the 13.13 and the Malossi filter, but dont get either of those pipes. Get a Simonini Circuit exhaust from Dont get a kit unless you are comfortable taking your engine apart. Get a Polini or Malossi variator and belt.

Re: Help me reach ~40 on my Vespa Grande

Alright! Thanks for the reply.

That has a lot of parts, but every single one I wanted is out of stock, including the exhaust you recommended.

OK, so new list:

-Simonini Circuit exhaust

-Dellorto 13/13 Carb

-Malossi air filter

-malossi performance variator

-New belt/pulley

Also, I've seen a lot of posts involving "jets" or "jetting." What is that? Will I have to do that?


Re: Help me reach ~40 on my Vespa Grande

JamesG is right about the exhaust. The polini is better that the Sito but it is not that great. It looks like they have the Circuit exhaust in stock right now. But youd be better off if you wait until you can get something better.

Re: Help me reach ~40 on my Vespa Grande

sorry I meant to say "it looks like they Don't have the Circuit in stock"

Re: Help me reach ~40 on my Vespa Grande

I was going to say....

You made me check again, haha.

So, you say the Simonini Circuit is no good? What should I hold out for that's better?

Re: Help me reach ~40 on my Vespa Grande

I'm sorry, I should pay more attention to what I am typing.

The Simnini Circuit is a good option. Better performance and is a few $$ cheaper priced than the Polini you mentioned getting from Zippy. But is out of stock right now.

Here check out this other Post all about Vespa Exhaust :

Re: Help me reach ~40 on my Vespa Grande

Yeah, I found that post through Google, but had trouble loading it before.

That page REALLY likes the Simonini Calibretta.

Simonini Calibretta. in their words:"this pipe doesn’t ever like to walk. it’s always sprinting!" the proma-gun is good, but the calibretta is better! low mid, super super fast high end. probably one of the best.

It's close to $200. Is it really worth it?

Also, I've heard lots of praise for the Proma Circuit but that seems like it's impossible to find.

Re: Help me reach ~40 on my Vespa Grande

Hmmm, actually does have the Puch Proma Circuit in stock? Will that fit on my Grande?

So, Proma Circuit vs. Simonini Calibrata............thoughts?

Too many decisions!

Re: Help me reach ~40 on my Vespa Grande

Allot of the higher end pipes are for kitted motors. You may not ever get the power from a pipe like that if you are running a stock 50cc cylinder.

Re: Help me reach ~40 on my Vespa Grande

That's what I thought. What about the Puch Proma Circuit? Would that be good for me?

Re: Help me reach ~40 on my Vespa Grande

Puch's exhausts mount different than Vespa's. Wont work.

Puch bolts on with a flange on the header, Vespa is a pipe clamp style mount.

Re: Help me reach ~40 on my Vespa Grande

I have basically the same setup and can hit 35 but I have the stock variator and wrong belt. I bored my carb out so it's not as good as a real 13.13. I have the techno circuit 2 and like it ok. it's not restricted like the original. You should be ok on the 66 jet that comes with the 13.13

Re: Help me reach ~40 on my Vespa Grande


Re: Help me reach ~40 on my Vespa Grande

Polini top one and Sp are good. Simo circuit interfered with my peddle sprocket, I can't hang with that, I'm keeping my pedals. I think its gonna take some porting and crank cutting to get the stock cylinder past forty.

Re: Help me reach ~40 on my Vespa Grande

I'm having a hard time getting my kitted Bravo to the 40 mph mark. I think it'll be very difficult to get there on a non-kitted bike.

My specs (38 mph):

43mm Polini Kit (case matched)

Modified Factory Crank

Dellorto 13.13 Carburetor (64 jet)

Malossi Air Filter

Malossi muitivar

Polini Top One pipe

Re: Help me reach ~40 on my Vespa Grande

Your Bravo is probably held back by that Polini pipe. There is no reason that setup should not be well above 40, especially on a light Bravo.

Ed, they do or did make a Proma Circuit for Vespa's. I have one sitting at the shop waiting to go on a Ciao, but I havent run it yet and don't know how good they are. I would go with the Simo Circuit, I think the Calibrata might be too aggressive for your stock cylinder, as was mentioned.

You will definitely need to rejet when you do this. This means swapping out the main jet in the carburetor for a larger or smaller one. This is crucial to tuning your moped correctly making it run right, and you must understand the how and why. I'm sure a small book has been written on it, but basically larger jets = more fuel, smaller ones = less fuel, which, given a constant volume of air, means richer or leaner fuel/air mixture, respectively. This mix is what is pumped into the combustion chamber, and affects engine temperature, carbon buildup, spark plug life, engine lubrication, and, when too far from ideal, can lead to engine failure, either because of a fouled plug that wont spark (not very bad) or a seized engine due to too much heat and not enough lube (very bad).

Re: Help me reach ~40 on my Vespa Grande

i have an 82' grande and i used all those mods listed with the polini mod country exhaust (the one you are talking about. marmitta actually means muffler in italian, so yeah, but i know which you are talking about.) but anyways, i can hit 40mph without a new variator. just press in the brass bushing in the center of it till flush and there you go. kit is unnecessary for 40mph, or even faster than that. you can squeeze a lot more out of 50cc's than most people think.

Re: Help me reach ~40 on my Vespa Grande

DCC: I agree with the that statement accept for vespa peds.

I have the 13/13, hi flow filter from treats, polini top one, a milled head, and am going to install my malossi multivar as soon as I get a belt.

Without the variator, You can expect like 34-36. Also a lot of this depends on what speed your bike was to start out with, but most of the grandes were the 30mph models so whatevs. Considering you are pretty green to small engines it seems, I would suggest just the pipe and the filter. The reason most people buy the 13/13 is because either they got one of the crappy 12:10 or 12:7 or 10:7 carbs stock. Grandes I believe have the 12:12, and considering the intake is only twelve millimeters, its kind of pointless.

A vespa intake can be bored out to 13mm and cutting the crank will help with mixture intake and exhaust duration, but thats varsity shit.

For my two cents, buy either the tecno circuit, the proma circuit, or if you have the cash, the polini top one. Then get whatever hi flow filter you can, and read about jetting ad plug chops. You will need to change the jet inside your carb, and its not hard. Also, search the performance section for "vespa variator mod" and you will find out how to get rid of the brass bushing in your variator that sucks.

Re: Help me reach ~40 on my Vespa Grande

ed check my post up at the top. I think thats everything we need..

Re: Help me reach ~40 on my Vespa Grande

Thanks friends!

Re: Help me reach ~40 on my Vespa Grande

i didn't say the upgrade variator wasn't good. i just stated that i can reach more than 40 mph with just those mods.

Re: Help me reach ~40 on my Vespa Grande

and actually the vespa intake is just 10mm. or atleast that is what i have heard.

Re: Help me reach ~40 on my Vespa Grande

oh jeeze triple post. sorry! you can't remove the brass bushing alltogether. it needs to be there so the whole variator assembly doesnt woble. you just push it in.

Re: Help me reach ~40 on my Vespa Grande

I just ground my brass bushing down, I know some people can push theres in, but not mine. You are right about the 10mm intake, sort of. The 20mph versions had the 10mm intake. I think the 25mph and 30mph versions had the 12mm intakes.

Also, Ed, get a new belt and install it. It got me a couple mph and helped my acceleration. They are like 15 bucks and chances are yours is like 30 years old, dried out, curled up and stretched out. Its one of those things that you don't really think about, but actually makes a big diff.

Also, turns out I have an extry high flow filter. If you want it I can sell it too you.

Re: Help me reach ~40 on my Vespa Grande

ok, i didn't know some couldnt be pushed in. again, i just heard that it was 10mm and am not sure about the differences in intake size on the different speeds. i have a 30mph grande so when i get a chance i can measure it.

Re: Help me reach ~40 on my Vespa Grande

OK, This is going to be a marathon because I just got home from happy hour so... my apoilogies. Firstof all, most vespa engines have a 10mm intake. The 20mph versoins have a 6mm intake and a diffrent timed crank.

The polini long or country is actually a pretty good exaust with a variator. It gets a bad rap but I have 3 variated vespas including a Grande an it works better than you would expect. Of course, it's not on any of them at the moment but ..i still think it's a good pipe and a decent value. I have a Techno ciurcuit on a bike and it's OK. I have a Polini top one and it woks well but I don't know about $170 well. I have A Calibreta Simo pipe on the other and it destroys for the same price. if you are going to spend close to 200 bucks on a pipe, get the Calibreta and aside kick stand. Get what you can afford for now. If you really get into your moped, you can always upgrade later.

I think your problem is that the valve attached to your float is worn and leaking thus it floods your cylinder. That is why it ran great at first and won't run after it sits for a period and drains the tank. A new 13/13 carb will fix this problem. Get one and if you decide to drill out your intake (it's not that hard) you already have the bigger carb. Treats has a good deal on a carb, air filter, and throttle cable package. They also have a decent bolt on 64cc kit for $100.

Free speed upgrades are clean and repack your bearings, change your rear hub oil, pump up your tires, and make sure you have no brake drag. Look on the wiki and 1977 mopeds has a free vespa manual on their site. Learn how to work on your bike. It's not hard to do.

Having said all of that, I'm going to do an order from Europe next week and I'm going to order some Proma circuit pipes for vespa. I think they will be around $110 bucks or so. I have heard great things about them but I don't have one yet. If you want one, keep an eye on the buy sell forum in about 3 weeks.

Good luck on your bike and send me an email if you need help.


Re: Help me reach ~40 on my Vespa Grande

Wow, thanks! Yall have been really informative and helpful!

Re: Help me reach ~40 on my Vespa Grande

iv'e already changed the rear hub oil, and checked for brake drag, but how do you repack bearings?

as for the manual, i have the vespa owner's manual for the grande, and the manual that went to vespa dealerships for assembly of the grande. i also have a ciao repair manual which gives a ton of great info. much more then the grande manuals i have give. just thought id share that.

Re: Help me reach ~40 on my Vespa Grande

oh an for your leaky dellorto issue, i just bought a 13.13 and it still leaks. they all seem to leak at the litle spigot thing that the fuel line connects to and a little from the floatbowl.

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