Vespa Tuning/Gearing Q's

Hey guys, I've been tuning my Ciao for a little bit now trying to get it dialed in and it's getting pretty close and running really well! However, I'm having an issue getting it to go faster than about 32mph on the flats. Here's the setup:

-DR43 lightly case matched, Malossi head w/gasket, ported 13mm intake, opened contact patch (not too big), Mazzu anticipato crank, Gianelli Fire.

-13:13 SHA, 70 or 72 jet (can't remember exactly which atm)

-Points set at .016

-Polini Variator, 6g weights

-Malossi belt

-Stock Euro clutch with Malossi black springs (2000rpm clutch engagement), aftermarket steel bellhousing

-12.5 : 1 gears in the transmission on Si cross mags

The engine runs good with a steady idle, has good pull throughout the powerband, gets up to speed quickly and can pull pretty decent hills at ok speeds. I feel the variator is tuned pretty spot on as the pipe comes on and pulls right in the beginning of variation and pulls it to full variation plus a few more rpm after that. After that though it's like it hits a wall even though the engine is pretty up there in RPM's. I've messed with the jetting and different weights up and down the range with little difference in top speed (unless of course I tune it too far out in which top speed suffers).

I'm wondering if maybe the transmission gears are the limiting factor here? Or maybe the pipe just can't hang? What are other people with a DR and variators + super low gears pulling for top speed? I've searched the forums and have found other people experiencing the same issues but never a resolution, I really wonder what's causing the issue.

Any Vespa gurus have some sage advice? (edited)

Re: Vespa Tuning/Gearing Q's

What contra spring are you using? Are you running 90mm clutch cheeks or 100mm clutch cheeks? Have you used a marker on the variator cheeks to ensure you are getting full variation? My grande has a similar setup and it tops out at 43mph on 12.25:1 gearing.

Re: Vespa Tuning/Gearing Q's

Stock contra spring, 100mm pulleys on a Euro clutch. I haven't marked the variator cheeks but I can see it variating as far as it will go, if I set it up with much heavier weights it'll start to variate right as the clutches grab and won't let it pull high RPM. Right now it's variating through and still pulling a little more RPM after that.

Re: Vespa Tuning/Gearing Q's

I had issues with my euro clutch not allowing the belt to variate all the way. Here’s a thread I made about it.,4105776

What I would do is pull the clutch apart and reassemble without the contra spring and pull the belt by hand between the cheeks to see how far down it will go.

Re: Vespa Tuning/Gearing Q's

something holding you back from getting to low 40's, don't think its the gearing,

Re: Vespa Tuning/Gearing Q's

I double checked the rear clutch, it doesn't look like the clutch shoes or anything else is coming in contact with the pulley. I marked the variator and the belt only rides 3/4 of the way up but when I take the belt off and close the variator I can see that where the belt is riding at top RPM is where the variator cheeks are completely closed.

I was just riding it around to see how the variator/clutches looked at certain RPMs and the rear variator somehow got stuck into the "open" position and I'm unable to close it, don't know how that could happen considering the contra is pushing on that inner cheek. I guess I'll pull the clutch, swap out contras and make sure everything is opening as far as it should but everything looked like it was moving how it was supposed to before the clutch just did this bs. These things are more of a headache than French bikes

Re: Vespa Tuning/Gearing Q's

Jeremy Edwards /

I have a ciao with polini 63 kit including head, proma circuit exhaust, modified casings and crank, malossi variator and belt, 13 carb and I find that I can't go above a 60 jet in the carb, mine runs best with a 58 and I can get 38-40mph but it is screaming at that and you certainly couldn't hold it at those speeds for long without doing damage but I do find it's got good acceleration and plenty of power for hills and will cruise fairly comfortably at 33 though, I actually expected an easy 45 with that set up but there is no way it would ever get to that with standard gearing. I think a 70+ jet is huge for that set up and think you could possibly have an air leak somewhere, as I said mine runs best on a 58 with a 70+ it wouldn't even idle without having the screw nearly all the way in, the instructions for my kit states that it works best with jets between 52 and 56 and I find that a 58 just gives it a little more power without sacrificing top speed which to me that indicates my engine is working as it should and the fact you are on such a big jet further confirms to me you have a leak somewhere, most likely at the base of the barrel but other possible areas to check are the joint in the engine casings and the oil seal behind the points, I also had the same issue with the variator only going 3/4 of the way and I modified it so it now runs to the top but in all honesty I didn't think it made a noticable difference so I wouldn't blame that for now. I will be interested to know if you have managed to get any further forward with yours?

Re: Vespa Tuning/Gearing Q's

yes to the air leak at the base gasket, on one of the transfer edges it thin like 1mm, you can find it by spraying carb cleaner on it and it'll die.

I cleaned and added a chunk of jb weld to seal.

Re: Vespa Tuning/Gearing Q's

Have you tried lighter than 6g? You may still be over variating not letting it rev out

Re: Vespa Tuning/Gearing Q's

I would check that nothing is binding too, sometimes the front vari can rub the frame, gearbox tight, old gear oil, brakes. I dunno, that setup should be jamming.

Re: Vespa Tuning/Gearing Q's

Jeremy Edwards /

Yes I had to do the same on engine casings, as the area for gasket was so thin it would prob never have sealed. I think the over variation is possible too if still running the standard rear spring, I know with the malossi variator I got a yellow spring which is a fair bit stiffer than standard one and it came with 6g weights for that, although I do feel they were just slightly light prob 6.5g would be better

Re: Vespa Tuning/Gearing Q's

Dirty30 Dillon /

If you didn't use a decent fiber gasket for the base, there's a high likelihood you have a leak. Also, despite the indexing collar (which often gets lost on rebuild) the vespa cases can end up very slightly twisted, leaving high spot-voids at the 12/6 position. When you rebuild it's always a good idea to check that the base surface is as close to perfect at the seams, before you install your engine peripherals. It's easily adjusted by loosening the case bolts and some taps with a rubber mallet.

Re: Vespa Tuning/Gearing Q's

Update: finally took the variator apart, found out the brass bushing the pulley rides on seized, causing it to stay open. I pulled the clutch apart, replaced the pulleys with Treats' aftermarket set with the vented bushing. Replaced the clutch pads with a NOS Piaggio set and replaced the stock contra spring with a yellow Malossi piece. I was tired of dicking with old parts and basically just replaced everything.

Now when I try to put it on the bike it rubs straight on the frame, you can see in the pic where the back of the pulley is wearing a groove into the frame, and this is just from hand spinning the clutch. Apparently these pulleys are slightly different dimensions, am I unable it run these pulleys? Is there supposed to be a spacer or something in between the gearbox and back of the clutch unit to keep it from rubbing?

I've never genuinely hated a moped more than this one lol.


Re: Vespa Tuning/Gearing Q's

Bump, anyone else have any issues with these pulleys? I can't get them to fit no matter what. I think I may just swap frames, maybe something is weird because this is a Euro frame.

Re: Vespa Tuning/Gearing Q's

todd amundson /

I shimmed out some 100mm cheeks on a ciao. I made a 13x10x1mm hardened washer. Goes on the rear shaft before the variator/clutch assembly goes on. 1mm spacing was just right.

If you can fit the shim down inside the variator it’s easier to install than putting it on the shaft first.

Re: Vespa Tuning/Gearing Q's

I ran those pulleys without any issue with rubbing on a subframe bike. Mine did come stock with 100mm pulleys stock, but I didn't add any sort of spacers just reassembled same way it came apart. (edited)

Re: Vespa Tuning/Gearing Q's

> todd amundson Wrote:

> -------------------------------------------------------

> I shimmed out some 100mm cheeks on a ciao. I made a 13x10x1mm hardened

> washer. Goes on the rear shaft before the variator/clutch assembly goes

> on. 1mm spacing was just right.


> If you can fit the shim down inside the variator it’s easier to install

> than putting it on the shaft first.

I'm having a hard time visualizing what you're talking about, do you have a pic? Are you saying that you put a spacer on the smaller diameter of the output shaft so the clutch assembly bottoms out 1mm further out from the frame?

Re: Vespa Tuning/Gearing Q's

Jason ( ͡° ͜ʖ ͡°) /

I'm late to this party but I don't think I saw this mentioned. Do you have pics of your bored out 13mm inlet? I'm betting this is what's holding you back. Boring out the inlet can be done in like a million different ways, and sometimes it's done extremely conservatively. Do you have any photos of it?

Ideally it should look close to the attached image, although this is pretty extreme. After the dremel or drill press, you need to use a round file to really open up the inlet and make the whole intake a round funnel shape. Pic from ciao nl attached. I've seen multiple scenarios where I got an engine that someone said was "bored to 13mm" and the intake patch was literally not tochhed at all. They just drove the drill bit down like 15mm and stopped. This creates a MASSIVE wall for the air and fuel to smash against (eddying) and often makes your engine worse off. You'd be better off not touching it at all. The whole entire thing needs to be opened up on the left and right. This doubles as a way to alter your intake timing pretty significantly as well. After porting my intake the intake duration is 168deg and I'm pretty sure vespas are typically like 150 or so stock? Someone correct me?

Anyways I digress. But yeah if you could provide some more details on how you did the inlet porting that would be helpful. Out of all the modifications you did I think this is the biggest wildcard as to top speed. The additional intake timing from correctly modifying the inlet is huge for high rpm ripping.


Re: Vespa Tuning/Gearing Q's

Here's a pic of it ported out. I posted it before and everyone said it looked fine. This was just a pic of how wide I ported the window before I worked the inside wall for a nice smooth flow.

Regardless it doesn't matter atm as I'm trying to figure out how to get the euro clutch properly mounted to make it run at all lol. I think it may be an issue with the frame.


Re: Vespa Tuning/Gearing Q's

Bump, still pondering this clutch setup.

Re: Vespa Tuning/Gearing Q's

Just put a spacer on the shaft before the pulley, I’m running a Polini Variator that stuck out waaaay to far and had it machined down now it’s perfect. Same thing but diffren, use a spacer.

Re: Vespa Tuning/Gearing Q's

In this picture it looks like the locking nut was rubbing on the transmission. Are you sure the fixed cheek is completely seated on the shaft of the clutch?


Re: Vespa Tuning/Gearing Q's

Matt Grantonic /

Concerning the rubbing issue, I had the same problem on my Grande and I recall missing some of the bearings on the chain side and it caused the wheel to flex on the hub. I ordered a new pack of bearings on ebay for cheap and just replaced them all Not sure of the size but I just used a caliper to measure and got it right. They are small and it took some time but fairly easy.

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