Modern Vespa

I've searched the forum and so many comments on this but I'm overwhelmed now.

I have a 2022 GTS 300 HPE Sei Giorni and just want to increase the torque and keep my top end the way it is or even increase a little too. Looking for a imole upgrade without tweaking settings.

The options I'm aware of are -

- rollers or sliders? What's the difference? if I go this route which weight should I get?

- performance variator

- performance clutch



- - which of the above mods is best for my needs?


- - Do I need all of the above? What's the advantage of adding each of the above mods?

- - What would the difference be if I chose just one of the above mods?

- - also because it's an HPE, if I increase the torque, won't my rev limiter kick in sooner and my top end be lowered anyway?

- - any mod for the NON ABS hpe so the rev limiter doesn't come on?

I'm not trying to make a race bike nor do I want to break the bank. I just want quicker torque and keep my top speed and not let rev limiter kick in (at all really).

Thank you

firstly if changing rollers to a different weight then also change the torque spring in the rear pulley / clutch assembly.

I did try lighter rollers and with too light I got belt slip causing the variator to become black real quick. with slightly lighter rollers it reved higher during acceleration but no _measurable_ improvement. In the HPE these are reasonably well chosen in stock already (note: in pre-HPE there was more to gain, so expect many people with pre-HPE to comment about how great they were for them). won't help.

well, if you change the 3 springs in the clutch then a different point of engagement can be chosen. eg rev high before clutch engages - not fun for general use on the streets. no. you'd have to do insanely light rollers to high the rpm limiter before hitting the speed limiter. you won't be doing this. All hpe have ABS. to changing the rev limit you need to either modify the ecu or add a secondary ecu like a malossi forcemaster. Plus you're not going to be reving that high anyway/ basically forget it.

PS, In your profile, you don't have a GTSV - there is no such. You have a GTV.

Ahh thanks for the detailed response.

So will the Polini 9 performance variator make much difference for torque?

I see lots of people saying night and day positive difference from stock but I wonder if this coming from an HPE or not. If I habe an HPE will it matter much?

I meant the non traction control not ABS. You can get that ring for the traction control model and it tricks the rev limiter from not engaging. Not so on non traction control like mine. So no way to remove the limiter except what you mentioned?

Must be a typo gtsv. I am fully aware that model doesn't exist.




[⁴quote="SteelBytes"]
firstly if changing rollers to a different weight then also change the torque spring in the rear pulley / clutch assembly.

I did try lighter rollers and with too light I got belt slip causing the variator to become black real quick. with slightly lighter rollers it reved higher during acceleration but no _measurable_ improvement. In the HPE these are reasonably well chosen in stock already (note: in pre-HPE there was more to gain, so expect many people with pre-HPE to comment about how great they were for them).



won't help.

well, if you change the 3 springs in the clutch then a different point of engagement can be chosen. eg rev high before clutch engages - not fun for general use on the streets.



no. you'd have to do insanely light rollers to high the rpm limiter before hitting the speed limiter. you won't be doing this.



All hpe have ABS. to changing the rev limit you need to either modify the ecu or add a secondary ecu like a malossi forcemaster. Plus you're not going to be reving that high anyway/ basically forget it.

PS, In your profile, you don't have a GTSV - there is no such. You have a GTV.
[/quote]

Not gonna increase torque without engine mods.

Sounds like what you're asking for is an increase in acceleration? Simple no fuss bolt on mod is gonna be a variator contra spring combo from Malossi or Polini.

You can get close to what an aftermarket variator will do with the factory parts and spacers and lighter rollers/sliders but won't be simple bolt on.

Clutch springs or performance clutch will increase engagement RPM and acceleration off the line but are a pain to live with on a daily basis.

If you're really looking for more torque Malossi does a cam, looks like you have to install with their cylinder kit though.

https://www.malossistore.com/en/us/power-cam-camshaft-vespa-gts-hpe-300-ie-4t-lc-euro-5-2021-2022-md31m-5919264-vehpe30021-M-P

Yeah more acceleration

and also need the force master 3 or ecu remap.

I'm actually thinking of doing this combo

Curious, what do you lose in MPG and reliability?

So essentially, you're looking for quicker acceleration without losing top speed?

Most variators will do this, and they're a relatively cheap upgrade and fairly easy to swap as well.

They're also easy to undo if you ever wish to sell the Vespa stock.

Yep. Leaning towards getting the Polini 9 variator and calling it a day.

With the 9g or 10g rollers? The kit comes with 9 but 10 is recommended for a 300 i think. (The kit is for 200/250/300)

Yeah it's actually the 10.1g that is recommend. I 00 percent sure going to go for this!

Does anyone know if 9.2g rollers that it comes with would give more torque yet still be fine at high speeds?

I have the Polini 9 with the recommended 10.1g rollers installed and not much more torque. Just a smoother acceleration and little faster to get up to speed in general.

Also I have a cheap knock off Akropovic installed with no baffle (the db killer it came with was nothing like the real Akro db killer) so I wonder if that's the main culprit stealing my low end torque!

You use of ´torque´ is at best confusing.

Playing with the variator is like changing the gear ratios of the lower gears in a shifty.
Lighter weights = increasing engine revs per rear wheel revolution.
Yes this will make the scoot accelerate more peppy. No it will not do ANYTHING for the torque the engine produces.

A badly designed exhaust cán affect the engine output. There is a huge amount of engineering and development that goes in the total gas flow though the engine. It is all very well balanced and designed to work within the framework of legal requirements.
Faffing with the inlet/exhaust is most likely to be disappointing ánd you will need to remap. Just an open pot is and yes can very well be the culprit of less engine torque.

The above is avoided with the variator mods as it does not affect the engine output.

Ah yes I admit I may not know true definition "torque".

I just want better acceleration from a dead stop. My current setup - I give throttle from dad stop, while although more smooth now, There is a bit of a lag or spongy feeling from when I hit the throttle and it accelerates.

Going back to stock exhaust tomorrow and trying to decide go from from 10.g to the 9.2g weights.

In your opion, if these 9.2g weights are made for a 200 or 250cc Vespa, and I put them on on 300cc, will it make my highway speeds not as fast or just rev too high in the RPMS at highway speeds?

It will make the engine revs increase more relative to wheel revs. It will not rev out at fringe legal highway speed (just be less easy to live with) but will most likely lower top speed because it will rev over max power.
Would stick with the rollers meant for the engine by Polini.

Good luck.

For an increase in off-the-line acceleration AND keeping top speed you can fit Dr Pulley sliders instead of rollers. You should also fit an extra 1mm washer behind the driving pulley and in front of the bushing - this prevents the oil sump gasket from being torn out and also helps give even better acceleration from a standing start.
21x17x9.0g
Washer: part no. 434885

Is that with the Polini 9? That's what I have installed and would like to keep that.

Ah, no. With the stock variator.

You could just add that washer - it really makes quite a difference, as it allows the belt to go 5mm or even a bit more further down the variator. Being that much nearer to the crankshaft gives a big boost to first acceleration.

Hmm ok. I have them switch my variator weights Tomorrow. I make sure the previous guy put the washer on

The Polini 9 roller variator has largely fallen out of favor with the tuning community, mainly because they don't hold together as well as some of the other options when you put extra power through them. When it was designed, the motor it was meant for was a 180-200cc liquid cooled leader, and it's basically an OEM variator design with narrow roller tracks, that uses narrower rollers. While an HPE engine isn't going to wheelie when you give it gas, it does make considerably more hp than the engine they had in mind when the 9 roller was designed. I would be hesitant to flog it too much. The stock HPE variator has been reinforced to take the extra power, so if you want to get more acceleration out of the bike, and those are your only two choices, I would stick some 12s in the stock variator and go slightly heavier on the contra spring.

Stop trying a more open exhaust, the engine generally will lose some lower rpm torque because of reversion, maybe a little better at WOT, but who rides like that all the time ? Best and cheapest solution is put stock exhaust back on, change out rollers to sliders like The ones Jim said , and then go on a diet and lose 10-15lbs. Volia ! Problem solved !

If you like to do wheelies on take-off, put a couple of bricks into your top box.

... and sit further back on the seat.

I asked Johngeorge Landskron, my Vespa guru to comment.
JG currently lives in Brisbane, Australia.
He wrote to me as follows:

"I've had extensive experience with the Vespa GTS and have tried various variators. In my opinion, aftermarket options like the Malossi and Polini 9 roller variators are quite similar.

The main difference between the OEM and the aftermarket variators is that the OEM is tuned for lower noise levels, which causes it to shift into higher" gear" as quickly as possible. In contrast, the Malossi and Polini models offer more in-between "gears," enhancing overall performance.

Many manufacturers recommend decreasing roller weights by 10%, but I've found that with the GTS 300, especially the HPe, it delivers more torque at lower RPMs. For this reason, increasing roller weights by 10% or even 12% seems to align better with the design of the HPe engine.

I've had great success with both the Polini 9 roller variator using 10.2g rollers and the Malossi with 17.4g rollers. I've noticed that aftermarket roller weights tend to last longer, likely due to less pressure during operation.

My focus has been on enhancing acceleration from 40 km/h to 80 km/h while also improving the initial launch. I highly recommend these setups for anyone looking for a stronger mid-range punch. I have front wheel lift-off with both the Malossi and Polini configurations on my 2023 GTS 300 HPe at sea level."

Wow thanks for this. I had the Polini 9 with 9.2g weights installed today with stock exhaust and no front wheel lift off. in fact It still is a bit sluggish to accelerate. Maybe overall it gets to speed faster than stock. There is a guy on YouTube with GTS 300 HPE as well with Polini 9 and 9.2g rollers and no apparent additional mods and has front wheel lift off - (fast forward to 12 minutes and 5 seconds to see) it looks like I have the same exact setup as him and no front wheel loft off for me

That's why I got the Polini 9. I may have the 10.2g put back on. I'd love to speak with your friend John George in more detail to see what exactly he did for his HPE 300 front lift off. I sent you a message...

A front wheel hoppy like that is just a matter of dóing it.
Sit a bit back, jerk the throttle and if you have the confidence the handlebars too. With my bum back even my totally stock Primavera 125 hops the front done like this at 800 metres elevation

Enjoy!!!

If I'm seated in a relaxed upright position and take off hard at the lights then it does a little wheelie. If I'm hunched forward in a racey pose then it doesn't.