Modern Vespa

Shaun, I would not expect the Malossi head to be compatible with the Polini cylinder due to variances in the actual fitting between the two makes, and the seal fittings etc. I'm judging that by what I can see from the photo's in this thread and from memory of when I fitted a Malossi kit to a customers bike. The head and cylinder MUST be totally compatible when doing an upgrade like this. They are perfectly matched at the factory and interfering with anything is a no no.

there is another cylinder kit to consider pairing with malossi head. the Taiwanese are serious about their scooter performance. the 335cc complete kits for xmax 300 are dyno proven double hp. 16whp stock to 33whp! it uses CM cylinder kit.

kit for vespa appears well designed. the cut on piston would relieve piston to valve contact worries. just my observation. I havent used kit.

CM 77mm 293cc PIAGGIO MP3 VESPA GTS 300 Aprilia SR 300 Max Big Bore Cylinder Kit

https://www.ebay.com/itm/CM-77mm-293cc-PIAGGIO-MP3-VESPA-GTS-300-Aprilia-SR-300-Max-Big-Bore-Cylinder-Kit/264731415491?hash=item3da338d3c3:g:ipAAAOSw01dZmvbF

Good find Jerry! Just need someone to try it out now. The GTS engines are very strong so could certainly take much more hp. Although I think I would draw the line at 30hp for the sake of long term reliability. But, you can actually get that from a Malossi kit if you do it right and use the right exhaust.

Setting off for a ride on Saturday, Sunny died on me.
(Sunny is my Vespa with the Polini 294 kit.)

I haven't done the full trouble shoot yet, but a sudden failure tells me it is electrical in nature.
I noticed that the controller that came with the kit is not showing power on the LED as it used to...

This GTS is the most tricked out I have read about...

https://scooterlab.uk/30bhp-vespa-gts-gone-mental-sunday-sluk/


For me, the 22 BHP of my standard 300 is fine and if I want to go faster I take my bike instead but horses for courses heh.

Must have cost a pretty penny or two to mod to that level. Props to the tuners.

Let us know how you get on with the tuning project if you do go that way.

Cheers.

Were you able to fix your controller? I'm dying to hear how well this works. Almost ready to flip the trigger on the Malossi Kit, but the Polini is a good deal, just wondering how it compares.

Hides his face behind his hand in severe embarrassment...

Vespa guru was not available to assist yesterday morning, so I towed the scoot to a private freelance Vespa tech nearby. He and I spent an hour thinking and checking connections and bridging out the Polini controller to go back to the Vespa one and zero luck - Sunny just will NOT start.

Just then, my Vespa guru rides up, doing a final road test on a 250 GTS he is selling to a colleague of mine. Tech and I complain about how we are battling to find the fault. He turns the key, hold the front brake and hits the starter...

NOTHING but the starter cranking it over.
He holds his hand over the end of the exhaust and repeats the action.
"Plenty of fuel, so it is electrical... did you check the spark plug lead...?"

Tech and I look at each other. Guru looks into the engine bay and peers down the right hand side between the engine and the body.
"There you are... the plug lead has fallen off!"

ROOT CAUSE ANALYSIS - PROBLEM DIAGNOSIS:
Instead of the correct plug with the crimped-on nipple, I had used a plug with a screw-on nipple. Same thing, right? Same thing NO! The nipple had vibrated loose and caused the plug cap to fall off. The loose nipple was stuck the inside the plug cap.
We removed the offending plug, screwed it into the nipple caught up in the plug cap and extracted it. Then we tugged out the plug with nipple and crimped it tight. Vespa guru hauled out a brand new correct plug from his bag of tricks and we fitted it, secured the plug lead on the engine and cranked it.

VOILA! SUNNY LIVES !

So, dear Vespa famiglia and friends, if your favourite scoot cuts out while you are riding, do check the spark plug lead FIRST!

Be safe.
Ride safe.

PS: The incorrect plug will be retained for roadside emergency repairs.

SIP has new video of the polini 294 kit. gives good visuals of the design and how it works. very nice design indeed. now on my wish list.

is there now any news on your DYNO test? power? speed?

Waiting aswel

I will see if I can get a dyno test arranged this week...

I found a crack in the rubber manifold between the throttle body and the cylinder head. That was the source of the idle surging that Sunny was experiencing lately. I swapped out with a donor scoot my Vespa guru has and she is now back to her normal purr.

hard to believe this mod has been out for 10 months and there are no numbers what to expect for gains. sad.

I think it is par for the course. How long have the Malossi Lambda Emulator and Malosi ForceMaster been on the market? Not a single bit of performance information about them either.

They chuck these things out to us and let us do the beta testing for them. No guarantee, no comeback. I have several expensive performance (?) mods sitting in a box in my shed. When my ForceMaster failed, I couldn't get any response out of Malossi. They just referred me to their user forum.

WAIT FOR IT...


Here's the numbers:

(PS the dyno still runs on Windows '98 OS !)

So, in round figures, I increased the engine capacity by 7.3%, gained 2 HP (12%) and 15Kgf (15%) more torque, all at lower RPM / speeds.
Acceleration 20km/h to 110km/h is down from 14.6s to 12.8s

For interest sake, we ran a single test with the airbox disconnected.
That single change resulted in another 1HP (=18% up) and 7Kgf (=22% up) more torque from stock.
The OEM airbox is clearly limiting airflow in the higher RPM range.
I'm now looking for another airbox from an insurance write-off to do some experimenting...

NB: OEM exhaust is fitted in all the above results

After all the interest in getting the dyno figures before and after my Polini upgrade, the total lack of response to the results is demoralising.

Well...?

I appreciate your input on the kit. I didnt want to be the first to comment. the gains are great for what amounts to just 20cc increase.

Greetings:

Please accept a belated Good job and good Gains with the 294! I hadn't stumbled across your post until now, but I'm a freak for go-slightly-faster upgrades like you are.

Wonder how much effect an aftermarket exhaust might have? In my own experience, little 2-strokes absolutely come alive with the right pipe, but fall flat if it's wrong. 4-strokes don't respond quite so much to exhaust mods, but if the stock pipe is restrictive... Might have to re-flash the ECM if you modify the air box, but have NO idea who has that expertise.

I haven't investigated the Polini kit very much, but just off the top it looks like you would have to cut a bit of the material off the ring at the top of the cylinder, and cut bigger indentations into the piston. Back when everything was very expensive, you could get the Polini big bore kit for the Granturismo cheaper than the cylinder kit from Malossi. But Polini didn't have a head, so people did put them together. I haven't heard a lot about them going bad.
I think the Charmo cylinder might be the one in the Polini kit. Charmo makes cylinders for a lot of different companies. As far as I can tell, nobody in Europe stocks and sells them, which is strange. If there's anything that will make a Vespa faster, someone in Germany has it for sale on a website.

I thought Bill Dog had gone missing in action in outer London during the lockdown...
Seems he's been lurking in this rev up your engine forum.
I'll have to meet him soon in a stictly distanced way in some caff soon.
Hi Bill I'm generally around, When there's a breakin the rain. Let's have a cuppa on 2 wheels.
Gass silver machine GTS 250

Hi folks I thought my fellow Donkeiskok had gone awol during Lockdown London. He's been lurking in the revving up your engine section.
Time for a socially distanced cuppa, once the rains stopped.
Give me a bell. Cheers Gass silver machine gts 250

Double Billing!

I'm a little curious why they measure time from 20-110, rather than 0-110?

It is a CVT transmission, which has a slip factor to begin with.
With a Clutch, you can apply power + torque immediately.
Once the inertia is overcome, the motor shows a comparable curve.

That makes sense. Thanks!

IIRC: the 300's deck height is 3mm taller than the 250. Boring out the small end wouldn't work unless you could offset the bore 3mm, and I believe the wrist pin is only something like 1mm or 2mm different so that would require welding anyway.

I guess a work around would be to take 3mm off of the bottom of the cylinder, (which does something unknown to the compression ratio...), but at that point you might as well swap to a 300 crank & connecting rod or full motor.

I would rather do a total engine swap to go to the 300.
With all the intricasies and multiple minor differences,
I would rather look for an insurance write-off due to bodywork damage
and salvage the entire 300 motor and drive train.

Oh dear God, I wish I'd looked at this earlier 😅😅😅
I've been trying to stuff O ring in there for two hours

The same information is in the instructions.

Sorry old thread

The clear reason the gains are so minimal is any gearbox above a Leader 125 strangles the power.
Polini do a twin plug 250cc two stroke cylinder kit but again the supporting information is limited.
I have a Kubler GTX 300 Hexagon and the Malossified LXT.
You're looking at well over five figures invested in both scoots.
I have turbocharged motorcycles too!
It was good to read this thread.