The humble PX125 is exactly that: mild, moderate and overlooked. In terms of sporting prowess, it’s like the fat kid with asthma when it comes to selecting players for your school football team.
When you had the option of kitting a T5 or a 200cc Vespa; why would you bother? The answer is that the T5 and 200cc PX models didn’t last forever and were deleted by Piaggio long before the base model PX. A generation of learner geared scooter riders had no choice but to ride the PX125 or LML’s Indian-built variants. In Italy, there were also a wealth of 150cc versions sold because that was the minimum capacity to access the motorway network.
Pictured above, the primary components of the Barone 230 kit for PX and LML
This kit…

• Works with standard PX or LML crankcases using normal rotary disc induction. Transfer matching is advised but not essential.
• Works with a standard style carburettor. The one I tested used a 24mm PX200 carb and a carb box with an enlarged top.
• Works with the standard exhaust. The bolt-on steel exhaust stub is in the original port position so any exhaust for the PX125/150 engine will fit. The scooter I tried had a Polini Road Box fitted which is a performance upgrade of the original Piaggio box but still very quiet.
• Works with the standard gearbox. The scooter I rode was fitted with a standard PX200 gearbox which is actually wider 3rd to 4th ratio gap than the PX125 gearbox but is stronger.
• Works with a standard clutch, just with uprated clutch springs. Yes I was surprised about that too. Barone reckons that the old 6-spring design isn’t that bad particularly if the basket is reinforced. He would advise a BGM clutch if you wanted something better.
• Works with a standard ignition. The kit makes peak power at 6,300rpm so a stock ignition will work, but the original flywheel is a bit heavy. The scooter I rode was fitted with a SIP Vape ignition or Barone recommends a Polini IDM-based ignition.

Going large?
Italian tuner, Roberto Barone has recently revisited the PX engine with the idea to produce a bolt-on kit for touring and street use. Rather than making it rev hard like many smaller capacity rival kits, he decided to keep the port timings low and go for torque by maximising the engine capacity.
The capacity of 230cc is achieved by converting from a standard 57mm stroke to a dedicated 60mm stroke crank, which will be sold with the kit. The 7-transfer port cylinder is then built with a massively oversized 70mm Meteor piston from the Casa Performance SST Lambretta kit. No packing plate adaptor is required but the crankcase mouth of the casing does need boring out to accommodate the cylinder’s short, thin spigot.
The crankshaft is a 60mm stroke BGM crank fitted with a 120mm rod from Primatist. In the future the crankshafts will come pre-built with 120mm rods
Long stroke

The capacity of 230cc is achieved by converting from standard 57mm stroke to a dedicated 60mm stroke crank, which will be sold with the kit. The 7-transfer port cylinder is then built with a massively oversized 70mm Meteor piston from the Casa Performance SST Lambretta kit. No packing plate adaptor is required but the crankcase mouth of the casing does need boring out to accommodate the cylinder’s short, thin spigot.

Boring out the crankcase mouth is still a job for a proper engineering workshop and therefore the step that takes this from being an easy home-build to something a little more complicated.
The easy option?

When it comes to tuning it’s easy to get caught up with spending large and aiming for mega horsepower. That’s great for posting dyno results if you are a social media attention whore, but what about on the road?

Not only can high end tuning cost a fortune but you can end up with an engine that is no longer practical.

Apart from the crankcase boring, Barone’s kit is just the opposite. It’s not cheap, due to the small-scale manufacture and because it includes the special “Barone by BGM” crankshaft required. Those components aside, you need little else.

The cylinder has 3 exhaust ports with low timings aimed at producing low-rpm torque. The rough port finish is due to the coarse sand used for the prototype casting process. The cylinder has more holes than a Scotsman’s vest! Triple boost ports assist the four main transfers.   

An Italian may describe Barone’s kit products as ‘artigianale’ (artisan-produced) as opposed to being a factory product.

The kit I tested was still from the ‘pre-production’ stage. Only the first 20 kits have been cast in rough sand by a famous foundry in Maranello; who work for various supercar manufacturers. The rough sand used for prototype casting is a quicker process and easier to modify in order to make specification adjustments.

Now that Roberto is happy with the layout, the next stage will be to produce another batch using a much finer sand which will make the whole kit more aesthetically pleasing but is unlikely to make much difference to the performance.

The special features of the 230 kit are the specifications that you can’t see with the naked eye. In order to maximise the stability of the casting, given the PX’s less-than-generous cylinder finning, Barone specified a very hard aluminium alloy that is rich in copper and iron. This requires a much longer heat treatment process than normal. Additionally, he asked plating firm Monardi to put a double thickness of nicasil coating on the bore to aid durability and resist the chances of heat-seizing.

The piston is a 2-ring design made by Meteor, uses Japanese piston rings and has a graphite coating to aid running-in.

8-point fixing

The CNC-machined cylinder head looks similar to a design used by Parmakit. It has an 8-point fixing with an additional four M6 screws to supplement the M7 studs. Sealing is via a large O-ring around the raised combustion chamber which self-centralises in the bore of the barrel. Roberto says that he likes this style of head because it includes a central spigot, making it easy to hold in a lathe and therefore easy to modify.

The cylinder itself has a single main exhaust port with two additional sub-ports (‘boosters’ in Italian) which are partly obstructed by having to flow around the cylinder studs.

There are four main transfer ports and a further three boost ports in the back wall making 7-transfers in total.

A combination of a boxed carburettor, Polini box exhaust and SIP ignition make for a civilised ride that’s perfectly suited to touring and rallies.
On The Road

I think this conversion is exactly the sort of thing you’d like if you want standard-style power delivery but with more than double the power output.

In every other respect, it rode like a standard motor. It was still easy to kickstart. The clutch was light enough. The carburettor in the air-box was quiet, as was the Polini box exhaust. Even the rev-range of the motor was moderate; feeling more like a Polini 207 in power delivery than something revvy like a Malossi 210.

What Barone’s 230 did, that some peakier PX conversions don’t do, was reassure you that it would always pull the next gear. It accelerated in 4th even into a strong headwind. This scooter used tall 24/63 primaries offering 70mph at only 6,000 revs.

As the photos make clear, it’s perfectly possible to get a good power wheelie out of it, but it’s not so torquey that it wants to lift the front every time you pull away. Or at least it didn’t in this well set-up chassis with shortened front forks. On my short test (this was a customer’s scooter) the only negative that I could level at the engine was that it got progressively more vibey the harder it is revved. While it felt like it would happily pull 70mph plus all day in this configuration, it certainly wouldn’t be as smooth at those speeds as a T5 with a 172 kit for instance. While I call this vibration, in Lambretta terms it wasn’t even on the Richter scale: barely a tickle. If however, you are the Princess and the P(range), then you might disagree. In short, I found it very pleasant to ride. It didn’t blow my socks off but then again, with a standard carb and rotary induction, I wasn’t expecting it to either.
Barone-supplied dyno graph (i.e. not from the dyno we normally use) for the 230 in the configuration I rode. Black is the power curve against horsepower and Green is the torque curve in Newton-metres.
The Performance Option

With modest port timings the Barone 230 was never conceived as a race kit. That’s not to say that there isn’t more performance available if you fit a bigger carb and improve the inlet side of things.

Roberto’s chosen route to do that would be to start with a dedicated reedvalve engine casing, in the form of the Malossi VR-One casings. He’d use these in conjunction with a reedvalve version of the BGM/Barone crank, a 30mm carb and a Barone expansion exhaust.

In this configuration, Roberto reckons there’s a little over 30hp on offer, but still with the wide power spread that comes from only 170-degrees exhaust timing and 118-degrees transfers. At these outputs the Malossi casing is probably a good idea or else the well-known cracking issues of the Piaggio/LML casings could possibly rear their ugly heads.

Admittedly, I’ve ridden very few of the competing second-generation kits for the PX motor – of which there are now many – so I can’t position this conversion on a ‘leader board’. Let’s forget the numbers for the moment though.

Now that Vespa or Lambretta motors exist which produce more power than you can safely use on the street, perhaps it’s time to stop using outright speed and horsepower as the prime means of comparison.

Given the age of these scooters, and the people riding them, perhaps it’s not better to compare them on ease of use, cost and simplicity of assembly. By those metrics the Barone 230 seems like a strong contender. The only proviso is that you must have an engineering shop nearby who can bore your crankcase mouth.

Machining requirements aside, I could see this kit being a great practical conversion for those looking to turn a PX or LML into an all-rounder that still satisfies the original objectives of moderate noise and fuel consumption.

If that sounds like the sort of engine you’d like, and you have the 850 Euros (approx) required to purchase the cylinder and crankshaft kit then the Barone 230 might be for you.

Words, photos and video: Sticky