Polini 221 long stroke

Polini 210 goes Polini 221 long stroke! - Scooter Center - Version -
We wanted him from Polini and reported about it in 2011. Now the Polini 221 long stroke is finally here! From Monday, July 29, 2013 at Scooter Center Scootershop available

Polini 221 long stroke

Cylinder -POLINI 221 long stroke aluminum, 60mm stroke- Vespa PX200, Rally200

The “old” Polini 207 gray cast iron cylinder is a feared opponent thanks to its enormous torque, but due to the material used, it is not considered to be thermally very durable.

Thanks to the new Polini 210 Alu, this shortcoming is now a thing of the past. Due to the significantly better thermal properties of the hard-coated aluminum cylinder, the kit now runs thermally much more stable than its older cast iron counterpart. If the version for the standard hub of 57mm has already become a real bestseller, Polini is finally laying it at our request a version for the use of a long stroke shaft with 60mm stroke according to! This results in a whopping 221ccm, more than enough to get around quickly with a vehicle that usually weighs less than 100kg.

Overcurrent channels
The channel design of the cylinder was also adopted here from the well-known cast iron cylinder, but the control angles have been slightly changed / extended.

If the cylinder with 210ccm is already good for almost 15 HP and 20 Nm of torque on the rear wheel, the long-stroke variant adds several coals. The lower area, which is already very strong, is reinforced again, and the power peak and the band are expanded upwards.
Of course, the cylinder reacts with even more power to further expansion stages.

Depending on the purpose, ours is recommended here

And finally ...

The Polini is the tractor among the conversion cylinders. Its full torque and the good pulling power predestine this cylinder for the long tour as well as for the next traffic light duel! Now even stronger with an extra 10ccm!

Short facts:

  • Bore: 68,5mm
  • Stroke: 60mm
  • Connecting rod length: 110mm (series)
  • Displacement: 221ccm
  • Cylinder head: Included in delivery
  • Piston: cast iron, 2 piston rings
  • Special: crankshaft with 60mm stroke required


Please always assemble piston rings carefully. Piston rings made of cast material are only elastic to a limited extent and break relatively quickly.
Some pistons have trapezoidally profiled piston rings (so-called keystone rings), these only fit in one installation position. If the ring does not move freely, please loosen it carefully and turn it back into place 'upside down'.

POLINI 221 long stroke cylinder aluminum, 60mm stroke- Vespa PX200, Rally200
Cylinder Polini 221 Alu Vespa PX200

Polini's plan to bring the well-known 210cc aluminum cylinder for the PX onto the market in a long-stroke version (we reported), is finally taking on concrete forms.

Cylinder Polini 221 Alu Vespa PX200The new cylinder, which is presumably the well-known 210ccm cylinder (but with a longer raceway) in terms of layout, is delivered with a special cylinder head suitable for the stroke of 60mm. Further details such as control angle, compression and a performance specification are unfortunately not yet known, but we will send them as soon as available.

The The cylinder head is also available separately, since, according to Polini, it also fits the kits made of aluminum and gray cast iron with normal stroke. One will see how this is solved and what the interesting side of the head looks like.

We have published here what the 'normal' version of the Polini with series stroke (57mm) can do:

Polini 210 Alu Plug & Play

Polini 210 with processing

A special, self-made long-stroke version has already been tested here:

Polini 230cc

We expect one from the new version even broader performance curve than with the 210ccm variant, as the control angle inevitably increases through the use of a 60mm long-stroke shaft. Hopefully Polini will counteract the disadvantage of an excessively high overcurrent angle by adapting it by extending the cylinder's path. This would certainly result in an engine concept that many would like for everyday use: A lot of pressure from the low rev range, a strong middle and sufficient revving power for the motorway. The whole thing without the thermal balancing act of the old cast iron cylinders.

Polini also offers a crankshaft with a 60mm stroke to match your cylinder:

Crankshaft Polini PX200 60mm stroke for aluminum cylinder 221ccmPolini speaks of a very well balanced shaft which, thanks to tungsten inserts, should run with very little vibration even at high speeds. A modified intake time should also release more power. Here, too, we will submit all further information as soon as we receive it or have checked it ourselves.

The cylinder can of course also be operated with any other PX200 crankshaft with a 60mm stroke. A high quality and The significantly more cost-effective alternative is here bgm PRO Long stroke shaft which already proven in countless very powerful engines hat:

Crankshaft PX200 Lagnhub 60mm BGM pro

With currently €179,99 it is significantly cheaper despite the highest quality material (connecting rod + bearing!) and offers a sensibly extended inlet control angle perfect power package without the disadvantage of many other waves of spitting back into the gasr.

And finally ... Here, too, Polini is making clear its pioneering role in terms of product innovations for switch scooters. While competitor Malossi is currently limited to giving a new coat of paint to tried-and-tested but aging products simply by assigning new item numbers, Polini shows what you can do with tried-and-tested parts but a little more courage and innovative spirit.

In terms of price, the cylinder will certainly be slightly above the 210cc cylinder move because the long stroke kit is delivered with a cylinder head.

Cylinder and shaft together offer a high-capacity touring package that with a little attention to detail will certainly scratch the 20PS brand without having gear connection problems.
What more do you need?

Certainly one of the nicest innovations for PX200 drivers since the invention of the BGM Superstrong Cosa clutch...

Today a very nice Rally 200 was presented on our test bench.

The project to get an everyday tractor engine was well met here.

A serves as the basis PX200 motor, the rotary valve in the housing has been subtly expanded for more inlet angles before TDC. An original Piaggio comes as the crankshaft PX200 shaft used that was not processed.

The new 210 Polini will have a SI26 carburetor with Polini velocity stacks ventilated.

By the Polini velocity stacks the available torque increases very clearly in the lower speed range. For a comparable engine with Malossi cylinder Without the Polini funnel, almost 4Nm are “missing” in the same speed range!

On the outlet side, the Alu-Polini is fed by a SIP Road Exhaust supports.

From idle speed, there is a lot of torque and power.

18PS at 6000rpm and 23Nm from 4500rpm speak a clear language.

With a long Primary translation the torque, which is practically in abundance, can be stretched and high speeds can be achieved at relatively low speeds.

Very nice device!

As already announced, Polini brings the 210cc cylinder in a version for use with a crankshaft with 60mm stroke (standard 57mm). The already available cylinder for 57mm stroke can only be driven to a limited extent with a crankshaft with 60mm stroke because the piston has an upper so-called L-ring.
This type of ring includes or forms the upper piston closure, so it controls the channels and not the piston upper edge as usual. If you now use a crankshaft with a 60mm stroke, the 3mm extra stroke must of course go somewhere ...

Since the piston moves 1,5mm more up and 1,5mm more down, the cylinder must theoretically be lengthened by this 1,5mm. For practical reasons, for the sake of simplicity, a suitably strong base or head gasket is simply used.
The problem with the two-stroke engine is that it also has an enormous influence on the exhaust and overcurrent control angles, which are important for the performance characteristics. To make matters worse, in the stupidest case you do not change both to the same extent, but usually take advantage of the overcurrent angle. Both values ​​(outlet and overflow angle) should always be in a ratio for the best possible power output.

In the case of the Polini, it looks like you are forced to use a foot seal. If you were to use a head gasket, the L-ring placed very high on the edge of the piston would simply rebound out of the raceway.
If a foot seal is used, the control angle is generally raised and, as already mentioned, the values ​​are taken advantage of in favor of the overcurrent angle.

This can lead to the engine starting too late with its power output and also being stalled in the upper speed range by a pre-exhaust angle that is too small (the angle that the piston releases the exhaust in front of the overflow ducts). This means that it can turn down further, but the power curve drops very quickly after the power peak.

In order to preserve the characteristics of the Polini, it would be better to recommend the use of a head gasket to compensate for the multiple stroke. As mentioned above, this is not possible with the standard Polini piston, otherwise the piston ring would rebound.

Facts ...

If the Polini 210 comes with 57mm crankshaft used, it has a very touring-friendly 123 ° overflow angle and 171 ° outlet angle.

When using a crankshaft with a 60mm stroke and a 1,5mm thick base seal this changes to approx. 135 ° / 179 °.
In other words, the overcurrent angle increased by a full 12 ° CA, the outlet angle, however, only by 8 °.
Both the absolute increase in both values ​​and, in particular, that of the overcurrent angle lead to a later increase in power. The whole thing can be done very well by using a tame, broadband touring exhaust system like one SitePlus, SIP Road be compensated.
The exhaust then still ensures good performance in the lower engine speed range, the greatly extended control angles allow the cylinder to rev up further in the upper engine speed range.

230cc ???
One of our customers (Thomas aka schoeni230) has exhausted the whole thing even further and a Polini 210cc aluminum cylinder with a special one 62,5mm long stroke crankshaft combined by Scooter & Service.
In order to avoid the problem of piston ring rebound mentioned above, the Polini was created here Piston against a counterpart of Grand Sport exchanged. This piston has only one piston ring and this is conventionally shaped and sits much deeper than the original L-ring in the Polini piston.

This made it possible to let the piston run out of the cylinder by the measure,
as the piston ring just gave:








As a result, the cylinder did not have to be lined very strongly at the cylinder base (approx. 0,4 mm) so that the control angle did not get too much out of balance despite a multiple stroke of a full 5,5 mm.
So the cylinder ran at ~ 133 ° / 179 ° and a special cylinder head that accommodates the piston in the head.
Due to the multiple stroke, the piston clearly undercuts the overflow channels at bottom dead center:
In connection with a modified Sito Plus exhaust (similar to the PEP3 exhaust), the engine impresses with its enormous torque in the lower rev range, an insane range and, measured by the exhaust type used, a very good top performance.

The carburetor was a 35mm Keihin PWK on a scooter & service Diaphragm intake manifold (myth V-Force membrane) used. One came as an ignition Vespatronic for use.

The cylinder has hardly been redesigned, only the outlet has been changed minimally in width and height.

And finally ...
Despite the very long steering angle, it is an enormously mobile and broadband motor that is sure to be the best for a touring rider. Full torque from the lower speed range and still still 20PS at well over 9000rpm.

Certainly not something that can be recreated, furthermore it is often problematic to let the piston extend that far out of the cylinder. Not only because of the then mandatory head centering to ensure that the piston does not hit the head, but also because of the increased thermal load on the zone above the piston ring.

The new Polini 210 for 60mm stroke will make the whole thing feasible for 'normal' screwdrivers, especially with a much cheaper 60mm stroke shaft. With it, many will certainly be able to build their 'dream' touring engine which combines a full torque with a wide speed range and a very good peak performance!

For those who find it takes too long for the 60mm Polini with 221cc to hit the market, this article encourages you to try out unusual combinations. Ie a Polini 210 for 57mm stroke with a 1,5mm base seal and 60mm crankshaft can also be expanded into a very nice touring concept.

In the sense of a well-known one (Harry B. from E.): try it, it works!