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On the test bench, Polini210, Polini velocity stacks, SI26

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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!

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Small Vespa exhaust test Vespa PX80 original

Vespa exhaust test

As part of our development of the 125cc cylinder for the PX80, different exhaust systems were tested on a completely original PX80 in order to have references available for comparison.
We tested the following exhaust systems:

Original Piaggio (green curve)
SITO Plus (red curve)
SIP Road (blue curve)

It is remarkable how brave the Sito Plus does against the strong Road. Up to 4500rpm, the original pot is not only at eye level but even a little bit stronger to then say goodbye to the other two in a spectacular way.
As expected, surprises cannot be expected from an exhaust change on such a tame cylinder. The absolute numbers only result in a difference of a maximum of half a horsepower.

However, it is more important to consider the performance curve here. So the engine with the Sito Plus at 7000rpm still has a remarkable 5HP on the rear wheel, the original pot only has 3,5HP.
The 7000 rpm correspond to approx. 80 km / h in fourth gear (the diagram shows measurements in third gear). So there are only 2,5 HP more on the rear wheel by changing the exhaust with the Sito Plus.
The result is that the motor can maintain this speed much better without being forced to its knees by increased driving resistance such as an incline or headwind.
The SIP Road, on the other hand, has more torque in absolute terms, but this is applied much earlier and, in direct comparison to the Sito Plus, is only noticeable in the draft or mid-speed.
Here, the final translation might have to be lengthened somewhat in order to utilize the full potential of the system.

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