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Vespa Smallframe Polini Evo 133

Vespa Smallframe on the test stand Polini Evo 133, L&S Franz, Polini Membrane, MRP

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Vespa Smallframe with Polini cylinder over 20HP

 

Today our customer John was again with his Vespa Smallframe on our Scooter Center Test bench.

Where can I find a few more horsepower in my Vespa engine? John

More power for the Vespa

During his last visit, he asked us what changes he could still make to his engine in order to find a little more power.

After we had briefly discussed what its current setup looks like, we were actually able to give some pointers through which more top performance can be obtained.

 

Motor setup

Basically, the engine is equipped with a Polini Evo cylinder, a 54 bgm crankshaft. The 30th Mikuni TMX carburetor is attached to an MRP suction device. The very best prerequisites to become a clear Ü20 unit.

With an additional processing of the outlet and the conversion of the Polini membrane to 2 flaps, the following result comes out:

 

Polini Evo 133 Vespa Smallframe on the test stand Polini Evo 133, L&S Franz, Polini Membrane, MRP

With Kytronic even better

Due to the larger outlet area, the exhaust can work much better. The small loss at 6500rpm is unfortunately due to the missing Kytronic. In the current state (red curve), a standard PK ignition system provides a ZZP of 18 ° before TDC. their service. With the Kytronic it is certainly possible to shift the red curve back to the left at 200 rpm, in the direction of the performance that starts earlier.

But all in all a nice number - have fun with it on the street!

 

(AS)

 

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Cylinder head Polini Racing for Polini 133ccm Vespa V50, ET3, SS50, SS90

With the appearance of the new Polini Evolution cylinder, the well-known Polini gray cast iron cylinder also received an upgrade and from now on has the addition "Racing" in the designation. A really massive cylinder head with an enlarged cooling surface, CNC machined combustion chamber and a copper gasket.

Due to the greatly increased material thickness and the use of a head gasket as in the Evolution cylinders, leaks on the cylinder head - provided that it is correctly installed - are a thing of the past from now on.

Fortunately, Polini offers the new one Racing cylinder head also available as a spare part that can be adapted to any “old” Polini. The ones required for assembly longer cylinder studs To attach the stronger cylinder head, a cylinder head gasket is included in the scope of delivery. We recommend this for screwing M7 nuts from Naraku.

Due to the increased cooling capacity, Polini has given the new racing cylinder head a little more compression.

We measured the difference for you with a burette.

Compared to its predecessor with 16,8ccm combustion chamber volume, the new cylinder head comes with a combustion chamber volume of 15,9ccm and thus increases the geometric compression from 8,7: 1 to 9,1: 1.

We simulated the volume of the cylinder head gasket by measuring it with grease.

The subtly increased compression, paired with the more modern shape of the combustion chamber, help the Polini gray cast iron to achieve more torque and power without the cylinder head being subjected to thermal overload. Of course, this only applies if the motor is set correctly. Of course, the new cylinder head does not iron out incorrect carburetor and ignition settings.

To be on the safe side, you should re-determine the pinch dimension after assembly and adjust the ignition timing depending on the engine setup. With increased compression it may be necessary to select the ignition point a little later (i.e. fewer degrees before TDC).

The new Polini cylinder head is also interesting for class 5 of the ESC, as it has been approved in class 2012a since 5.

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