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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