Here we present you the two new Pinasco Zuera cylinders for Vespa V50, PK, Primavera, etc. ! In addition to some novelties in the largeframe area, such as:
Diaphragm direct intake and case-suctioned cylinders
The variant with diaphragm direct intake has been given the nickname SRV 135, while the case-suctioned cylinder has been named Zuera SS 135. Today we take a closer look at the Pinasco SS135.
The completely machined underside of the rather solid, cast cylinder head is the first thing that catches the eye. The combustion chamber with the central position of the spark plug is offset by approx. 1 mm. The cylinder head is centered on the cylinder via the outer contour of the sealing surface. A cylinder head gasket is not provided. The 8-bolt cylinder head and the generously dimensioned sealing surface should ensure a permanently reliable seal even without additional sealing elements. Pinasco recommends a tightening torque of 12 Nm for both the cylinder stud bolts and the additional M8x25 bolts on the cylinder head.
Due to the central position of the spark plug, the original opening in the cooling cover must be closed. Pinasco has paid attention to this small detail and supplies a suitable sealing plug. Here you need a spark plug with a long thread. In the case of an NGK spark plug, we would recommend a B9ES or, if you want to use your Zuera 135SS ambitiously on the racetrack, a B10EG.
Piston
The 169 g lightweight cast iron piston is fitted by Pinasco with a 1 mm rectangular piston ring and 1 mm G-shaped fuses. The suggestion of the gas flow guide in the form of the small, beveled surfaces below the piston pin is very cute. This "trick" was often used on pistons with a long skirt before it became fashionable to give the piston an open side contour. Like many modern cylinders, the piston of the Zuera 135SS also has an additional anti-friction coating. Pinasco does not experiment with the piston pin. The pin is deliberately designed to reduce weight thanks to its thin wall thickness.
Cylinder
At first glance, the design of the overflow channels in the cylinder bears a striking resemblance to the Polini Evolution. On closer inspection, however, you will discover the differences in the design. The angles of the inlet surfaces are clearly different. Due to the exhaust and overflow port height and an assumed piston clearance of 0 mm, this results in a very sporty control angle of 125°/185°. In contrast to other cylinders, the openings of the overflow channels in the cylinder base are already open. The cylinder base has a diameter of 61.3 mm, so it is not necessary to enlarge the cylinder base bore in the engine housing.
However, as with almost all performance-oriented cylinders, the open overflow channels in the cylinder base also require the fan channel on the stator housing to be adapted.
The one-piece exhaust with a width of around 66% is already manufactured with durability in mind. However, we would assume that the Zuera 135SS is slightly above the Polini Evolution I in terms of performance due to the significantly sportier exhaust geometry. Due to the angle of the overflow ducts facing the outlet, the Zuera 135SS also supports exhaust systems that like to reach higher engine speeds. The Pinasco-recommended squeeze edge of 1.0 - 1.1 mm can be adjusted using the 3 0.1 mm cylinder base gaskets supplied. When it comes to the cylinder head gasket, Pinasco is discreetly reserved, also with regard to the seal and the connection to the exhaust. An exhaust gasket suitable for the Zuera SS135 is not included in the scope of delivery, nor are the required exhaust studs. The most suitable stud bolts for the exhaust are Material from Piaggio .
The combination of M8 exhaust studs and the distance between them limits the choice of possible exhaust gaskets. Unfortunately, Pinasco does not supply a suitable gasket. The PK125 exhaust gasket from Piaggio fits on the flange. However, the outlet of the SS135 has a dimension of 31mm x 27mm. This means that the PK125 exhaust gasket does not really fit here due to the smaller inner diameter. Alternatively, you can also use the BGM exhaust gasket can also be used. With this variant, however, you have to enlarge the hole in the gasket by a few millimetres.
Exhaust studs M8(not included, we recommend Piaggio)
Pierced exhaust flange 52mm (as exhaust gasket we recommend BGM)
Cylinder base gaskets three pieces in 0,1mm
Cylinder base Ø61,3mm (suitable for Piaggio)
Cast iron piston 169gr, one piston ring 1mm
Piston pin lock type G, 1mm
Cylinder head 8-fold bolted (stud bolt + 4pcs. M8x25mm)
Spark plug 14mm, long thread, recommendation B9ES, B10ES
Position of spark plug, central
Ignition timing 17° (recommended by Pinasco)
Control angle 125°/185° with a squeeze dimension of 1.0mm and 51mm stroke
Conclusion on the new Pinasco Vespa cylinder for Smallframe
The bottom line is that Pinasco has created a sporty cylinder that offers good performance with little effort. Whether with SHB19, Polini CP carburetors and Piaggio or Polini Banana or with a Keihin 28 and a Franz - the Pinasco SS135 can be coaxed into performance ranges from moderate to sporty with the right carburetor and exhaust environment.
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Both cylinders were also used at the very popular 24h race in Zuera / Spain Spain. This is why both cylinders bear the name Zuera.
Due to the central position of the spark plug, the original opening in the cooling cover must be closed. Pinasco has paid attention to this small detail and supplies a suitable sealing plug. Here you need a spark plug with a long thread. In the case of an NGK spark plug, we would recommend a B9ES or, if you want to use your Zuera 135SS ambitiously on the racetrack, a B10EG.
However, as with almost all performance-oriented cylinders, the open overflow channels in the cylinder base also require the fan channel on the stator housing to be adapted.
The one-piece exhaust with a width of around 66% is already manufactured with durability in mind. However, we would assume that the Zuera 135SS is slightly above the Polini Evolution I in terms of performance due to the significantly sportier exhaust geometry. Due to the angle of the overflow ducts facing the outlet, the Zuera 135SS also supports exhaust systems that like to reach higher engine speeds. The Pinasco-recommended squeeze edge of 1.0 - 1.1 mm can be adjusted using the 3 0.1 mm cylinder base gaskets supplied. When it comes to the cylinder head gasket, Pinasco is discreetly reserved, also with regard to the seal and the connection to the exhaust. An exhaust gasket suitable for the Zuera SS135 is not included in the scope of delivery, nor are the required exhaust studs. The most suitable stud bolts for the exhaust are Material from Piaggio .
The combination of M8 exhaust studs and the distance between them limits the choice of possible exhaust gaskets. Unfortunately, Pinasco does not supply a suitable gasket. The PK125 exhaust gasket from Piaggio fits on the flange. However, the outlet of the SS135 has a dimension of 31mm x 27mm. This means that the PK125 exhaust gasket does not really fit here due to the smaller inner diameter. Alternatively, you can also use the BGM exhaust gasket can also be used. With this variant, however, you have to enlarge the hole in the gasket by a few millimetres.
