MALOSSI CYLINDER HEAD Ø 63 IN CAST IRON FOR VESPA COSA - PX 125-150 CC 3117676

CAST IRON THERMAL GROUP Ø 63

CYLINDER

The cylinder has a bore increased to 63 mm with a displacement of 178cc and a completely revised internal fluid dynamics. The new porting allows for correct coupling with both connected crankcases and completely original crankcases, and includes a special profiling designed to optimize flow and obtain significant increases in performance, even without carrying out additional work on the vehicle.

TRANSFERS

The intake ports have a profile designed to correctly orient the incoming flow and obtain high turbulence, thus ensuring improved combustion efficiency and optimal scavenging. These improvements allow for increased combustion efficiency, reduced fresh charge losses at the exhaust and maintaining the temperature in the chamber within permitted levels, even on the piston crown.

The rear transfer ports have been the subject of an in-depth study which led to the definition of an innovative double-inclination profile.(1-2)Which, by exploiting the well-known Coandà effect, allow for a greater flow rate compared to traditional rear transfer ports, while differentiating the orientation of the jet from the single inlet port of the combustion chamber: in this way it was possible to reduce the short circuits of fresh charge at the exhaust and simultaneously increase the quantity of fresh mixture introduced.

The exhaust has also been thoroughly revised and features new, wider phasing and a redesigned profile to ensure the correct flow of gas outgoing and directed towards the muffler.

PISTON Ø 63

The Ø 63 double-band piston calculated and optimized thanks to hours of testing in the test room. The piston has a profile designed to cope with the high temperatures developed in the chamber during operation, especially in the most demanding conditions. Allowing the piston to assume the correct cylindrical shape, once the operating temperature has been reached, allows for a more uniform sliding surface to be obtained for the cast iron cylinder. Thanks to this new profile, it was possible to reduce the coupling play between the cylinder and the piston to ensure greater guidance in the alternating motion in the barrel and reduce rotations around the piston pin axis, thus decreasing the risk of seizure, a very dangerous and recurring phenomenon in high-performance cast iron cylinders. Even the metallic clinking, audible at idle and typical of this category of vehicles, has been significantly reduced. The double elastic band guarantees the correct sliding of the piston and, at the same time, a constant seal over time to the pressures developed in the chamber.

HEAD

The head has been deeply revised starting from the cooling fins, now curved and more sinuous, able to expose a greater quantity of surface to the air and maximize cooling. The head finning has also been inserted in the gap between the head and the cylinder to generate a significant air flow capable of further mitigating the operating temperature. The result is pleasing to the eye for its unique and original shape due to the accurate positioning of the fins, whose design is interrupted only when indispensable, with respect to the fixing holes of the stud bolts. The structure of the head itself has been deeply revised by increasing the mass to obtain record-breaking rigidity, combining lightness and the maximum possible length of the cooling fins and exploiting all the space made available by the conveyor. The inside of the head is hemispherical and machined with numerically controlled machines. The positioning of the spark plug is significantly inclined, while remaining central. The kit includes two centering bushings to ensure perfect coupling between the head and the cylinder, separated only by an O-ring. This solution, imported directly from the world of competition, guarantees maximum sealing and the greatest possible heat exchange, eliminating any type of gasket and therefore removing any barrier between the head and the cylinder.

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