Malossi 178cc Cylinder Kit for Vespa PX 150.

 

CYLINDER

 

The cylinder has a bore of 63 mm with a displacement of 178 cc and completely revised internal fluid dynamics. New port mapping allows for a high degree of coupling both with linked sumps and with completely new sumps, and includes a special profiling designed to optimize flow and obtain significant increases in performance, without the need to carry out any additional work on the vehicle.

 

TRANSFER PORTS

 

The transfer ports have a profile designed to correctly orientate the incoming flow and obtain a high degree of turbulence, thus ensuring improved combustion efficiency and optimal scavenging. These improvements make it possible to increase combustion efficiency, reduce fresh load exhaust losses and keep the temperature in the chamber within permitted levels, even on the piston crown.

 

The rear ports have been the subject of a significant degree of research that has led to the design of an innovative double inclination profile, which, by exploiting the Coandà effect, allows for a greater range compared to traditional rear ports. This reduces incomplete combustion of the fresh exhaust and simultaneously increases the amount of the injected fresh fuel/air mixture.

 

Even the exhaust port has been the subject of a major overhaul and includes newer and larger timing and a redesigned profile to ensure the correct flow of exhaust gases directed towards the exhaust pipe.

 

The piston contains a double guide strip designed and optimized over many hours 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 severe conditions. It allows the piston to take on the proper cylindrical shape, once the working temperature is reached, and allows a more uniform sliding surface over the cast iron cylinder. This new profile reduces the coupling clearance between the cylinder and piston to guarantee greater drive in the reciprocating motion in the cylinder walls and reduces rotations around the wrist pin axis, thus reducing the risk of seizing, a very dangerous phenomenon and common in high-performance, cast-iron cylinders. Even the metallic jingle, audible at low levels and common in this category of vehicles, has been significantly reduced. The double, elastic piston ring guarantees efficient sliding of the piston and provides a continuous seal over time to the pressures developed in the chamber.

 

The head has been heavily revised, starting from the cooling fins, which are now curved and more winding, exposing a greater surface area to the air and maximizing the cooling effect. The head fins have also been inserted into the cavity between the head and the cylinder to create significant air flow, capable of further improving operating temperature. The result is pleasing to the eye for its unique and original shape thanks to the precise positioning of the fins, the design of which only stops when absolutely necessary, at the holes for inserting the fixing screws. The very structure of the head has been revised, increasing the mass to obtain record rigidity, bringing together lightness with maximum possible cooling fin length, and making most use of space freed by the conveyor. The inside of the head is hemispherical and is worked with digitally controlled machines. The position of the spark plug is noticeably inclined, even though remaining in the center. The kit contains two centering bushes to guarantee perfect coupling between the head and the cylinder, only separated by an O-ring. This solution, which comes straight from the world of competition racing, guarantees maximum hold and maximum possible heat exchange, eliminating almost all kinds of seal and so removing all barriers between the head and the cylinder.

 

3117676

 

Piston Diameter 63 mm

 

Power range 14 / 22 hp.

 

Stroke 57

 

Compression ratio 1:10,5

 

Piston rings 2

 

Ports 6

 

Head Hemispheric

 

Spark plug IW 27Ref- MCK2, M314093, M3114935

 

 

Fits:

Vespa PX 125

Vespa PX 150

Genuine Stella 2T

 

Replaces

314093

3114935

3116244

3117181

3117676

 

 

04/26/2020

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