Malossi cast iron thermal unit D 61

The Malossi Ø 61 cast iron thermal unit for Vespa PX 80 2-stroke is a product that has been renewed after 30 years of success. Thanks to continuous improvements, the legendary Ø 61 now has a new code and has undergone further upgrades, especially regarding the main and rear transfers.

This thermal unit is the only one of its kind that uses an O-ring as a sealing gasket between the head and the cylinder, ensuring better sealing and heat dissipation. The performance has been further improved, especially in terms of low-end torque. Malossi technicians have exceeded all expectations with this evolution.

The cylinder is made of special self-lubricating, wear-resistant, and highly refined cast iron alloys. The machining is carried out on high-precision CNC machines. The heat exchange surfaces have been recalculated and increased, while the exhaust ports and transfers have been designed to achieve maximum thermodynamic efficiency.

The piston is made of a special aluminum alloy with a high silicon content and low thermal expansion. The piston is also machined on CNC machines, lightened, and reinforced. The heat exchange surfaces have been increased. The rings are made of high-strength spheroidal cast iron with a hard chrome wear-resistant coating on the contact surface, ground and lapped.

The head is made of a special die-cast aluminum alloy. The heat exchange surfaces have been recalculated and increased, while the machining is carried out on super precise CNC machines with diamond tools. The head has an anti-oxidation surface treatment and the compression seal is guaranteed by a Viton gasket. The combustion chamber is hemispherical with squish and the spark plug is located in the center.

SPECIFICATIONS

• Usage: Urban / Sport
• Power Range: 12 / 20
• Processing Level: Easy
• Recommended Carburetor: Yes 24/24 PHBH 30
• Stroke: 47.5
• Compression Ratio: 1:10.8
• Number of Segments: 2
• Number of Ports: 7
• Head: Hemispherical
• Spark Plug: Central IW 27