Malossi BIG DEPS 4 MHR aluminum thermal unit D 47 piston pin 12

The Ø 47 BIG DEPS 4 MHR thermal group is an innovative and unique product that combines the best features of the BIG DEPS thermal groups. This thermal group is intended for all Ciao, Si, Bravo, Boss, and Grillo mopeds and is considered the top of the range in the wide family of Moped tuning kits.

One of the distinctive features of this thermal group is its drilling, which involves fixing the cylinder exclusively to the MP-ONE Malossi crankcase using 4 studs. This allows for a more efficient distribution of forces during operation and has allowed technicians to create a perfectly centered exhaust with the axis along which the washing process develops, with a thinner and profiled crosspiece.

The cylinder is made with a primary alloy of bonified and stabilized high-silicon aluminum. It has an updated flange exhaust connection and intake transfers. The exhaust transfer is completely centered with a reprofiled crosspiece. The piston is single-ring and the head gasket is made of cast aluminum. It is fixed to the crankcase with 4 studs. The head is completely redesigned and has a high-precision coupling with the cylinder thanks to an external centering.

The cylinder draws its peculiar characteristics from the BIG DEPS range, using the same aluminum alloy, nickel-chrome-plated barrel, and the same ring washing strategy. The support surface in the front part of the cylinder is worked with high-precision diamond tools and has 4 holes for fixing the exhaust flange. This has led to a further and remarkable increase in performance.

The gaskets are enriched with a specific 0.5 mm cast copper gasket, which has a higher thermal transmission coefficient than aluminum. This allows for greater heat transmission from the combustion chamber to the cooling fins, keeping temperatures controlled and increasing the durability of the gasket over time.

The piston has been designed to correctly size the entire thermal group. The new version of the Ø 47 piston has a single sealing ring, which maintains the same sealing and pressure insulation standard, but with lower friction, improving performance and durability.

The exhaust manifold uses the same strategy as the other versions, with a steel connection with housing for O-rings that fits into the seat machined in the cylinder and is held in place by an aluminum flange fixed with 4 screws. This system ensures that the exhaust does not loosen or yield even under extreme conditions.

The head is equipped with unique features, such as profiled fins to channel the flow of cooling air along the hottest surfaces, additional side fins to direct heat towards the outside of the cylinder, and a centrally reinforced structure to increase overall strength. The head also has a perfectly centered spark plug in the combustion chamber and adequately sized domes integrated into the head's geometry.

The result of all these top-notch features and components is a head that can be mounted on any type of moped, with unique technical and performance characteristics.

SPECIFICATIONS

• Usage: Sport / Racing
• Power range: 12 / 14 hp
• Tuning level: Medium
• Recommended carburetor: Phbg 19 / Phbg 21
• Stroke: 43
• Compression ratio: 1:13.95
• Number of ports: 1
• Number of transfers: 6
• Cylinder head: Truncated cone
• Spark plug: Central iw f 27

COMPATIBILITY NOTES

Product compatible only with Malossi MP-ONE engine crankcases, article numbers 5717514 and 5717892