More carburetor cross-section without Reed Valve conversion

With tuned smallframe engines, the original DELL'ORTO SHB 16-20 Carburettor is often no longer sufficient to supply the Engine with enough fresh gas. Converting to a Reed Valve system then often seems to be the only way, but requires massive modifications to the Crankcase. These changes cannot be easily reversed at a later date. The SPORT/RACE Intake Manifolds for Disc Valve Engines are therefore an interesting Plan B. They make it possible to replace the original carburettor with a significantly more powerful tuning carburettor with a passage of up to 36 mm.

Large selection for different Carburettor and engine variants

The range includes Intake Manifolds SPORT for Disc Valve engines over 20 mm from POLINI, MALOSSI and M.R.PARTS & STYLE. POLINI offers Intake Manifolds for the DELL'ORTO PHBL 24 with plug-in connection and 2- or 3-hole mounting as well as for the DELL'ORTO PHBH 28/30 with rubber connection. These fit Vespa V50-125/PV/ET3 chassis with original 2-hole or 3-hole PK engine. MALOSSI completes the range with Intake Manifolds for the DELL'ORTO PHBL 24/25 with rubber connection and the DELL'ORTO PHBL 24 with plug-in connection. These variants are also available for both older smallframe models with 2-hole and newer PK models with 3-hole mounting. If you want maximum performance, you also need the right cross-sections.

Conclusion: It doesn't always have to be a reed valve kit. A Disc Valve Engine can also achieve decent performance with an appropriately sized Carburettor.

PURCHASE RECOMMENDATION: SIP-TIP

• Include Connecting Rubber directly in the plan
• Order theRAM AIR Air Filter as a useful addition
• Particularly interesting for powerful Disc Valve setups without housing conversion

Feedback

"Good performance. Good with Dell'Orto 24."

-SIP user "Emmanuel"

The intake manifold is the inlet duct for the air-fuel mixture to the Engine via the reed valve.

Influence on engine performance

The overall performance of an Engine is determined by several partial performances:

• volumetric power
• thermodynamic power
• mechanical power

Volumetric power describes the ratio between the amount of mixture (expressed as volume) that enters the combustion chamber and the engine's displacement.

The main factors that influence volumetric power include frictional losses of the mixture on its way from the Air Intakes or Air Filter to the combustion chamber. The intake manifold is a key influencing factor here: the mixture must flow through the Exhaust Manifold with the lowest possible losses. Therefore, large changes in diameter and sharp angles in the flow path should be avoided.

Flow, storage effect and speed range

The intake manifold also serves as a "storage chamber" for the freshly incoming mixture. As the mixture column moves at a certain speed, it needs time to slow down when the reed valve locks. The mixture collects in the Exhaust Manifold and presses against the vanes. As a result, each Exhaust Manifold is assigned a specific speed range in which maximum power is achieved (tuned manifold).

The Exhaust Manifold also acts as a Holder for the Carburettor by connecting it to the Crankcase or Cylinder. If necessary, it can also dampen vibrations that are transmitted from the Casing to the Carburettor. This helps to reduce the unwanted emulsion of air and fuel in the Float Chamber.

Design and development at MALOSSI

This seemingly simple component therefore requires sound theoretical and practical development in order to make the most of its potential - and this is precisely where MALOSSI comes in. Thanks to many years of experience in supply systems, MALOSSI has developed a new Rubber and aluminum alloy manifold line for new generation scooters, which has been tested both on the road and on race tracks.

The rubber manifolds from MALOSSI have a multi-part structure: an aluminum insert is embedded in a special plastic material that is resistant to Oil and petrol. This creates a high level of rigidity at the point of attachment to the Crankcase while at the same time ensuring the necessary elasticity of the Exhaust Manifold.