M6 Main Jet Nozzle for Derotto PHBN and PHVA Carburettor Tuning from 55 to 150

This M6 main jet is a critical replacement component for Derotto PHBN and PHVA series carburettors, used specifically to modify and tune engine performance by adjusting the fuel flow. The main measuring hole, available in a precise single size per unit from 55 to 150, determines the volume of fuel mixed with air. This makes it an essential part for mechanics, tuners, and enthusiasts looking to correct a lean or rich condition, adapt to aftermarket components, or restore a carburettor to its original specification. By selecting the correct jet size, you directly influence the air-fuel ratio, which is key to engine efficiency, power, and smooth operation.

Features and Construction

The jet is built around its core function: delivering a metered amount of fuel. Its construction and sizing are the primary factors determining its use and compatibility.

Material and Build

Manufactured from brass, the jet features the durability and corrosion resistance suitable for fuel system components. The main body is precision-machined to include the M6 external thread, ensuring a secure fit into the compatible carburettor float bowl or jet holder. The most critical aspect is the drilled main measuring hole, whose diameter corresponds to the jet's size number (e.g., 55, 100, 150). This hole is engineered to a specific tolerance to provide a consistent fuel flow rate for its designated size.

Size and Practical Fit

The product is offered in a comprehensive range of sizes, incrementing from 55 up to 150. This range covers many common tuning requirements for small engines typically using these carburettors. It is crucial to order the specific size needed, as each unit contains only one jet with one fixed orifice. The M6 thread is the standard fitting for the specified Derotto models, ensuring a direct replacement for the original part. Always confirm your existing jet size or consult tuning guidelines before selecting a new size.

Uses and Placement

This component has a specialised role within the fuel system, directly impacting engine performance and driveability.

Event or Professional Use

For professional mechanics, tuners, or competitive motorsport applications, these jets are used to precisely calibrate an engine's carburettion. Changing the main jet size is a fundamental step when modifying intake, exhaust, or compression, or when adjusting for altitude. A larger jet number (e.g., moving from 100 to 110) allows more fuel into the mixture, potentially correcting a lean running condition or supporting performance modifications.

Everyday Home Use

For the home mechanic restoring or maintaining a piece of equipment with a Derotto PHBN or PHVA carburettor, this jet serves as a direct replacement for a worn, clogged, or damaged original. If an engine is running poorly—surging, hesitating, or lacking power—and the carburettor is suspected, inspecting and potentially replacing the main jet can be part of the troubleshooting process. It allows for the correction of issues caused by degraded fuel or normal wear on the original jet's orifice.

Benefits and Buying Value

The value lies in its specificity and role in engine maintenance and performance tuning.

Reuse and Low Maintenance

As a solid brass component, the jet itself requires no maintenance. Its value is realised through its long-term function within the carburettor. By enabling precise fuel calibration, it helps maintain optimal engine combustion, which can contribute to consistent performance and fuel economy. It is a single, reusable component that forms part of a larger serviceable system.

Why Choose This Product

This product is chosen for its confirmed compatibility with Derotto PHBN and PHVA carburettors and its wide availability of sizes. It provides a focused solution for a specific tuning or repair task. The clear size specification allows for accurate selection, making it a practical purchase for anyone needing an exact M6 threaded main jet within the 55-150 range for these carburettor models.