Carburetor MXT RACING 21 mm Type PHBG red with 5 mm Main Jet Oil Connection Vacuum Connection

The MXT-RACING carburetor Type PHBG with a 21 mm bore is used for mixture preparation in two-stroke engines and is frequently used in conversions and tuning work. The configuration for a 5 mm main jet corresponds to the typical PHBG jetting. A service opening on the float chamber facilitates main jet replacement without having to completely disassemble the carburetor for each adjustment.

Product Features:

• Slide carburetor Type PHBG with 21 mm bore
• Designed for 5 mm main jet
• Oil connection available
• Vacuum connection available
• Starter operation via cable
• Float chamber made of metal
• Service opening on the float chamber for quick main jet replacement
• Color variant red

The equipment is designed for variable installation and clean tuning via the main jet, as the service opening can simplify jet replacement in the installed condition. Oil and vacuum connections support integration into setups with separate lubrication or vacuum-controlled fuel supply, if the vehicle is designed accordingly. The manual starter via cable is relevant for the cold start phase and must match the existing actuator on the vehicle.

Technical Details:

• Carburetor type: PHBG
• Design: Slide carburetor
• Bore: 21 mm
• Intake manifold connection width: 25 mm
• Air filter connection width: 32 mm
• Air filter connection width with adapter ring: 38 mm
• Main jet: 5 mm version
• Choke: Starter manual via cable
• Connections: Oil connection Vacuum connection Overflows
• Float chamber: Metal
• Color: red

The connection dimensions are crucial for the mechanical fit on the intake manifold and at the air filter connection, while oil and vacuum connections define the technical integration into the respective supply system. The 5 mm main jet determines the jet type used and forms the basis for tuning to engine and air filter configuration. With a suitable geometry and correctly tuned main jet, the mixture preparation can be specifically adapted to conversions.

Vehicle and Model Compatibility:

• Universal use only with a suitable connection geometry and matching intake system
• Can be used in various two-stroke vehicles, provided the 25 mm intake manifold connection and air filter connection 32 mm or 38 mm with adapter ring fit
• No standard assignment to specific models possible, as conversions and different series versions influence the fit

Installation and Application Notes:

• Before installation, the connections for gasoline, oil and vacuum on the vehicle must be checked. Starter cable and actuation play must be adjusted before commissioning. The main jet must be tuned to the respective engine and air filter configuration. After installation, idle speed, gas response and spark plug image must be checked to avoid malfunctions due to incorrect connection or unsuitable jetting.

A correct connection is functionally relevant, as vacuum and oil connections must be actively used or securely closed, depending on the setup, to avoid disturbances in the fuel system or air leaks. Main jet tuning affects mixture preparation under load and is therefore crucial for engine performance and thermal stress. Checking gas response and spark plug image supports the practical assessment of whether the jetting matches the configuration.

Note for checking before purchase:

• Before purchasing, the intake manifold connection 25 mm, air filter connection 32 mm or 38 mm with adapter ring, starter actuation via cable, as well as oil and vacuum connection on the vehicle must be compared. The carburetor is not vehicle-specific, therefore adjustments may be necessary depending on the setup.

Brief info: Carburetor - Installation, Adjustment & Tuning

Installation: Mount carburetor without stress, check intake manifold and gaskets for air leaks, adjust gas cable smoothly, ensure fuel supply (gasoline, oil and vacuum).

Basic setting: Mixture screw mostly 1.5 - 2.5 revolutions open, adjust idle screw for stable idle speed, always tune engine warm.

Tuning:

• Main jet = full throttle / high load
• Needle position = part load & acceleration
• Pilot jet = idle speed & start-up (usually does not need to be changed)

Check: Check spark plug image

• white = too lean
• black = too rich
• brown = optimal

Important: A new carburetor tuning is absolutely necessary after changes to air filter, exhaust or cylinder.

About the Manufacturer MXT

MXT is the powerful in-house brand of Heavy Tuned and stands for high-quality replacement and tuning parts for motorcycles, scooters and mopeds.

As a reliable alternative to OEM parts, MXT offers a wide range of cylinder kits, carburetors and crankshafts to variomatic components, fairing parts and batteries. The products convince with solid workmanship, perfect quality and a strong price-performance ratio.

Ideal for drivers looking for durable spare parts and tuning parts for many vehicle models.