Prox Main Jet for Keihin Carburetor Size 178

The Prox size 178 main jet is a replacement main jet for Keihin carburetors, designed for precise fuel delivery and reliable performance on off-road and street motorcycles. A must-have part for enthusiasts who want targeted tuning and consistency in the rev range.

• Type: Main jet for Keihin carburetors
• Size: 178 (main jet size)
• Material: Brass for durability and corrosion resistance
• Installation: Hexagonal body for a secure grip during installation
• Compatibility: Fits Keihin carburetors, commonly used in PWK/PE series and similar models
• MPN: JU-45.178

This main jet provides precise fuel delivery metering across different RPM ranges and loads. Using the correct jet number delivers improved low-end torque, crisp throttle response, and more consistent performance when faced with variations in air and fuel quality. The brass material ensures stable metering over time and simplifies maintenance and replacement.