Koso 28mm Throttle Body: Honda Grom & Monkey 2022+

Increased Airflow: Koso 28mm Performance Throttle Body

Maximize the volumetric efficiency of your 5-speed engine with the Koso 28mm Throttle Body. Specifically engineered for the 2022+ Honda Grom and Monkey 125, this upgrade replaces the restrictive factory unit to allow a higher volume of air into the combustion chamber. The result is a sharper throttle response, improved mid-range pull, and increased top-end power, making it an essential foundation for any performance build.

Technical Performance Features

• Optimized 28mm Bore: Provides a significant increase in airflow over the stock throttle body without sacrificing the intake velocity needed for low-end torque.
• Precision Machined Internal: Features a smoothed internal bore and a high-tolerance butterfly valve to eliminate turbulence and ensure linear throttle delivery.
• OEM Sensor Compatibility: Designed to accept your factory MAP, IAT, and TPS sensors for a clean, integrated installation that maintains ECU communication.
• High-Flow Intake Path: When paired with the Koso Intake Manifold, this setup creates a streamlined "straight-shot" air path into the cylinder head.

Comprehensive Fitment Guide

This throttle body (SKU: 128-51) is designed exclusively for the 5-speed (long-stroke) Honda 125cc engine found in:

Specifications

• Bore Diameter: 28mm
• Material: Die-Cast Aluminum Alloy
• Manufacturer MPN: DY640000
• Required Modification: ECU Reset or Fuel Controller highly recommended

Pro-Tuning Note: To achieve the full performance benefits, this throttle body should be used in conjunction with the Koso 23-29mm Intake Manifold DP640000. After installation, a "TP Sensor Reset" is required to ensure the ECU recognizes the new butterfly position at idle.

Part Number: 128-51
Manufacturer: Koso Taiwan

This product is not intended for use on public roads or land.