Boyesen 639 Dual-Stage Reeds for 1989–1993 Kawasaki KX125

Upgrade the intake performance of your 1989–1993 Kawasaki KX125 with Boyesen 639 dual-stage motorcycle reeds. Designed as a direct-fit replacement for the original reed system, these performance reeds help improve throttle response, airflow, and overall engine efficiency while maintaining dependable operation for motocross and off-road riding.

Boyesen’s dual-stage reed design uses staged flex characteristics to support faster opening and closing during engine operation. This helps provide stronger low-pressure, low-throttle response along with increased air velocity and flow area. The result is improved engine response across the usable power range with a minor component change that can deliver noticeable horsepower gains.

Feature: Dual-stage reed construction supports responsive intake performance. Feature: Faster opening and closing helps improve engine reaction and throttle response. Feature: Increased velocity and flow area promote improved airflow. Feature: Enhanced low-pressure response supports stronger low-throttle performance. Feature: Durable construction is designed for longer overall service life. Feature: Engine-safe design helps prevent engine damage if a reed breaks.

The Boyesen 639 is manufactured for fitment on 1989, 1990, 1991, 1992, and 1993 Kawasaki KX125 motorcycles. Verify the motorcycle model year and existing intake components before installation. This product is identified by Boyesen manufacturer part number 639 and vendor part number 59-7639.

Features:

• Dual-stage reeds support improved intake performance
• Faster opening and closing for quicker engine response
• Greater low-pressure response at low throttle
• Increased velocity and flow area for improved airflow
• Minor component change designed to deliver horsepower improvements
• Durable construction for longer overall service life
• Designed to help prevent engine damage if a reed breaks
• Fits 1989–1993 Kawasaki KX125 motorcycles