UNI Air Filter for 2003–2019 Honda CRF230F

The UNI NU-4137ST is a high-performance, dual-stage foam air filter designed to provide superior filtration and increased airflow for the Honda CRF230F. Unlike single-layer filters, UNI’s dual-stage system utilizes two distinct layers of foam: an outer coarse-pore layer to stop large dirt and mud, and a fine-pore inner layer to trap microscopic dust particles. This design ensures maximum engine protection in harsh off-road environments while maintaining consistent power delivery through improved oxygen intake.

Features:

• Dual-Stage Filtration: Two layers of specialized foam work together to provide maximum protection against silt, dust, and sand.

• Increased Airflow: High-flow foam technology allows the engine to breathe more efficiently than standard paper or dense OEM foam filters.

• Seamless Construction: Features UNI's "Ultra Seal" grease groove on the sealing surface to ensure a leak-proof fit against the airbox.

• Washable and Reusable: Designed to be cleaned and re-oiled repeatedly, providing a significantly longer service life than disposable filters.

• Chemical Resistant: Constructed with high-strength adhesives and foam that resist breakdown from gasoline and aggressive air filter cleaners.

Fitment:

• 2003–2019 – Honda CRF230F

• 2003–2017 – Honda CRF150F

Cross Reference: 

• Honda Part Number - 17213-KPS-900

Works with any foam air filter oil. We
recommend Motorex BIO Air Filter Oil and the
Motorex BIO Air Filter Cleaner

Part Number: NU-4137ST