Restore engine compression and sealing with a +0.50 mm oversize piston ring kit designed for the TRX400FW Foreman models produced from 1995 through 2003. This single‑cylinder, four‑stroke kit targets worn rings that fade under high mileage, delivering a tighter seal and improved power on both trail rides and hard work days. It provides a practical rebuild option that restores factory-like performance without the cost of OEM parts.

Built to endure the rigors of trail riding and farm duty, this oversize ring kit addresses common wear such as compression loss and increased oil consumption from worn rings. The precision fit and durable materials offer reliable sealing under load, helping you maintain dependable ignition, smoother idle, and consistent throttle response when the going gets rough.

Comprehensive Vehicle Fitment

Product Specifications

OEM & Aftermarket Cross-Reference Information

What's Included

The kit includes the essential piston ring components sized for +0.50 mm TRX 400 engines.

• Compression Rings (2 pcs)
• Oil‑Control Ring (1 pc)
• Piston Ring Set (+0.50 mm Oversize) for one cylinder

Related parts not included: pistons, circlips, and gaskets.

Why Choose This Aftermarket Replacement?

• Direct‑Fit Compatibility: engineered to match the TRX400FW Foreman bore and ring lands for a reliable, drop‑in seal.
• OEM Cross‑Reference: stays aligned with Honda’s 13031‑HM7‑003 / 13031‑HM7‑004 standards while delivering aftermarket value.
• Premium Materials: high‑grade steel alloy with proven ring face coatings for wear resistance and sealing performance.
• Precise Oversize Fit: +0.50 mm oversize rings restore proper compression and reduce blow‑by on worn units.
• Performance Restoration: helps recover power, throttle response, and efficiency after engine wear.
• Cost‑Effective Choice: a practical alternative to OEM pricing without sacrificing reliability on trails or work tasks.

Installation Notes:

• Always ensure the engine is cold and disconnect the ignition before starting any top‑end work.
• Inspect the cylinder bore for scoring or excessive wear; measure bore diameter to confirm compatibility with the +0.50 mm oversize rings.
• Lubricate all rings and the piston with clean engine oil before installation to promote proper seating and sealing.
• Install rings with correct orientation and stagger end gaps (typically 180 degrees apart) to minimize fuel‑air entrainment and blow‑by.
• Use a proper piston ring compressor to seat rings evenly into the bore; avoid twisting or deforming rings during installation.
• After assembly, verify clearances and perform a careful break‑in procedure to seat the rings effectively and prevent glazing.

Why Upgrade?

Running a worn piston ring set leads to compression loss, increased oil consumption, and degraded engine performance. This oversize replacement restores sealing integrity and compression pressure, helping the engine regain reliable power and efficiency for demanding trail or farm use.