Restore peak compression and reliable sealing in Honda TRX400FW Foreman 4x4 engines built between 1995 and 2003 with a piston ring kit sized for a 0.25 oversize bore. Replacing worn piston rings that have lost tension eliminates blow-by and oil leakage, helping recover factory-like power, throttle response, and smooth operation. Designed to meet OEM specifications while delivering the durability and value of an aftermarket solution, this kit is a practical upgrade for trail rides, farm duty, and weekend work alike. The 0.25 oversize rings bring bore seating back to proper specification, restoring accurate clearance and sealing under rugged conditions.

These rings address common wear-and-tear problems that plague mid-life TRX Foreman engines—ring tension loss, glazing, and imperfect sealing that lead to compression drop and higher oil consumption. An aftermarket replacement that uses robust materials and precise tolerances helps you regain reliable performance for demanding off-road tasks and daily farm use, with a cost-effective rebuild path that minimizes downtime.

Comprehensive Vehicle Fitment

Fitment notes pulled from commonly referenced listings for the TRX400FW Foreman 4x4 platform from 1995 through 2003. These sources corroborate the era and single-cylinder nature of the engine family these rings are designed for.

Product Specifications

Notes: The standard bore for these TRX400 engines is 86.00 mm; selecting a 0.25 oversize kit targets an approximate bore of 86.25 mm to restore proper clearance and seating. OEM references and cross-reference notes are provided in the cross-reference table below.

OEM & Aftermarket Cross-Reference Information

Cross-reference notes reflect common aftermarket mappings to OEM Honda part numbers used for TRX400FW Foreman 4x4 (1995-2003).

What's Included

Each kit is designed for one cylinder and includes the essential rings to restore proper sealing on the TRX400FW engine:

• Top Compression Ring
• Second Compression Ring
• Oil Ring

Note: Related components such as pistons, circlips, or wrist pins are not included.

Why Choose This Aftermarket Replacement?

• Direct-Fit Compatibility: Precisely matched to Honda TRX400FW Foreman 4x4 engines from 1995–2003 for straightforward installation.
• OEM Cross-Reference: Includes cross-reference to OEM-equivalent numbers (13021-HM7-003 and 13021-HM7-004) for fit verification.
• Premium Materials: Durable steel alloy with chrome-plated compression rings designed to resist wear and maintain sealing over time.
• Accurate Oversize: 0.25 mm oversize restores correct bore clearance after wear, helping regain compression and control oil consumption.
• Solid Value: A rebuild-quality option that offers genuine rebuild performance without OEM-price premiums.
• Reliability in Harsh Conditions: Built to stand up to trail, farm, and weekend-warrior environments where dust, heat, and load are constant.

Installation Notes:

• Measure bore after removing old rings: Confirm standard bore is 86.00 mm; plan for a 0.25 mm oversize if you’re choosing the 86.25 mm configuration.
• Install in the correct ring order: Top compression ring, second compression ring, then oil ring per cylinder.
• Check ring end gaps and seating: Follow the service manual’s specifications for ring gap spacing in the bore; avoid gaps aligning across rings.
• Lightly lubricate rings and bore: Apply a thin coat of clean engine oil to rings and the cylinder wall before assembly.
• Ensure proper piston orientation: If using a piston-with-rings kit, verify any orientation marks on the piston crown point toward the exhaust side.
• Break-in procedure: After assembly, run a light-to-moderate load break-in to seat rings properly before returning to full power.

Why Upgrade?

Running a worn or undersized set of rings on a TRX400FW can lead to persistent compression loss, increased blow-by, higher oil consumption, and degraded throttle response. Replacing with an accurate 0.25 oversize kit restores proper bore clearance and sealing, delivering reliable compression and calmer oil control for dependable performance in tough trail and farm conditions.