This piston ring kit is a precision top-end rebuild solution designed for a single-cylinder four-stroke engine found in mid-1990s to early-2000s utility ATVs. It covers model years 1995 through 2003 with an oversize +1.00 mm bore on an 87 mm cylinder, delivering restored compression and improved oil control. Built to withstand rugged trail and farm work, this kit helps restore peak throttle response, power, and reliable cooling during demanding use. By replacing worn piston rings, this aftermarket kit directly tackles common wear issues that degrade performance over time—loss of compression, higher oil consumption, and smoky exhaust. It offers a cost-effective, reliable option for riders and operators who demand durable top-end performance in tough environments, without the OEM-part price tag. It's a dependable choice for trail rides or field maintenance where consistent seal and oil management matter most.

Comprehensive Vehicle Fitment

Manufacturer	Models / Series	Years / Details
Honda	TRX 400FW Foreman (TRX400FW, 4x4)	1995–2003; 87 mm bore; oversize +1.00 mm

Product Specifications

Attribute	Details
OEM Reference Part Numbers	13051-HM7-003, 13051-HM7-004
Type	Piston Ring Kit
Manufacturer	Aftermarket Replacement
Application	Honda TRX400FW Foreman (1995–2003)
Bore Size	87 mm
Oversize	+1.00 mm
Ring Count / Per Cylinder	Top Compression Ring, Second Compression Ring, Oil Ring (1-cylinder engine)
Cylinder Arrangement	Single-Cylinder Top End
Packaging Quantity	1 kit

OEM & Aftermarket Cross-Reference Information

Part Number	Brand / Type	Cross-Reference Notes
13051-HM7-003	Aftermarket Replacement / OEM Reference	Direct replacement for TRX400FW 1995–2003; aligns with OEM family references
13051-HM7-004	Aftermarket Replacement / OEM Reference	Alternate OEM reference used in some listings; same 87 mm oversize lineage for TRX400FW 1995–2003

What's Included

The box includes the essential piston rings for the TRX400FW top-end rebuild.

• Piston Ring – Top Compression Ring
• Piston Ring – Second Compression Ring
• Oil Ring

Note: related gaskets, seals, or the piston itself are not included.

Why Choose This Aftermarket Replacement?

• Direct-Fit Compatibility: Precisely engineered to replace OEM 13051-HM7-003 / 13051-HM7-004 on the TRX400FW (1995–2003) without modification.
• OEM Cross-Reference: Aligns with widely used OEM references to ensure reliable aftermarket compatibility.
• Premium Materials & Construction: Built to endure heat, friction, and high RPMs of a demanding top-end rebuild.
• Performance Restoration: Restores compression and oil separation to bring back power, throttle response, and smoother operation.
• Cost-Effective Maintenance: A durable aftermarket alternative that saves money while maintaining engine integrity.
• Trail- and Farm-Ready Durability: Designed to withstand rugged, real-world conditions where reliability matters most.

Installation Notes:

• Verify bore size is 87 mm and oversize +1.00 mm matches your cylinder.
• Clean the cylinder, grooves, and surrounding area thoroughly; remove any debris before assembly.
• Check ring end gaps per service manual or OEM guidance; ensure gaps are within spec.
• Lubricate rings with clean engine oil before installation to prevent dry friction on startup.
• Install rings in the correct order and orientation: top compression ring, second compression ring, then oil ring.
• A proper break-in procedure after engine assembly is recommended to maximize seal and longevity.

Why Upgrade?

Running a worn piston ring kit allows compression to fall and oil control to degrade, leading to power loss, higher oil consumption, and smoky exhaust. This replacement restores compression and oil separation, delivering reliable power and smooth operation under demanding trail or farm conditions.