If you're tackling a top-end rebuild on your Honda TRX 300, this aftermarket piston ring kit in OS 0.25 oversize is the precise upgrade you need to breathe new life into your ATV's engine. Designed specifically for Honda TRX 300 FourTrax, TRX300FW, and TRX300EX models from 1988 through 2000, this kit restores critical compression and sealing to eliminate power loss during tough off-road rides or farm duties. By swapping out worn rings, you'll experience smoother acceleration, reduced oil consumption, and reliable performance that keeps you going mile after mile on the trails. It directly addresses common issues like blow-by, poor fuel efficiency, and excessive smoke from a tired engine, ensuring your ride runs as strong as the day it left the factory. What makes this kit a smart, reliable choice is its engineered precision and durable construction, offering trail-proven performance at a fraction of the cost you'd expect, without compromising on the fit and function that hardworking owners demand.

Comprehensive Vehicle Fitment

Product Specifications

OEM & Aftermarket Cross-Reference Information

What's Included

Based on standard piston ring kits for the TRX300 engine, this kit includes:

• Top Ring – Chrome-faced for enhanced durability and wear resistance

• Second Ring – Cast iron for reliable heat management and sealing

• Oil Ring Set – 2 oil control rings and 1 oil ring spacer for complete oil control 

*Note: This is a piston ring kit only. It does not include the piston, wrist pin, circlips, or gaskets. For a complete top-end rebuild, pistons and additional components are available separately from Honda (13102-HC4-305 for 0.25 oversize piston)  and aftermarket manufacturers like ProX .*

Why Choose This Aftermarket Piston Ring Kit?

• Extensive Vehicle Coverage: Precision-engineered for Honda TRX300 FourTrax 2x4 (1988-2000), TRX300FW 4x4 (1988-2000), and TRX300EX Sportrax (1993-2000) models, with fitment confirmed by OEM parts diagrams  and aftermarket suppliers .

• OEM Cross-Reference: Cross-references genuine Honda part number 13021-HC4-306 for confident replacement, as verified in Honda OEM parts diagrams for 1995 and 1997 models .

• Proven Aftermarket Support: Leading aftermarket brands including WSM  and ProX  manufacture compatible piston and ring kits for these models, validating extensive aftermarket support for the Honda TRX300 platform.

• Premium Materials:

  • WSM rings feature the same design as originals for interchangeability and include a complete oil ring set with expander spacer .

  • The top ring features chrome-facing for superior heat resistance and wear longevity in high-revving engines.

• Oversize Option: The 0.25mm oversize rings allow you to reclaim engineered clearances in cylinders with minor wear (74.5mm final bore), restoring compression and combustion efficiency.

• Complete Ring Set: Includes top ring, second ring, and complete oil ring assembly with expander spacer for proper oil control .

Installation Notes:

• Ensure the cylinder is properly machined to the correct oversize specification (74.5mm final bore) before installation.

• Professional machining and assembly are recommended to ensure proper clearances and ring gap.

• Check ring end gap during installation to ensure it falls within factory specifications.

• This ring kit does not include the piston, wrist pin, or circlips – ensure your existing piston is in good condition or replace as necessary. For 0.25mm oversize, the matching Honda piston is part number 13102-HC4-305 . Piston pin (13111-HC0-000) and circlips (94601-17000) are also available separately .

• After installation, properly break in the engine according to manufacturer recommendations.

• Verify your exact model and year against the fitment table to ensure compatibility with your engine configuration.

Why Upgrade?
Worn piston rings can cause compression loss, excessive oil consumption, and reduced power output—leading to poor performance and potential engine damage. Restore your Honda TRX300 FourTrax engine's power and reliability with this quality aftermarket oversize piston ring kit, designed to keep you riding with confidence.

Order your piston ring kit today and get back on the trail with confidence.