This OS 1.00 Piston Ring Kit is a precision three-ring set designed to restore compression and sealing in the TRX300 FourTrax family (1988-2000) and its 4x4 variant. It’s engineered as a direct, no-mods replacement for the original rings, delivering reliable power, smoother operation, and less oil blow-by on rugged trails and demanding farm work. When rings wear or seating becomes compromised, this kit helps recover throttle response, reduce oil consumption, and reestablish peak top-end performance.

Built as a durable aftermarket alternative, this ring kit targets the common wear points in the TRX300 top end. It provides a dependable rebuild path when aging engines show compression fade, increased oil leakage into the combustion chamber, or power loss under load. With a focus on long-term sealing and consistent compression, it’s a practical choice for riders and land managers who rely on steady performance in tough conditions.

Comprehensive Vehicle Fitment

Product Specifications

OEM & Aftermarket Cross-Reference Information

What's Included

This kit includes the essential rings required to restore sealing and compression on the TRX300 top end.

• Top Compression Ring
• Second Compression Ring
• Oil Control Ring

*Wrist pin, circlips, and top-end gasket kit are not included in this piston ring set.*

Why Choose This Aftermarket Replacement?

• Direct-Fit Compatibility: Precisely matched to the TRX300 1988-2000 engine geometry for straightforward installation and seating.
• OEM Cross-Reference: Aligns with Honda 13051-HC4-306 and 13041-HC4-306, ensuring serviceable replacement options and known fitment.
• Premium Materials: Chrome-plated steel rings engineered to resist heat and wear in the TRX300 top end for durability in rugged use.
• 3-Ring Configuration: Top and second compression rings plus an oil control ring deliver robust sealing and oil management across the bore.
• Performance Restoration: Reestablishes compression, reduces oil consumption, and restores throttle response after ring wear.
• Cost-Effective Replacement: A reliable aftermarket option that maintains OEM-fit performance at a more approachable price.

Installation Notes:

• Carefully inspect the cylinder bore for ridge wear and measure bore diameter to confirm standard 74.00 mm or oversize bore as applicable before assembly.
• Clean grooves thoroughly and verify there is no scoring that could mis-seat the rings; remove any carbon buildup from the piston lands.
• Orient the rings correctly: install the Top Compression Ring, followed by the Second Compression Ring, then the Oil Control Ring; stagger the end gaps to avoid continuous gaps in a single line.
• Lubricate all rings and the piston skirts with clean engine oil before installation to prevent dry starts and scoring.
• Use a proper ring compressor when sliding the rings onto the piston to prevent ring deformation; ensure the rings are fully seated in their grooves.
• After reassembly, perform a careful break-in period with gradually increasing throttle to allow rings to seat and seat grooves to wear evenly.

Why Upgrade?

Running a worn piston ring set typically leads to reduced compression, increased oil consumption, and diminished throttle response. This replacement restores proper ring seating and sealing, reducing blow-by and bringing back reliable power for both trail riding and farm work.