This OS 0.50 Piston Kit is an aftermarket replacement designed specifically for the Honda TRX 500 Foreman and Rubicon line, covering 2005 through 2011 models. It features a +0.50 mm oversize bore to restore compression and bring the engine back toward its original power characteristics after wear. Engineered to meet or exceed Honda tolerances, this kit is built to withstand the rigors of trail riding and farm duty while delivering reliable, consistent performance on the job.

The value of this replacement goes beyond mere parts swap: the oversize piston compensates for bore wear, helping to maintain effective sealing, steady compression, and strong low-to-mid RPM response. Constructed as a forged alloy piston, it emphasizes durability and long-term reliability under demanding use, making it a sound choice for riders who push their Foreman/Rubicon machines on dirt trails or rural work.

Comprehensive Vehicle Fitment

Notes: Fits are aligned with the Foreman/Rubicon 500 platforms across the listed years, ensuring compatibility with the 0.50 mm oversize piston kit for proper compression restoration.

Source alignment: model and year coverage reflects aftermarket references for TRX500 Foreman/Rubicon 2005–2011 variants.

Product Specifications

Additional context: forged alloy pistons are commonly chosen for aftermarket OS kits to balance strength with light weight, helping maintain ring sealing and piston stability under load.

OEM & Aftermarket Cross-Reference Information

These cross-reference entries help validate compatibility across regional Honda part catalogs and confirm the aftermarket kit aligns with established OEM references.

What’s Included

OS 0.50 Piston Kit contents tested and packaged for installation compatibility include:

• Piston with OS +0.50 mm oversize
• Rings matched to the piston
• Wrist Pin
• Circlips for wrist pin retention

Note: Related top-end components such as the cylinder, head gasket, or other seals are not listed as included and may be required separately depending on your rebuild needs.

Why Choose This Aftermarket Replacement?

• Direct-Fit Compatibility: Precisely matched to Honda TRX500 Foreman/Rubicon models from 2005–2011 for a straightforward install.
• OEM Cross-Reference: Cross-referenced with Honda OEM part numbers to ensure proper fit and performance.
• Premium Materials: Forged alloy piston designed for durability and reliable sealing under heavy use.
• Performance Restoration: Restores compression and power lost from bore wear, returning engine response to near-original levels.
• Trail- and Farm-Ready: Built to withstand rugged terrain and demanding workloads common on trails and rural properties.
• Cost-Effective Alternative: A practical, cost-conscious option compared to OEM replacements without compromising essential specs.

Installation Notes:

• Verify bore condition and determine if cylinder honing or boring is required to properly accept the +0.50 mm oversize piston.
• Lubricate the piston, rings, and wrist pin with assembly lube before insertion to prevent dry starts.
• Install piston rings with correct orientation and stagger ring gaps (do not align gaps vertically) to optimize sealing.
• Ensure wrist pin is fully seated and the circlips are securely installed to avoid wrist pin movement during operation.
• Replace base and head gaskets as part of the rebuild and clean all mating surfaces to ensure a proper seal.
• Follow a cautious break-in procedure after installation to seat rings and establish proper ring seating.

Why Upgrade?

Running a worn piston kit on a Honda TRX 500 Foreman/Rubicon can lead to compression loss, reduced power, and uneven combustion, which degrades drivability on trails and in field work. Upgrading to the OS 0.50 piston kit restores compression, sharpens throttle response, and rebuilds reliable performance for tough terrain and daily farm tasks.