OS 0.75 oversize piston kit for the 228cc Bayou ATV family (2003–2011) restores peak compression and power after top-end wear. The kit features a 69.75 mm bore (0.75 mm oversize) and comes complete with a piston, rings, wrist pin and circlips for a ready-to-install rebuild. Designed to deliver factory-like reliability in off-road conditions, this top-end refresh helps restore lost performance and smooth, dependable power across the full 2003–2011 model span.

With MOS2-coated skirt technology and a cast aluminum alloy piston, this aftermarket replacement reduces friction, improves heat resistance, and promotes longer engine life under harsh trail, farm, or job-site duty cycles. Because it mirrors OEM-style dimensions, it installs cleanly without modifying the engine, delivering durable performance when you need to trust your ATV for demanding work or rough-terrain rides. This kit is a reliable choice for riders who demand restoring power and consistency without the OEM price tag.

Comprehensive Vehicle Fitment

Product Specifications

OEM & Aftermarket Cross-Reference Information

What's Included

This kit includes the essential components for a proper top-end refresh.

• Piston
• Rings
• Wrist Pin
• Circlips

Related parts such as gaskets or seals are not included.

Why Choose This Aftermarket Replacement?

• Direct-Fit Compatibility: Oversize 0.75 mm piston matches a 69.75 mm bore for precise ring sealing and cylinder clearance, ensuring reliable top-end performance.
• OEM Cross-Reference: Original part references are listed to help verify compatibility across model years and trims.
• MOS2-coated skirt: Reduces friction, lowers heat buildup, and improves startup reliability under dusty, hot, off-road use.
• Premium Cast Aluminum: Durable, lightweight piston material designed for repeated heat cycling and harsh conditions.
• Complete Top-End Refresh: Includes piston, rings, wrist pin and circlips for a full rebuild kit, saving time and avoiding missing parts.
• Factory-Style Dimensions: Maintains OEM-like tolerances to preserve original performance and reliability without paying OEM prices.

Installation Notes:

• Pre-Check Bore: Confirm cylinder bore is 69.75 mm before installation; any out-of-tolerance wear may require honing or re-boring as per service manual.
• Rings & Gaps: Check top and second ring end gaps according to the service manual; replace if out of specification to ensure proper sealing.
• Lubrication: Apply light engine assembly lube to the piston skirts and rings during installation to prevent dry starts.
• Wrist Pin & Circlips: Install wrist pin with proper end clearance and seat circlips securely in grooves; verify with a small twist to ensure they won’t back out during operation.
• Orientation & Clearances: Align piston orientation marks as indicated by OEM drawings; verify piston-to-wall clearance with feeler gauges if required by service manual.
• Clean Assembly: Thoroughly clean the cylinder, head and oil passages; remove all debris to avoid scoring or oil starvation on first startup.

Why Upgrade?

Worn piston assemblies compromise compression, reduce power, and can accelerate cylinder wear or cause overheating under load. Upgrading to the OS 0.75 oversize kit restores ring sealing, improves heat management, and brings the engine back toward factory-like performance, giving you reliable power on the trail or job site.