Restore peak compression in a 450cc ATV engine by installing the OS 1.00 piston ring kit designed for the YFM450 family. This oversize 1.00 mm kit clamps down in the piston grooves to seal provenly, reduce oil blow-by, and deliver consistent power across trail work or farm duty. Engineered to fit multiple high-mileage models from the early 2000s through the mid-2010s, it’s the practical, cost-effective route to refresh compression without replacing the entire piston assembly.

The OS 1.00 kit tackles common wear like ring-land damage and oil leakage that creep into aging engines. By restoring proper ring seating and sealing, it supports reliable cold starts, steady throttle response, and predictable power delivery when you’re pulling stumps in the field or pushing through rough single-track. Choose this aftermarket replacement for a factory-like restoration at a fraction of the OEM price, with a focus on durability and precise fit.

Comprehensive Vehicle Fitment

Product Specifications

OEM & Aftermarket Cross-Reference Information

What's Included

This kit includes the essential rings to restore compression on the affected models:

• Top compression ring
• Second compression ring
• Oil control ring

Note: This kit does not include the piston, wrist pin, clip(s), or circlips.

Why Choose This Aftermarket Replacement?

• Direct-Fit Compatibility: Precisely matched to the YFM450FA/FG/FX and YXR450F ring grooves and piston sizes for reliable install and sealing.
• OEM Cross-Reference: Uses the Yamaha 5ND-11607-00-00 specification as the anchor reference, ensuring correct aftermarket substitution.
• Premium Materials & Precision: Engineered to restore sealing surfaces and control oil blow-by, helping maintain steady compression under load.
• Performance Restoration: Reinstates reliable throttle response and cold-start performance by restoring ring seal in high-mileage engines.
• Cost-Effective Alternative: Delivers OEM-like performance at a fraction of the price, reducing overall rebuild costs.
• Trail- and Farm-Grade Durability: Designed to endure the grime, dust, and load of off-road and field-use environments.

Installation Notes:

• Thoroughly clean ring lands and cylinder grooves before re-assembly to ensure proper seating and sealing.
• Use a proper ring expander and a ring compressor to avoid scratching or bending rings during installation.
• Check the end-gap of each ring with a feeler gauge and ensure it matches OEM or the specified aftermarket tolerances.
• Lubricate the rings lightly with clean engine oil before installation to reduce initial wear during startup.
• Install the top compression ring with the marked side facing up and align ring gaps to avoid alignment with the piston pin or exhaust port gaps.
• Carefully insert the piston into the cylinder, keeping ring grooves aligned and avoiding ring twist or pinching.

Why Upgrade?

Running a worn piston ring set can lead to compression loss, increased oil consumption, and reduced power. Upgrading to the OS 1.00 piston ring kit restores proper sealing and compression, delivering reliable power and cleaner operation across demanding trail and farm tasks.