OS 0.25 Oversize Piston Ring Kit for LT-A400/LT-F400 Eiger and KingQuad engines restores compression and oil control on 2002–2017 models. This top-end kit cycles fresh rings into the 376cc SOHC single-cylinder configuration to re-seal the combustion chamber and revitalize power and reliability in demanding trail and farm work. Built to precise tolerances for a reliable, field-ready rebuild that fits directly into the existing bore and ring grooves.

Designed to combat the wear and heat that accumulate after years of hard use, this oversize ring set addresses compression loss and increasing oil consumption caused by tired rings. It provides a cost-conscious, dependable alternative to OEM parts while preserving performance in tough off-road and agricultural environments. Expect restored sealing, reduced blow-by, and extended service life when you install this OS 0.25 kit with proper top-end preparation.

Comprehensive Vehicle Fitment

Product Specifications

OEM & Aftermarket Cross-Reference Information

What's Included

This OS 0.25 piston ring kit is designed to restore top-end sealing on Suzuki 400 engines. It includes the essential ring set needed to rebuild the top end for LT-A400/LT-F400 platforms.

• Top compression ring
• Second compression ring
• Oil ring

Why Choose This Aftermarket Replacement?

• Direct-Fit Compatibility: Precisely sized for LT-A400/LT-F400 2002–2017 engines with an OS 0.25 bore increase.
• OEM Cross-Reference: Backed by OEM cross-reference numbers to help verify compatibility across Suzuki top-end parts.
• Premium Materials: High-grade alloy steel rings machined to tight tolerances for reliable sealing and long service life.
• Performance Restoration: Restores compression and reduces blow-by, improving power delivery and throttle response.
• Cost-Effective Reliability: A durable aftermarket option that keeps the engine performing well between full top-end rebuilds.
• Field-Ready Durability: Built to withstand heat and grime from trail and farm work.

Installation Notes:

• Pre-install bore and ring groove inspection: Check bore wear and ring grooves; verify bore diameter is within OS limits before assembly.
• Rings installation order and orientation: Install the Top compression ring, then the Second compression ring, followed by the Oil ring in their proper grooves.
• Lubrication: Lightly lubricate all rings and the piston with clean engine oil prior to installation.
• Ring end gaps: Ensure end gaps are offset around the circumference to avoid continuous gaps at any single point.
• Tooling and handling: Use a proper ring expander and avoid bending or twisting the rings during installation.
• Cleanliness: Thoroughly clean the piston, rings, and cylinder surfaces; remove any debris from grooves and oil passages.
• Break-in and checks: After assembly, perform a gentle break-in, then run a controlled compression test and monitor oil consumption.

Why Upgrade?

Worn piston rings lose tension over time, leading to compression loss and excessive oil burning. Upgrading to this OS 0.25 kit restores a proper seal, reducing blow-by and returning engine performance and reliability for demanding off-road and farm use.