If you're dealing with a Yamaha YFM 350 or YFM 400 series ATV that's lost its edge on the trails due to worn piston rings, this OS 0.25 oversize piston ring kit is the precise solution you need. Engineered for models from 1987 through 2011, including popular variants like the FW and FB, this kit directly restores lost compression and seals out oil leaks for smoother, more powerful acceleration. By swapping out those fatigued rings, you'll breathe new life into your four-stroke engine, ensuring reliable performance whether you're navigating rugged terrain or tackling farm chores. As a mechanic who's seen firsthand how piston ring wear can lead to sluggish throttle response, excessive oil burn, and even engine misfires on demanding rides, I recommend this aftermarket replacement for its ability to tackle these issues head-on. It delivers a spot-on fit that minimises the risk of improper sealing, which is common with aging rings, and uses durable construction to handle the heat and pressure of high-revving engines. This kit stands out as a dependable choice for off-road enthusiasts, providing the exact balance of affordability and longevity that keeps your machine running strong mile after mile.

Comprehensive Vehicle Fitment

Product Specifications

OEM & Aftermarket Cross-Reference Information

What's Included

Based on standard piston ring kits for the YFM350/400 engine, this kit includes:

• Top ring

• Second ring

• Oil ring (included in complete sets)

Note: This is a piston ring kit only. It does not include the wrist pin, circlips, or piston. For a complete top-end rebuild, pistons and additional components are available separately from various manufacturers.

Why Choose This Aftermarket Piston Ring Kit?

• Extensive Vehicle Coverage: Compatible with a wide range of Yamaha YFM350 and YFM400 models spanning 1987 through 2011, including Big Bear, Kodiak, Bruin, Grizzly, Moto-4, Raptor, Warrior, and Wolverine variants .

• OEM Cross-Reference: Cross-references genuine Yamaha part numbers 4GB-11610-40-00 and 4GB-11610-00-00 for confident replacement .

• Proven Aftermarket Support: Pro-X Racing, a respected aftermarket brand, manufactures compatible piston rings for these models, manufactured in facilities that also supply OE manufacturers .

• Premium Materials: Pro-X products are manufactured using state-of-the-art electrofusion and steel crown manufacturing processes, producing exceptional finished products .

• Oversize Option: The 0.25mm oversize rings allow you to reclaim engineered clearances in cylinders with minor wear, restoring compression and combustion efficiency without requiring a full rebore to larger sizes.

• Cost-Effective Solution: By swapping out worn rings rather than undertaking a full engine rebuild, you can restore performance at a fraction of the cost.

Installation Notes:

• Ensure the cylinder bore is within specification for the 0.25mm oversize rings. A light honing is typically recommended when installing new rings.

• Professional machining and assembly are recommended to ensure proper clearances and ring gap.

• Check ring end gap during installation to ensure it falls within factory specifications.

• Follow manufacturer torque specifications and tightening sequences as outlined in the Yamaha service manual.

• This ring kit does not include the piston, wrist pin, or circlips – ensure your existing piston is in good condition or replace as necessary.

• After installation, properly break in the engine according to manufacturer recommendations.

• Verify your exact model and year against the fitment table to ensure compatibility with your engine configuration.

Why Upgrade?
Worn piston rings can cause compression loss, excessive oil consumption, and reduced power output—leading to poor performance and potential engine damage. Restore your Yamaha YFM350 or YFM400 engine's power and reliability with this quality aftermarket oversize piston ring kit, designed to keep you riding with confidence.

Order your piston ring kit today and get back on the trail with confidence.