If you're tackling a top-end rebuild on your Yamaha YFM 400 FB or FW Manual from 1993 to 2012, this OS 0.50 piston ring kit is the precise aftermarket solution you need to restore lost compression and get your engine running like new again. Designed specifically for these rugged ATV models, it addresses the common wear that leads to reduced power and efficiency over years of trail riding or farm work. By swapping in this reliable oversize ring set, you'll regain that responsive throttle and prevent further engine strain, making it an essential upgrade for maintaining peak performance on demanding terrains.
What sets this aftermarket piston ring kit apart is its ability to tackle the specific wear-and-tear issues like cylinder bore enlargement and ring seal degradation that plague high-mileage Yamaha YFM 400 engines, ensuring your machine doesn't let you down mid-ride. This replacement delivers a spot-on fit that mimics OEM standards while using enhanced materials to withstand the heat and stress of off-road conditions, making it a smart choice for both recreational riders and hardworking farmers. With its focus on durability and precise engineering, you'll experience smoother operation and extended engine life, all without the premium price of original equipment parts.
Comprehensive Vehicle Fitment
Product Specifications
OEM & Aftermarket Cross-Reference Information
*OEM cross-reference numbers are provided for reference purposes only. These numbers indicate the lineage of oversize rings; always verify your final bore size (83.50mm) before ordering.*
What's Included
This OS 0.50 oversize piston ring kit ships with the essential components to rebuild one Yamaha YFM 400 cylinder.
Note: This is a piston ring kit only. It does not include the piston, wrist pin, circlips, or gaskets.
Why Choose This Aftermarket Replacement?
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Precise Oversize Fit: Specifically designed for engines that have been professionally overbored to a final size of 83.50 mm (OS 0.50), ensuring correct ring gap and optimal sealing.
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OEM Cross-Reference: Follows the oversize progression of OEM rings, making it the logical choice for a professionally rebuilt cylinder corresponding to piston reference 4GB-11636-00-00.
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Restores Lost Compression: New, properly gapped rings restore cylinder pressure, directly addressing power loss, blow-by, and high oil consumption.
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Durable Construction: Features a high-quality chrome-faced top ring for superior heat resistance and wear longevity, built to withstand the demands of high-RPM operation and tough terrain.
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Complete Ring Set: Includes all three rings (top, second, and oil ring set) required for a complete and effective piston seal.
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Cost-Effective Engine Refresh: Delivers reliable performance at an aftermarket price, ideal for extending the life of your machine without a full OEM investment.
Installation Notes:
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Verify Bore Size: This is critical. Confirm the engine cylinder has been professionally overbored to the final size of 83.50 mm before ordering. This kit is not for standard or other oversize bores.
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Professional Machining Required: A proper overbore and hone by a qualified machine shop is essential for the new rings to seat correctly and achieve a long-lasting seal.
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Check Ring End Gap: Always measure and adjust ring end gaps according to the service manual specifications for the 83.50mm bore.
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Lubricate During Assembly: Lubricate the piston, rings, and cylinder wall with clean engine oil or assembly lube prior to installation.
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Orient Rings Correctly: Ensure rings are installed with the correct orientation (if any) and that the ring gaps are staggered according to the service manual to prevent blow-by.
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Follow Service Manual: Adhere to all torque specifications and break-in procedures outlined in the Yamaha service manual.
Why Upgrade?
Worn piston rings on a Yamaha 400cc quad lead to noticeable compression loss, reduced power, and increased oil consumption. This OS 0.50 oversize ring kit restores proper ring seal and oil control, renewing reliable power and smooth operation, and preventing the risk of a sudden failure on the trail or in the field.
Order your piston ring kit today and get back on the trail with confidence.
