BOLT YZ.EX.125CC Exhaust Hardware Kit 2001-2022 Yamaha YZ125 YZ125X

A leaking two-stroke exhaust doesn't just make a mess of your engine—it actively robs you of critical backpressure and throttle response. The BOLT YZ.EX.125CC Exhaust Hardware Kit is the ultimate OEM Replacement for Yamaha small-bore riders who demand a factory-level seal. At Moto-House MX, we know that maintaining a tight seal at the cylinder manifold is the only way to keep your YZ running at peak efficiency and prevent the dreaded "spooge" from coating your frame.

Engineered for Racing Performance, this kit features model-specific green Viton® rubber O-rings that are far superior to standard seals. Viton® is specifically chosen for its ability to withstand the extreme temperatures of a high-revving 125cc engine without hardening or cracking. Paired with high-tension exhaust springs and a fresh pipe-to-silencer coupler, this hardware ensures your expansion chamber stays secure and sealed through the roughest sections of the track or trail.

Top Features: BOLT YZ.EX.125CC Exhaust Kit

• Viton® High-Temp O-Rings: Includes model-specific green Viton® rubber seals designed to resist extreme heat and chemical degradation.
• Complete System Refresh: Provides high-tension pipe springs and a durable pipe-to-silencer coupler for a total exhaust overhaul.
• Precision Yamaha Fitment: Engineered specifically for the Yamaha YZ125 and YZ125X two-stroke platforms.
• Heavy-Duty Durability: Built to withstand the constant vibration and thermal cycling of competitive off-road riding.
• Optimized Seal: Restores engine backpressure and prevents exhaust leaks at the manifold and silencer junctions.

Fitment List

Frequently Asked Questions

Q: Why are the O-rings in this kit green?
A: The green color indicates they are made from Viton® rubber. This material has a much higher heat rating than standard black nitrile O-rings, which is essential for the high exhaust gas temperatures of a two-stroke.

Q: Should I replace my exhaust springs even if they aren't broken?
A: Yes. Over time, heat and vibration cause springs to lose their tension (stretch), which leads to vibration-induced wear on your exhaust manifold and potential leaks.

Q: Does this kit include the coupler that connects the pipe to the silencer?
A: Yes, this kit includes the rubber pipe-to-silencer coupler, the Viton® O-rings for the cylinder side, and the necessary tension springs.

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