Vertex Top End Piston Kit VTK22520B (53.94mm) — Yamaha YZ125 1998-2000

Vertex Top End Piston Kit VTK22520B — Yamaha YZ125 1998-2000 (53.94mm)

Product Description

Refresh your Yamaha YZ125 top end with the complete Vertex VTK22520B Top End Piston Kit. Designed for 1998–2000 models, this all-in-one kit simplifies your maintenance process by bundling a high-quality cast replica piston with all the necessary top-end gaskets and the essential wrist pin bearing.

Vertex cast pistons are crafted from an 18% silicone-content gravity-cast aluminum alloy, providing superior dimensional stability under the high heat of 2-stroke engine operation. The Molybdenum Disulphite (MoS2) skirt coating minimizes friction, accelerates break-in, and provides lasting protection against scuffing. With this comprehensive kit, you can be confident that you have everything required to restore factory compression and throttle response.

Top Features: Vertex Top End Piston Kit

• All-in-One Solution: Includes piston, rings, wrist pin, circlips, top-end gaskets, and a wrist pin bearing for a complete refresh.
• Factory Precision: Designed as a direct cast OE replacement piston for exact compatibility.
• Advanced Material: Gravity-cast aluminum alloy with 18% silicone stabilizes the piston shape under extreme temperatures.
• Moly-Coated Skirt: Coated with Molybdenum Disulphite for reduced friction, quicker break-in, and added protection against scuffing.
• T-5 Heat Treated: Undergoes a complete T-5 hardening and tempering cycle to maximize structural integrity and lifespan.

Please confirm your cylinder bore size before ordering to ensure the correct piston fitment.

Product Specs

• Piston Diameter: 53.94 mm
• Cylinder Diameter: 54.00 mm
• Displacement: 125 cc
• Engine Type: 2-Stroke

Fitment List

Year Range	Vehicle Model
1998-2000	Yamaha YZ125

Frequently Asked Questions

Q: What is the benefit of including the wrist pin bearing in the kit?
A: The wrist pin bearing is a high-wear component that endures immense loads. Replacing it with every piston change prevents premature failure that could otherwise destroy your new piston and cylinder. Including it ensures a safe, reliable rebuild.

Expert Pro-Tip: Before installing your new rings, always check the ring end gap in the cylinder to ensure it falls within the manufacturer's specified range. This ensures optimal compression and prevents the rings from binding as the engine heats up.

Recommended Pairings

• Essential Off-Road Motorcycle Tools
• High-Performance Premix & Gear Oils

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