Yamaha YZ125 / YZ125X Athena 144cc Big Bore Kit (2005-2022)
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Turn your Yamaha YZ125 into a 144cc race weapon with the Athena Big Bore Kit. Designed for 2005-2021 YZ125 and 2020-2022 YZ125X, this kit adds serious horsepower and torque while maintaining OEM-level reliability. Includes all top-end components, from cylinder to piston and gaskets, with Athena's proven engineering and materials.
✓ Fits:
- Yamaha YZ125 (2005-2021)
- Yamaha YZ125X (2020-2022)
✓ Features:
- Boosts displacement from 125cc → 144cc for major power gains
- Aluminum cylinder with nickel-carbide coating for maximum durability
- Includes complete Athena top-end kit with piston, gaskets, head, and valves
- Race-ready with improved torque and top-end pull
- Direct OEM fitment - designed specifically for YZ125 and YZ125X
✓ What's Included:
- Athena 58mm Nikasil Big Bore Cylinder (144cc)
- Athena Coated Piston Kit (Piston, Rings, Wrist Pin, Circlips)
- Athena Complete Top End Gasket Set
- Athena Cylinder Head w/ Removable Bronze Dome
- Athena Head Stud Kit
- Athena High-Performance Anodized Power Valves (OEM valves not compatible)
- All components brand new, covered by Athena's warranty
Ships fast from DuneGoonShop!
📦 Shipping Information
In-stock items ship next business day. ModQuad parts dispatch Monday through Thursday.
Made-to-order and custom powder coat items show their lead time at the top of this page, right next to the truck icon. These are built fresh for you, so timing varies by brand and current backlog.
Need something by a specific date? Call us at 541-668-7503 before ordering and we will check stock and ETA on that exact part. We can often point you to an in-stock alternative from another distributor.
Questions? Contact us, we respond within 24 hours.
