Yamaha YZ250F 01–07 & WR250F 01–12 83mm 290cc Big Bore Kit – Athena (2001-2012)
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Transform your YZ250F/WR250F into a 290cc torque monster. Bolt-on install, no machining—just explosive mid-range power and race-proven durability.
The Athena P400485100012 is a complete 83mm big bore race kit that takes 2001–2007 Yamaha YZ250F and 2001–2012 Yamaha WR250F from 249cc to 290cc (+41cc). Nickel-carbide cylinder, Factory Works porting, 12.5:1 forged piston, hard-anodized power valves. Cylinder head not included.
What's Included
- 83mm Nickel-Carbide Cylinder – Factory Works porting
- Forged Piston Kit – 12.5:1 compression, molybdenum coating, rings, pin, clips
- Hard-Anodized Power Valves – high-flow, non-OEM
- Athena Top-End Gasket Set – head/base gaskets, seals, hardware
Key Features
- 83mm big bore — +41cc (249cc → 290cc)
- Nickel-carbide plating — extreme durability, low friction
- Larger water jackets — superior cooling under race load
- Factory Works porting — max airflow, pro-tuned performance
- 12.5:1 forged piston — explosive mid-top power
- Hard-anodized power valves — faster response, longer life
- Made in Italy — race-proven precision
Fitment
- 2001–2007 Yamaha YZ250F
- 2001–2012 Yamaha WR250F
Install Notes
- Reuses OEM cylinder head (not included)
- Advanced install — engine disassembly required
- Jetting/tuning recommended for optimal performance
📦 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.
