Yamaha YZ250F 01–07 & WR250F 01–12 83mm 290cc Big Bore Kit – Athena
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:
- Most parts ship next business day
- Modquad parts: Monday–Thursday dispatch
Made-to-Order Items:
- Custom swingarms & A-arms: 2–4 weeks
- EVP exhaust systems: 2–4 weeks
- Sneakers: 1–2 weeks
Stock Guarantee: Items marked "In Stock" ship immediately. Made-to-order items are built fresh for you.
Questions? Contact us—we respond within 24 hours.
