Cylinder Works Big Bore Cylinder Kit 21002-K01 — Yamaha YZ250F / WR250F 2001-2013

Product Description

Transform your classic 250cc machine into a high-torque powerhouse with the Cylinder Works Big Bore Cylinder Kit. Engineered to increase your displacement to 270cc, this kit is the perfect performance upgrade to revitalize an older YZ250F or WR250F, offering a noticeable boost in mid-range punch and overall engine output. This complete, bolt-on solution requires no machine work, making it the most efficient way to achieve significant performance gains.

Each kit is proudly made in the USA and includes a high-quality cylinder featuring a durable nickel silicon carbide sleeve for reduced friction and improved heat dissipation. We pair this with matching Vertex pistons to guarantee maximum longevity, consistent compression, and reduced engine noise. With a 12.5:1 compression ratio, you will enjoy improved throttle response and stronger power delivery on every ride.

Top Features: Cylinder Works Big Bore Kit

• Increases displacement to 270cc for significant power gains
• Includes matching Vertex pistons for optimal longevity and low noise
• Advanced nickel silicon carbide cylinder coating for superior heat management
• Complete kit: includes cylinder, pistons, rings, pin, clips, and gaskets
• Precision-engineered, bolt-on design—no machine work required
• Proudly made in the USA

Please review the detailed compatibility data below to ensure an exact fitment match for your motorcycle before finalizing your purchase.

Fitment List

Frequently Asked Questions

Q: Will this kit affect the reliability of my engine?
A: Cylinder Works kits are engineered to be extremely reliable. By using high-quality Vertex pistons and nickel silicon carbide coatings, this kit is designed to handle the increased displacement while maintaining factory-like longevity when maintained properly.

Q: Do I need to re-jet my carburetor?
A: Yes. Because you are increasing your displacement to 270cc, your engine will require more fuel. You should re-jet your carburetor to ensure the air/fuel ratio is correct for the increased capacity.

Expert Pro-Tip: When installing a big bore kit, proper ring break-in is essential. Do not let the bike idle for long periods during the first heat cycle. Instead, take it for a moderate ride, varying the throttle—avoid sustained high RPMs initially—then let it cool down completely. This procedure helps the rings seat properly against the cylinder wall for maximum compression.

Recommended Pairings:
o Yamaha YZ250F Performance Parts
o Premium Motorcycle Chemicals
o Yamaha 4-Stroke Performance Parts

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