Cylinder Works Big Bore Cylinder Kit – Yamaha YZ450F (2003–2005) / WR450F (2003–2006)

Description

Boost displacement and power with the Cylinder Works Big Bore Cylinder Kit (P/N 23001-K02 / 0931-0426), designed as a complete bolt-on performance upgrade for your Yamaha YZ450F or WR450F.

This 98.00mm big bore cylinder increases displacement to 478cc, delivering improved torque and throttle response without requiring case machining. Each kit features a Nickel Silicon Carbide (NiCom) plated cylinder, paired with a precision Vertex piston kit and top-end gaskets for a full top-end refresh.

Perfect for riders seeking more low-end grunt and midrange punch while maintaining OEM reliability and fitment.

What’s Included

✅ Cylinder – Nickel Silicon Carbide plated, ready to install
✅ Vertex Piston Kit – piston, rings, wrist pin, and clips
✅ Top-End Gasket Kit – head, base, and exhaust gaskets included

(No machine work required.)

Fitment

📦 Fits the following models:

• Yamaha YZ450F (2003–2005)

• Yamaha WR450F (2003–2006)

Key Features

• +3.00mm big bore (98.00mm total bore) for 478cc displacement

• 12.5:1 compression ratio – stronger midrange power

• Cylinder made in the USA, machined to OEM spec

• Nickel Silicon Carbide sleeve for reduced wear and superior heat dissipation

• Includes Vertex piston kit and gaskets for a complete top-end rebuild

• Bolt-on installation — no replating or case boring required

Bore Size: 98.00mm (+3.00mm)
Displacement: 478cc
Compression Ratio: 12.5:1
Engine Type: 4-Stroke
Weight: 4.6 lb

Warranty Info

🛡️ Backed by Cylinder Works Limited Manufacturer Warranty
All components meet or exceed OEM quality standards. Professional installation recommended.

Price & SKU

💲 Retail Price: $808.95
SKU: 0931-0426 / 23001-K02
Estimated Shipping Weight: 4.6 lb
Handling: Ships next business day