Restore dependable top-end performance with the Namura FX-40045K Forged Top End Kit. Designed for select Yamaha 450cc four-stroke motorcycles, this standard-bore kit includes the essential components needed for a professional top-end rebuild. The forged piston is built for durability and consistent performance, while the included rings, wrist pin, retaining clips, top-end bearing, and gasket kit help simplify installation.
This Namura top-end kit fits 2003, 2004, and 2005 Yamaha YZ450F models, along with 2003, 2004, 2005, and 2006 Yamaha WR450F models. It features a 94.95 mm standard-bore piston and an 11:1 compression ratio for compatibility with the original engine configuration. Always inspect the cylinder, crankshaft, connecting rod, and related components before installation to confirm serviceability and proper fit.
Manufactured by Namura and identified by manufacturer part number FX-40045K, this kit is a practical replacement solution for worn or damaged top-end components. The complete component set supports efficient engine service while helping maintain proper compression, sealing, and piston movement. Follow the motorcycle manufacturer’s service procedures and verify application details before beginning installation.
Features:
- Forged piston: Durable standard-bore piston designed for reliable top-end service
- 94.95 mm standard bore: Matches the original cylinder specification for listed Yamaha applications
- 11:1 compression ratio: Supports the factory engine configuration
- Complete top-end kit: Includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit
- Fitment: Fits 2003-2005 Yamaha YZ450F and 2003-2006 Yamaha WR450F models
- Brand and part number: Namura FX-40045K
Fitment:
2003 Yamaha WR450F
2003 Yamaha YZ450F
2004 Yamaha WR450F
2004 Yamaha YZ450F
2005 Yamaha WR450F
2005 Yamaha YZ450F
2006 Yamaha WR450F