Yamaha YFZ450R 400cc De-Bore Conversion Kits & Components
The BNR Motorsports 400cc De-Bore Conversion Series is designed for riders looking to build a competitive and reliable 400cc Yamaha YFZ450R. Whether you're purchasing a complete conversion kit or replacement components, every part is engineered to work together for maximum performance.
Serialized Cylinder Identification
Every BNR Motorsports 400cc de-bore cylinder is permanently engraved with a unique serial number for quality control and product traceability.
Important Information
All Yamaha YFZ450R 400cc de-bore engines require a Vortex ECU programmed specifically for the 400cc conversion. The factory ECU cannot properly operate a de-bore engine because the fuel and ignition requirements are significantly different from a stock 450cc engine.
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If you already own a Vortex ECU, you can send it to BNR Motorsports to be reflashed for your 400cc engine combination.
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If you do not own a Vortex ECU, select the Kit with Vortex ECU option and we'll supply a new ECU that is custom programmed for your build.
When ordering a Vortex ECU or ECU reflash, please provide your complete engine specifications, including camshaft, exhaust system, intake modifications, and any other performance upgrades. This allows us to create a calibration specifically for your ATV.
Available Options
Complete 400cc De-Bore Kit
Includes:
- Note: A Vortex ECU is required for all 400cc de-bore conversions
Complete 400cc De-Bore Kit with Vortex ECU
Includes:
- Precision-machined 400cc cylinder
- BNR Wiseco 400cc forged piston (includes Wiseco rings, wrist pin, and circlips)
- 400cc de-bore head gasket
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New Vortex ECU professionally programmed by BNR Motorsports specifically for the 400cc de-bore engine
Each Vortex ECU is custom flashed to match your ATV's engine combination and performance modifications, providing optimized fuel and ignition mapping for maximum power, crisp throttle response, and long-term reliability.
400cc De-Bore Head Gasket
Replacement head gasket designed specifically for BNR Motorsports 400cc de-bore engine builds.
400cc De-Bore Piston
Replacement piston for BNR Motorsports 400cc de-bore engine builds.
ContactÂ
Call: (330) 549-9799
Text: (330) 774-1123
Email: bnrmotorsports@hotmail.com