Description
The DEF Racing Stage 3 Cylinder Head Porting Service for the 2019-2026 Yamaha YZ250F was developed to maximize horsepower, torque and combustion efficiency through the entire power curve. Utilizing a high-precision airflow bench and advanced CNC technology, we reshape intake and exhaust ports as well as a major cleanup of the chamber face to improve combustion efficiency and airflow.
Turn-Around Time
- Estimated 3-5 weeks from the date we receive the head
Service Overview
- Teardown, cleaning & vapor blasting
- Thorough inspection of cylinder head
- Remove OEM original seats and guides & install our Moldstar90 seats and Moldstar22 valve guides
- CNC Port w/hand finish of the walls and combustion chamber face
- Final valve seat profile applied on a CNC machine
- Deck cylinder head to target combustion chamber volume and increasing compression
Port Design
- Optimized exhaust and intake flow and velocity
- Power gains across all RPMs, with significant improvements in the mid to high RPM range
- Epoxied intake port improves engine torque and response
- OEM intake manifold spigot is port-matched for optimal performance
Valve Seats and Valve Guides
- CNC machined valve seat profiles
- Valve seats are upgraded to Moldstar90
- Valve guides are upgraded to Moldstar22
- Pressure testing for leak detection
- Increased durability and performance
- Enhanced heat transfer improves performance and durability
Customer Instructions
- Purchase the cylinder head service
- Send cylinder head & intake manifold to our shop (You are responsible for shipping to us)
- Place a copy of purchase order form in with your cylinder head
- Make sure all your contact details are in the box!
- We will call you when we receive your head to answer any questions and provide a more accurate lead time
- Return shipping cost is already included, and we will handle the logistics for returning to you.
NOTE: Cylinder head port service does not include any valve train parts!
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