PAIR Block-Off Plates are designed to block the factory PAIR (Pulsed Secondary Air Injection) system found on many motorcycles. Riders commonly install PAIR block-off plates when adding performance exhaust systems, ECU tuning, or other engine modifications to help reduce unwanted exhaust popping and support proper tuning. Brock's Performance PAIR Block-Off Plates are designed for specific motorcycle applications and developed to provide a clean, reliable solution for performance-focused riders.
What Is the PAIR System and Why Does It Cause Problems?
The Pulsed Secondary Air Injection (PAIR) system introduces fresh atmospheric air directly into the exhaust ports during operation. On a stock motorcycle running the factory tune, this system helps burn off unburned hydrocarbons in the exhaust to meet emissions standards.
The problem shows up as soon as you install an aftermarket exhaust or an ECU flash. The PAIR system continues to inject fresh air into the exhaust, but the timing, tuning, and airflow have all changed. The result is loud popping and cracking on deceleration, an inconsistent lean condition in parts of the RPM range, and fueling behavior that fights against whatever tune has been installed. It also causes the ECU to read false air, which can confuse fuel trim calculations on some platforms.
Installing block-off plates seals the PAIR ports at the cylinder head, giving the ECU and tune a clean, consistent picture of what's happening in the exhaust. That's why PAIR removal is a standard step in almost every serious performance build on a PAIR-equipped bike.
Why Riders Install PAIR Block-Off Plates
PAIR block-off plates are one of the most common supporting modifications installed alongside performance exhaust and tuning work.
Riders install them to:
- Eliminate the decel popping and cracking that appears after installing an aftermarket exhaust
- Remove the false air source that fights against ECU tuning and fuel controllers
- Support proper fueling and throttle response across the RPM range
- Simplify the engine bay by removing the factory PAIR hoses and hardware
- Complete an aftermarket exhaust install with a matched, cleanly tuned system
For most PAIR-equipped motorcycles, block-off plates are a required supporting modification, not an optional one, when adding an aftermarket exhaust or ECU tune.
Performance Upgrades Work Best as a System
Common supporting upgrades include:
When these components work together, riders can create a more complete and effective performance package.
Why Choose Brock's PAIR Block Off Plates?
A block-off plate is a simple part with a specific job. Ours are precision-machined to seal the PAIR ports cleanly on the specific motorcycles they support, with the correct thickness, gasket surface, and hardware to install correctly and stay sealed under heat and vibration. We stock them because they're a standard step in almost every serious performance build we support, and because a properly sealed PAIR delete is one of the small details that separates a good exhaust install from a great one.
FAQs
What does a PAIR block-off plate do?
A PAIR block-off plate seals the PAIR ports on the cylinder head, permanently blocking the fresh-air source used by the factory PAIR system to inject air into the exhaust. That eliminates decel popping, lean conditions in the exhaust, and tuning conflicts that arise when the PAIR system conflicts with an aftermarket exhaust or ECU flash.
Will PAIR block-off plates stop exhaust popping?
In most cases, yes. Decel popping on a bike with an aftermarket exhaust is most often caused by fresh air from the PAIR system meeting unburned fuel in the hot exhaust. Sealing the PAIR ports removes the fresh-air source, which usually eliminates or dramatically reduces the popping. Popping can also be caused by a lean tune, so pairing block-off plates with an ECU flash or fuel controller usually delivers the cleanest result.
Do I need PAIR block-off plates with an aftermarket exhaust?
For most PAIR-equipped sportbikes, yes. It's one of the most common tuning issues we help customers diagnose. If you've installed an aftermarket exhaust and your bike now pops on decel, runs inconsistently, or fights your tune, PAIR block-off plates are usually the first fix.
Are PAIR block-off plates required for an ECU Flash to work correctly?
Not required in every case, but strongly recommended for the cleanest tuning result. A Brock's ECU Flash calibrates fueling and ignition to your bike's actual configuration. Leaving the PAIR system connected introduces a variable the flash can't control, which is why most performance builds pair the flash with block-off plates.
Are PAIR block-off plates only for high-horsepower builds?
No. Any PAIR-equipped bike with an aftermarket exhaust or an ECU flash benefits from block-off plates. Street riders installing a slip-on or full system for sound and appearance often install block-off plates alongside just to eliminate the decel popping that comes with the exhaust change.
Need Help Choosing the Right PAIR Block-Off Plates?
Our team is here to help. Email us at sales@brocksperformance.com, click the chat button at the bottom of the screen, or browse the knowledge base under Support at the top of the page.