For enthusiasts of the Aprilia SR 50 and other performance machines, the master cylinder is a cornerstone of both power and control. Upgrading this critical component can significantly impact your ride’s responsiveness, power output, and overall reliability. Whether you’re building a high-output two-stroke engine or seeking superior braking performance, the right master cylinder kit is essential for a tuned machine.
This roundup focuses on components designed for performance and longevity, from big bore cylinder kits that boost horsepower to precision-engineered clutch and brake master cylinders that enhance control. We’ve compiled a list of top-tier options to help you make an informed decision for your next upgrade, ensuring your vehicle performs at its peak for miles to come.
The Best AP Racing Master Cylinders and Engine Upgrades
- Ap SR 50 Cylinder Kit for Fun Master Racing Sport LC
- Scooter 70cc 47mm Big Bore Cylinder Head For Ap-ril-ia SR 50
- 50cc 70cc Cylinder Gasket Set for Ap SR 50 Racing Sport LC
- Crankshaft connecting rod for AP-RIL-IA SR 50 Fun Master
- Ap SR 50 70cc Big Bore Cylinder Kit for Fun Master
- All Balls Racing 18-4023 Clutch Master Cylinder Kit
- AP Racing by Alcon CP7846-1004C Brake Master Cylinder
- AP Racing CP7855-1004C Competition Master Cylinder
Ap SR 50 Cylinder Kit for Fun Master Racing Sport LC
This cylinder kit is engineered to significantly improve your engine’s performance. The increased cylinder volume directly translates to a higher power output, giving your scooter a noticeable boost in acceleration and top speed. It’s a direct upgrade for riders seeking more vigorous performance from their 2-stroke engine.
Durability is a key feature, with a highly wear-resistant design that stands up to high operating temperatures. This resistance to heat reduces overall wear, contributing to a longer service life. Precision manufacturing further ensures excellent sealing and improved engine stability, making this a reliable component for your build.
Scooter 70cc 47mm Big Bore Cylinder Head
Designed for the Aprilia SR 50, this 70cc big bore cylinder head is a straightforward upgrade to increase displacement and power. While the manufacturer notes it is easy to install, they recommend professional operation to ensure optimal performance and fitment, safeguarding your engine’s integrity.
The product is built with quality manufacturing to provide maximum durability and resist damage under stress. This focus on robust construction promises good performance and a long service life. For added peace of mind, each unit is tested before shipping to confirm it meets functional standards.
50cc 70cc Cylinder Gasket Set for Ap SR 50
This cylinder gasket set is a vital component for any engine rebuild or upgrade. Its primary function is to provide a perfect seal between engine components, preventing leaks of coolant, oil, or compression. This is fundamental for ensuring proper and efficient engine operation after modifications.
Constructed to adapt to high-temperature environments, these gaskets prevent damage that can occur from extreme heat, thereby extending the service life of your engine assembly. They also offer effective protection against moisture and corrosion, which further contributes to the longevity and reliability of your engine.
Crankshaft connecting rod for AP-RIL-IA SR 50
This crankshaft connecting rod is a critical internal engine part for the Aprilia SR 50. It is designed for a straightforward installation process, though the complexity of engine work means it is best handled by a professional mechanic to ensure precise alignment and balance.
The manufacturing process prioritizes maximum durability, creating a component that is not easy to damage under the high-stress conditions of a performance engine. This results in good performance characteristics and a long service life. Each connecting rod is tested before shipping to verify its quality and integrity.
Ap SR 50 70cc Big Bore Cylinder Kit
This 70cc big bore cylinder kit is another excellent option for upgrading your Aprilia SR 50. The increased cylinder volume is a proven method for boosting power output, providing a significant performance gain for your 2-stroke scooter, making it ideal for racing or spirited riding.
The kit features a highly wear-resistant design that can withstand high temperatures, which reduces wear and contributes to a longer overall lifespan. Precision manufacturing is a hallmark of this product, ensuring excellent sealing between components and improved stability for the entire engine assembly.
All Balls Racing Clutch Master Cylinder Kit
This comprehensive clutch master cylinder kit from All Balls Racing is designed to troubleshoot and resolve leaking master cylinders. The kit includes a replacement hard-anodized aluminum piston, cover screws, boot, and spring, providing all the necessary components for a complete rebuild.
It offers broad compatibility with a range of Honda Gold Wing models and several Yamaha sport bikes and cruisers. The brand supports its product with a 1-year warranty, demonstrating confidence in its performance and durability, and promising support should any issues arise after installation.
AP Racing by Alcon CP7846-1004C Brake Master Cylinder
For the serious motorsports enthusiast, the AP Racing by Alcon brake master cylinder represents the pinnacle of braking control. This component is engineered for high-performance applications where consistent pedal feel and reliable hydraulic pressure are non-negotiable.
Constructed to the highest standards, this master cylinder is built for longevity under extreme conditions, such as on the track or in competitive rallying. Its design focuses on providing the driver with precise modulation and stopping power, which is critical for both performance and safety.
AP Racing CP7855-1004C Competition Master Cylinder
The AP Racing CP7855-1004C is a competition-grade master cylinder built for demanding environments. It is the choice for professional racing teams and advanced amateur drivers who require absolute reliability and peak performance from their vehicle’s control systems.
This model is synonymous with durability, featuring materials and construction techniques that resist the fatigue and failure common in lesser components. Its precision engineering ensures immediate response and consistent performance lap after lap, making it a long-term investment for any serious performance build.
Buying Guide: How to Choose the Best AP Racing Master Cylinder
When I’m looking to upgrade my braking system, the master cylinder is a component I never overlook. It’s the heart of the hydraulic system, and getting the right one makes all the difference in pedal feel and overall performance. AP Racing is a name I trust, but with so many options, choosing the best AP Racing master for performance and longevity requires a bit of know-how. Here’s what I always consider before making a purchase.
First, I think about the bore size. This is probably the most critical factor. A larger bore moves more fluid per inch of pedal travel, which can give you a firmer pedal. That sounds great, right? But there’s a trade-off. A bore that’s too large for your setup can make the pedal feel wooden and require a lot more leg effort. Conversely, a smaller bore gives you a longer, more progressive pedal stroke with less effort, which can be fantastic for modulation. I match the bore size to my caliper piston area and the type of driving I do. Track cars often benefit from a larger bore, while a street-driven car might be better with a smaller one.
Next, I check the reservoir type and capacity. Remote reservoirs are common on race-oriented models and are great for dealing with high fluid temperatures and preventing aeration. They also make bleeding the system easier. For a dedicated track car, this is a must. For a street car that sees occasional hard use, a master cylinder with an integrated reservoir might be simpler and cleaner. I also make sure the reservoir has enough capacity for my specific caliper setup, especially if I’m running large pistons front and rear.
Material and construction are huge for longevity. AP Racing masters are typically made from hard-anodized aluminum, which is lightweight and resistant to corrosion. I look for high-quality seals that can handle high-temperature racing brake fluid without degrading over time. The finish on the unit is also a good indicator of quality; a well-machined, smoothly finished body suggests precision manufacturing that will stand up to vibration and heat cycling.
Finally, I consider the mounting and pushrod attachment. It has to fit my car’s specific pedal box without needing major fabrication. The pushrod length and clevis type need to match my pedal for proper geometry and to avoid binding. Getting this wrong can lead to poor pedal feel or even the master cylinder not fully releasing, which is a safety hazard. I always double-check the technical drawings and specifications to ensure a perfect fit. Taking the time to get these details right is what separates a good upgrade from a great one that delivers both immediate performance and long-term reliability.
FAQ
What is the difference between a standard and a radial master cylinder?
The main difference comes down to design and mounting. A standard master cylinder typically has a long body that mounts through holes in the firewall or pedal box. A radial master cylinder is a more modern, compact design that mounts perpendicular to the pedal, often using a bracket. Radial masters are generally lighter, stiffer, and reduce flex under high loads, which translates to a more consistent pedal feel. They are the go-to for most serious race applications. For a street car, a well-chosen standard master cylinder can work perfectly well, but if you’re chasing the ultimate pedal response, a radial is the way to go.
How often should I rebuild my AP Racing master cylinder?
There’s no single answer, as it depends entirely on usage. For a full-season race car, I’d consider a rebuild an annual maintenance item. The constant high pressures and temperatures wear out seals. For a spirited street car or a weekend track toy, you can go much longer—maybe every two to three years, or whenever you notice a change in pedal feel, like it becoming spongy or traveling closer to the floor. The key is to use high-quality brake fluid and change it regularly, as contaminated fluid is a primary cause of seal deterioration. Inspecting for any external fluid leaks is also a good practice.
Can I mix an AP Racing master cylinder with my existing brake calipers?
You can, but you need to be very careful. The master cylinder and calipers work as a hydraulic system, so their sizes need to be compatible. If you install a master cylinder with a bore that’s too large or too small for your caliper’s total piston area, the pedal feel will be off. It might be too hard or too long. I always recommend doing the math or consulting with a specialist to calculate the correct bore size for your specific front and rear caliper setup to ensure you get the best AP Racing master for performance and longevity with your components.
Why is my pedal feeling soft after installing a new master cylinder?
A soft pedal after a new install almost always points to air in the system. These high-performance units can be tricky to bleed completely. I start by making sure I’m using the correct bleeding sequence for my car (often starting with the caliper farthest from the master). A pressure bleeder is my best friend for this job. If bleeding doesn’t fix it, I check for any leaks at the fittings. Another, less common possibility is that the master cylinder bore is too large for the calipers, resulting in insufficient fluid displacement to fully pressurize the system quickly.
Are AP Racing master cylinders only for track cars?
Not at all. While their heritage is in motorsport, the benefits translate directly to high-performance street cars. The improved pedal feel, consistency, and build quality are noticeable upgrades over many OEM units, especially if you’ve upgraded your calipers and rotors. For anyone who drives their car hard on a canyon road or plans to do a track day, an AP Racing master cylinder is a fantastic upgrade that improves control and driver confidence. You’re investing in a component that is over-built for street use, which guarantees exceptional longevity.