Description
Product Overview
The Kuryakyn 9930 breather filter is engineered specifically for Harley‑Davidson Evo Big Twin motorcycles produced between 1993 and 1999. This component replaces the factory breather system with a high‑quality assembly that utilizes chrome‑plated banjo elbows and precision‑machined tubing to direct crankcase gases upward, away from the engine interior. By encouraging oil droplets to settle before they can re‑enter the combustion chamber, the filter helps maintain a cleaner air‑fuel mixture and reduces the likelihood of oil‑related deposits on pistons and valves.
Crafted from durable, corrosion‑resistant materials, each element of the kit is designed to withstand the harsh vibration and temperature cycles typical of high‑performance motorcycles. The chrome finish not only adds a visual appeal but also provides an extra layer of protection against rust and wear, extending the service life of the breather system. The banjo fittings are sized to match the OEM ports, ensuring a seamless integration that does not require extensive modification of existing hardware.
Key specifications include a weight of approximately one pound, compact dimensions of 12 x 6 x 4 inches, and a painted exterior that blends with the original engine aesthetics. The kit comprises two chrome banjo elbow assemblies and a complete Bluegrass Breather hardware set, offering everything needed for a straightforward installation. Compatibility is confirmed for models equipped with Mikuni HSR series carburetors, making this a versatile upgrade for a broad segment of the Evo lineup.
![[Product front view showing all components]](https://www.assisttech.store/wp-content/uploads/2026/06/2b4757dae9bd43d09e703ddc510c4d6a.jpg)
In addition to the core functional benefits, the Kuryakyn breather filter contributes to overall engine health by reducing crankcase pressure fluctuations. By providing a reliable venting path, the system helps prevent oil seal wear and potential leaks that can arise from excessive pressure buildup. This engineering focus on both performance and durability reflects Kuryakyn’s commitment to delivering aftermarket solutions that meet or exceed original equipment standards.
The design also considers ease of maintenance. The chrome banjo elbows can be removed and inspected without special tools, allowing owners to verify the integrity of the venting pathway during routine service intervals. This accessibility supports long‑term reliability and simplifies troubleshooting for both professional technicians and DIY enthusiasts.
Usage
The Kuryakyn 9930 breather filter is ideal for riders who demand consistent performance from their Harley‑Davidson Evo motorcycles, whether on daily commutes, weekend rides, or track days. By ensuring that expelled oil vapors are efficiently routed away from the engine, the filter helps maintain optimal combustion conditions, which can translate into smoother throttle response and marginal improvements in fuel efficiency.
Installation is straightforward for anyone familiar with basic motorcycle maintenance. The kit includes detailed instructions that guide the user through removing the stock breather, attaching the chrome banjo elbows, and securing the hardware kit. The recommended installation procedure involves routing the vent line upward and out of sight beneath the fuel tank, allowing gravity to assist in oil droplet separation. This placement also keeps the vent line protected from debris and road spray.
For riders who frequently operate in dusty or high‑humidity environments, the breather filter offers added protection by minimizing the amount of oil mist that can be drawn back into the intake system. This is particularly beneficial for motorcycles used in off‑road conditions or in regions with significant seasonal temperature swings, where oil condensation can become a recurring issue.
The product is also suitable for performance‑oriented builds that incorporate aftermarket exhaust systems or high‑compression pistons. By maintaining a clean crankcase environment, the breather filter helps preserve the integrity of these upgrades, ensuring that the engine operates within its designed tolerances.
Why Choose Us
Choosing the Kuryakyn 9930 breather filter means selecting a component that has been rigorously tested for fit, function, and durability. Kuryakyn leverages decades of experience in the powersports aftermarket to develop products that address real‑world rider concerns. The company’s engineering team collaborates closely with motorcycle enthusiasts to refine designs that deliver measurable benefits without compromising the original aesthetic of the bike.
Quality assurance is a cornerstone of the manufacturing process. Each breather filter assembly undergoes multiple inspections, including dimensional checks, surface finish verification, and functional flow testing. This ensures that every unit leaving the factory meets strict performance criteria and provides consistent venting efficiency across the entire production run.
In addition to product excellence, Kuryakyn offers comprehensive customer support. Buyers receive access to a dedicated technical assistance line, detailed installation manuals, and online resources such as video tutorials and FAQs. Should any issue arise, the company’s warranty policy covers defects in material or workmanship, reinforcing confidence in the long‑term reliability of the breather filter.
The brand’s commitment to sustainability is reflected in the use of recyclable materials wherever possible, and the manufacturing facilities adhere to environmentally responsible practices. By choosing this product, riders not only enhance their motorcycle’s performance but also support a manufacturer that values ecological stewardship.
Key Features
- Chrome‑plated banjo elbows provide superior corrosion resistance and a sleek appearance that matches the bike’s original styling.
- Upward vent routing uses gravity to separate oil droplets, keeping the crankcase cleaner and reducing the risk of oil re‑circulation.
- Complete hardware kit includes all necessary fasteners, eliminating the need for additional purchases and simplifying installation.
- Designed for 1993‑1999 Harley‑Davidson Evo Big Twin models with Mikuni HSR carburetors, ensuring a direct fit without modifications.
- Dedicated after‑sales support and warranty coverage give owners peace of mind and access to expert assistance when needed.
FAQ
What makes the Kuryakyn breather filter different from the stock OEM part?
The Kuryakyn version replaces the standard rubber breather with chrome‑finished banjo elbows and precision‑cut tubing. This design improves the venting path, allowing oil droplets to settle out of the gas stream before they can re‑enter the engine, which the stock part does not actively manage.
Can I install the breather filter myself, or do I need a professional mechanic?
The kit is engineered for DIY installation. It comes with step‑by‑step instructions, and the required tools are limited to standard socket and wrench sets. However, if you are uncomfortable working on the engine’s vent system, a qualified motorcycle technician can complete the installation quickly.
Will the breather filter affect my bike’s emissions compliance?
The filter is designed to vent crankcase gases to the atmosphere in a controlled manner, similar to the original system. It does not alter the exhaust flow or catalytic converter operation, so it should not impact emissions testing results. Always verify local regulations if you have specific compliance concerns.
How often should I inspect or replace the breather filter?
Routine inspection is recommended during regular service intervals, typically every 5,000 miles. Look for signs of blockage, corrosion, or damage to the banjo elbows. In most cases the filter will last the lifetime of the motorcycle, but replacement may be necessary if severe wear is observed.
Is the kit compatible with other Harley‑Davidson models beyond the Evo Big Twin?
The 9930 model is specifically engineered for the Evo Big Twin platform with Mikuni HSR carburetors. While some components may physically fit other Harley‑Davidson bikes, we advise using the part only on the listed compatible models to ensure optimal performance and safety.






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