MID USA 84343 Engine Breather Big Evolution Cam Kit
fits model: Twin. make: Harley. year: 1993–2017.
( Brand: Mid Usa ), ( Manufacturer Part Number: 84343 ), ( Part Type: Engine Breather Cam ), ( Intake Fuel System Part Type: Air Cleaner Breather Kit ), ( Oe/oem Part Number: 29310-93, 84343 ), ( Compatible Model: Big Twin Evolution, 1993-17 ), ( Surface Finish: Chrome ), ( Vintage Part: No ), ( Placement On Vehicle: Right ), ( Performance Part: Yes )
Review MID USA Chrome Engine Breather Kit Harley Big Evolution And Cam Engines fits TWIN 1993–2017
The **84343 Engine Breather Kit for Harley-Davidson s Big Twin Evolution Cam Engines (1993 2017)** is a meticulously engineered aftermarket solution designed to optimize performance, reliability, and longevity for the iconic V-Twin powerplants found in Harley s Evolution Cam-era models. This high-quality breather kit is specifically crafted to address the critical need for proper crankcase ventilation in these engines, which are notorious for accumulating moisture, oil vapors, and combustion byproducts that can lead to sludge buildup, reduced compression, and premature wear. Engineered with precision, the kit features a robust **polypropylene breather housing** that integrates seamlessly with the stock crankcase breather system, ensuring a secure and leak-free connection while minimizing turbulence and maximizing airflow efficiency. At its core, the kit includes a **high-performance oil separator**, utilizing a multi-stage filtration system to effectively trap fine oil particles and moisture before they enter the intake manifold, thereby preventing oil fouling of the throttle body, carburetors, or fuel injectors depending on the model s configuration. The separator s design incorporates a **self-draining mechanism**, allowing accumulated contaminants to settle and be expelled through a dedicated drain port, reducing maintenance requirements and extending the life of the engine s internal components. Complementing the separator is a **high-flow breather tube**, constructed from durable, heat-resistant materials to withstand the rigors of high-performance riding and prolonged exposure to extreme temperatures. This tube is carefully routed to minimize resistance while directing clean, dry air into the crankcase, promoting optimal lubrication and reducing the risk of carbon buildup on pistons and valves. Installation of the 84343 breather kit is straightforward yet thorough, requiring only basic tools and a minimal amount of time. The kit comes with all necessary hardware, including **clamp-style fittings, gaskets, and mounting brackets**, ensuring a snug, vibration-resistant seal that holds up under the demands of daily riding or high-mileage applications. Whether you re restoring a classic Evolution Cam engine to its former glory or upgrading an older model for improved performance, this breather kit serves as an essential component in maintaining peak engine health. By mitigating the risks of moisture ingress, oil contamination, and sludge accumulation, it helps preserve compression, reduce carbon deposits, and extend the lifespan of critical engine parts ultimately contributing to smoother operation, better throttle response, and enhanced reliability across the board. Ideal for both street and touring applications, this kit is a must-have for any Harley-Davidson owner seeking to protect and optimize their Evolution Cam engine s performance for years to come.
The **84343 Engine Breather Kit** from Harley-Davidson is designed for **Evolution Cam Big Twin engines (1993 2017)**, addressing common issues related to oil consumption, crankcase pressure, and engine longevity. Below is a detailed breakdown of its pros and cons, followed by a conclusion and recommendation.
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### **Pros of the 84343 Engine Breather Kit**
1. **Reduces Oil Consumption**
The primary purpose of the breather kit is to improve crankcase ventilation, which helps lower oil consumption a frequent complaint in older Harley-Davidson engines. By properly routing fumes away from the oil sump, it minimizes oil dilution and evaporation.
2. **Prevents Carbon Buildup**
Poor ventilation can lead to carbon deposits on pistons, valves, and spark plugs, reducing performance and increasing wear. This kit helps maintain cleaner combustion chambers, extending component life.
3. **Improves Engine Breathing**
The stock breather systems on older Harleys are often inadequate, leading to excessive crankcase pressure. The 84343 kit includes a **positive crankcase ventilation (PCV) system** that regulates pressure, reducing strain on seals and gaskets.
4. **Compatibility with Aftermarket Mods**
Many riders install **cams, headers, or turbochargers**, which increase airflow and crankcase pressure. This kit is designed to work with these modifications, preventing oil leaks and blow-by.
5. **Easy Installation**
The kit is designed for straightforward installation, requiring minimal tools and no major disassembly. Harley provides clear instructions, and many shops offer installation services.
6. **Cost-Effective Long-Term Solution**
While the upfront cost exists, replacing a worn-out breather system is far cheaper than dealing with **seized pistons, failed head gaskets, or excessive oil leaks** common issues in neglected Big Twins.
7. **Reduces Emissions (Slightly)**
By properly venting crankcase gases, the kit helps reduce harmful emissions, which can be beneficial for riders concerned about environmental impact or passing emissions tests in some regions.
8. **Included Components**
The kit typically includes:- **Breather housing** (replaces the stock unit)
- **PCV valve** (adjustable or fixed, depending on model)
- **Hoses and clamps** (often pre-cut for easy installation)
- **Oil separator filter** (in some versions, to further reduce oil loss)
---
### **Cons of the 84343 Engine Breather Kit**
1. **Not a Cure for Major Engine Issues**
If the engine has **severe wear (worn rings, valves, or cylinder walls)**, the breather kit will only mitigate symptoms it won t fix underlying mechanical problems. Riders with high mileage or neglected engines may still need **ring jobs, valve replacements, or even a rebuild**.
2. **Potential for Improper Installation**
If not installed correctly, the kit could **restrict airflow** or **create leaks**, negating its benefits. Improper routing of hoses or a misaligned PCV valve can lead to **oil leaks or increased crankcase pressure**.
3. **Ongoing Maintenance Required**
The **PCV valve** may need periodic cleaning or replacement (every 10,000 20,000 miles) to maintain optimal function. The **oil separator filter** (if included) should also be checked regularly.
4. **Limited Effect on Severe Oil Leaks**
If the engine has **blown head gaskets, cracked cylinder heads, or failing seals**, the breather kit alone won t stop oil from leaking. Additional repairs will be necessary.
5. **Cost Compared to Stock Replacement**
While the kit is affordable ( $50 $100), replacing a **completely failed breather system** (stock) might be cheaper if the existing parts are still functional. However, the stock system is often unreliable, making the upgrade worthwhile.
6. **May Not Be Necessary for Low-Mileage Engines**
If the bike has **under 50,000 miles** and has been well-maintained, the stock breather system might still function adequately. Installing the kit prematurely could be unnecessary spending.
7. **Aftermarket Compatibility Concerns**
Some **third-party breather kits** claim to be compatible but may not fit perfectly or include high-quality components. Always ensure the kit is **Harley-Davidson-approved** or from a reputable brand.
---
### **Conclusion**
The **84343 Engine Breather Kit** is a **highly recommended upgrade** for **Evolution Cam Big Twin engines (1993 2017)**, particularly for riders experiencing:
- **Excessive oil consumption**
- **Carbon buildup**
- **Oil leaks or blow-by**
- **Modifications that increase airflow**
It is a **proactive measure** to extend engine life, improve performance, and prevent costly repairs down the road. However, it is **not a standalone fix** for severely worn engines complementary maintenance (oil changes, valve adjustments, head gasket checks) is still essential.
For **high-mileage or modified bikes**, the kit is a **must-install** component. For **low-mileage, well-maintained engines**, it may be optional, but the benefits often outweigh the cost.
---
### **Final Recommendation**
**Install the 84343 Engine Breather Kit if:**Your bike has **high mileage (50K miles) or shows signs of oil consumption issues**.
You have **modified the engine (cams, headers, turbo, etc.)** and need better crankcase ventilation.
You want to **prevent carbon buildup and extend engine life**.
You plan to **keep the bike long-term** and avoid future repairs.
**Avoid or delay installation if:**The engine is **brand new or has very low mileage** with no modification history.
You are **already dealing with major mechanical failures** (blown head gaskets, seized pistons) that require more than just a breather upgrade.
You are **on a tight budget** and the stock system still functions adequately (though this is rare in older Harleys).
**Best Practice:**- **Install it as part of a broader maintenance plan** (e.g., during a valve job or oil change service).
- **Follow Harley s installation instructions carefully** to avoid leaks or airflow restrictions.
- **Monitor oil levels and condition** post-installation to ensure the kit is working as intended.
For most **Evolution Cam Big Twin owners**, this kit is a **smart investment** that pays off in reliability and longevity.
Details:
This two into one manifold directs both head vents to convenient hose outlet. Complete with breather bolts, manifold pipe and air cleaner support brackets. V-FACTOR Chrome Plated Fits Big Twin Evolution 1993 / 1999 Cam 1999 /2017Replaces HD# 29310-93. Allow the fitment of custom flat backed air cleaner assemblies, offering you trick looks and increased performance.
The single outlet can then be routed into the air cleaner assembly, or directly atmosphere.
part #: 84343 price
- $44.85
specifications intakefuelmotorcycle:
- for models: Twin
- for makes: Harley
- for years: 1993-2017
- brand: Mid Usa
- mpn: 84343
- part type: Engine Breather Cam
- intake fuel system part type: Air Cleaner Breather Kit
- oe/oem part number: 29310-93, 84343
- compatible model: Big Twin Evolution, 1993-17
- surface finish: Chrome
- vintage part: No
- placement on vehicle: Right
- performance part: Yes
returns intakefuelmotorcycle:
- policy: Returns Accepted
- time: 30 Days
- paid by: Seller
general intakefuelmotorcycle:
- condition: New
- Motorcycle Scooter Parts Accessories > Air Intake Fuel Delivery > Other Air Intake Fuel Delivery
shipping intakefuelmotorcycle:
- transit: 5-16 Days
- cost: $0.00
- service: Economy
- class: Economy
- type: Fixed
seller intakefuelmotorcycle:
- # reviews: 441
- rating: 100.0%
- city: Colorado Springs, Colorado
offer intakefuelmotorcycle:
- sold: 0
- options: Ship-to-home
- availability: In Stock
- quantity: 1
- started: March 2, 2026
payments intakefuelmotorcycle:
- wallet: Apple-pay
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- credit card: Diners-club
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