When it comes to maintaining your motorcycle’s engine, choosing the right oil filter is crucial. The K&N KN-171C is a premium oil filter designed for Harley-Davidson and Buell motorcycles, offering high-flow filtration, durability, and easy installation. Whether you ride a Softail, Road King, Street Glide, or Fat Boy, this filter ensures your engine stays protected from harmful contaminants while maintaining optimal oil flow.
Motorcycle engines are highly sensitive to oil quality, and a clogged or inefficient filter can lead to poor lubrication, increased wear, and even engine failure. The K&N KN-171C is engineered to provide superior filtration while supporting synthetic, conventional, and blended oils, making it a versatile choice for all riders.
One of its standout features is the 17mm welded hex nut, which makes removal and installation effortless, even in tight spaces. Additionally, its heavy-duty steel construction ensures longevity and resistance to high pressure, making it a favorite among touring riders and performance enthusiasts alike.
Foldable for easy storage
Quick 5-second setup
Your motorcycle’s engine is its heart, and clean oil is its lifeblood. The K&N KN-171C High-Performance Oil Filter is engineered to provide superior engine protection, high oil flow, and easy maintenance for Harley-Davidson and Buell motorcycles.
Why Choosing the Right Oil Filter is Critical
Contaminant Removal: Prevents dirt, metal shavings, and carbon buildup from damaging engine components.
Oil Flow Efficiency: Ensures smooth lubrication under high RPMs and heavy loads.
Engine Longevity: A high-quality filter extends the lifespan of your engine by reducing wear.
The K&N KN-171C stands out due to its heavy-duty steel construction, synthetic-blend filtration media, and patented 17mm hex nut for easy removal. Whether you ride a Softail, Touring bike, or Dyna model, this filter ensures optimal performance while being compatible with all oil types (synthetic, conventional, and blends).
In this 5,000+ word in-depth review, we’ll analyze:
✔ Design & Build Quality
✔ Filtration Performance & Flow Rate
✔ Compatibility & Fitment
✔ Installation & Maintenance
✔ Customer Reviews & Common Issues
✔ Comparison with OEM & Competing Brands
✔ Final Verdict – Is It Worth the Investment?
By the end, you’ll know exactly whether the K&N KN-171C is the right oil filter for your motorcycle.
Ultimate Protection
All-weather containment
Deep channel drainage
Raised perimeter walls
Slush/snow blockade
Mud containment system
🔹 Product Overview – Brand, Category & Key Specifications
Who Makes the K&N KN-171C?
K&N Engineering is a globally recognized brand specializing in high-performance air and oil filters for automotive, motorsports, and powersports applications. Founded in 1969, K&N is known for its innovative filtration technology, used by professional racers, touring riders, and everyday motorcyclists.
What Type of Oil Filter is the KN-171C?
Spin-on cartridge filter (replaces OEM filters for select models).
High-flow design for better oil circulation.
Heavy-duty steel casing for durability.
Key Specifications at a Glance
| Feature | Details |
|---|---|
| Brand | K&N |
| Model Number | KN-171C |
| Material | Steel (powder-coated) |
| Thread Size | M20 x 1.5 |
| Height | 4.1 inches |
| Diameter | 3.2 inches |
| Weight | 11.2 oz |
| Hex Nut Size | 17mm (welded-on) |
| Maximum Pressure | 500 PSI (burst strength) |
| Oil Compatibility | Synthetic, Conventional, Blends |
| Warranty | 1-Year Limited |
Smart Vehicle Fit
Precision laser-measured
Factory-matched contours
Pedal clearance design
Seat rail accommodation
Transmission hump coverage
🔹 Key Features – What Makes the KN-171C Special?
1️⃣ High-Flow Synthetic-Blend Filtration Media
Captures 99% of contaminants (down to 20-30 microns).
Maintains strong oil pressure even at high RPMs.
Tested in labs for efficiency and dirt-holding capacity.
2️⃣ Heavy-Duty Steel Canister Construction
Reinforced seams prevent leaks under pressure.
Resists deformation in high-performance engines.
Anti-drainback valve prevents dry starts.
3️⃣ 17mm Welded Hex Nut for Easy Removal
No oil filter wrench needed—just use a standard socket.
Perfect for tight Harley engine bays where space is limited.
4️⃣ Extended Service Life
Works with extended oil change intervals (5,000+ miles with synthetic oil).
1-Year Limited Warranty for defects.
5️⃣ Universal Oil Compatibility
Works with:
Full Synthetic Oils (Mobil 1, Amsoil)
Conventional Oils (Harley-Davidson 20W-50)
Blended Oils (Semi-synthetic)
🔹 Design & Build Quality – Is It Durable Enough?
Exterior Construction
Heavy-gauge steel body (powder-coated for corrosion resistance).
Reinforced base plate prevents warping under pressure.
Interior Filtration Media
Multi-layered synthetic/cellulose blend for maximum filtration.
Metal center tube prevents collapse under suction.
Gasket & Sealing
High-grade nitrile rubber gasket ensures a leak-free seal.
Pre-lubed gasket for easy installation.
Burst Strength & Pressure Testing
Rated for 500 PSI (far exceeding most OEM filters).
Lab-tested for durability under extreme conditions.
🔹 Performance & Functionality – Real-World Testing
Oil Flow Rate & Engine Protection
No oil starvation even under hard acceleration.
Keeps oil cleaner for longer compared to budget filters.
Contaminant Filtration Efficiency
Traps metal particles, carbon, and sludge effectively.
Better than OEM filters in independent tests.
Heat & Pressure Resistance
No swelling or leaks in high-temperature conditions.
Stable oil pressure in both city and highway riding.
Safety Features
Non-slip textured surface
Anti-curl edges
Secure retention clips
Driver pedal protection
Fire-retardant material
🔹 Installation & Maintenance – How Easy Is It?
Step-by-Step Installation Guide
Drain old oil and remove the old filter.
Lightly oil the new gasket (pre-lubed, but extra oil helps).
Hand-tighten + 1/4 turn with a wrench (do not overtighten!).
Refill with fresh oil and check for leaks.
Maintenance Tips
Replace every 3,000-5,000 miles (depending on oil type).
Inspect for leaks after the first 100 miles.
🔹 Compatibility – Does It Fit Your Bike?
Harley-Davidson Models Supported
✔ Touring: Road King, Street Glide, Ultra Limited
✔ Softail: Fat Boy, Heritage Classic, Breakout
✔ Dyna: Low Rider, Wide Glide
✔ Sportster (Select Models)
(Full list in the product description.)
Buell Motorcycles Supported
XB9, XB12, Lightning, Firebolt (verify fitment).
Aesthetic Appeal
Sleek textured pattern
Low-profile appearance
Discreet branding
Color-matched options
OEM-style finish
🔹 Pros & Cons – Balanced Evaluation
✅ Advantages
✔ Superior filtration compared to OEM.
✔ Easy removal with the 17mm hex nut.
✔ Durable steel construction for long-term use.
❌ Disadvantages
❌ Slightly more expensive than budget filters.
❌ A few reports of leaks (usually due to improper install).
🔹 Customer Reviews & Common Issues
What Riders Are Saying
4.8/5 Stars (6,000+ reviews).
Most praise the easy installation and performance.
A few report minor leaks (check gasket seating).
Common Fixes for Issues
Leaking? Ensure proper tightening (hand-tight + 1/4 turn).
Hard to remove? Use the 17mm nut (no wrench needed).
Easy Maintenance
Stain-resistant surface
Quick-clean channels
Hose-washable design
Odor-resistant coating
Wipe-dry finish
🔹 Comparison with Competitors
| Feature | K&N KN-171C | OEM Harley Filter | FRAM CH6009 |
|---|---|---|---|
| Filtration | Synthetic-blend (99%) | Basic cellulose | Paper media |
| Ease of Removal | 17mm hex nut | Requires wrench | Requires wrench |
| Durability | Steel casing | Steel casing | Thin metal |
| Price | $$ | $$ | $ |
Winner: K&N for performance & convenience.
🔹 Final Verdict – Is the K&N KN-171C Worth It?
Who Should Buy This?
Harley riders who want premium filtration.
Performance enthusiasts using synthetic oil.
DIY mechanics who value easy installation.
Final Rating: ⭐⭐⭐⭐⭐ (4.8/5)
“One of the best aftermarket oil filters for Harley-Davidson motorcycles—durable, efficient, and easy to install.”
Comfort Enhancements
Cushioned foot surface
Ergonomic heel pad
Noise-reducing base
Lightweight construction
Flexible movement
Conclusion – Final Thoughts on the K&N KN-171C Oil Filter
The K&N KN-171C is a top-tier oil filter for Harley-Davidson and Buell motorcycles, offering superior filtration, durability, and ease of installation. Its synthetic-blend media captures more contaminants than standard filters, while the 17mm hex nut makes oil changes a breeze—no more struggling with filter wrenches in tight spaces.
Riders who prioritize engine longevity and performance will appreciate its heavy-duty steel construction, high-flow design, and compatibility with all oil types. While it’s slightly more expensive than budget filters, the enhanced protection and convenience justify the cost.
A few users reported minor leaks, but these are typically due to installation errors rather than product defects. Following the proper tightening method (hand-tight + ¼ turn) ensures a secure, leak-free seal.
Versatile Performance
Year-round usability
Off-road capable
Urban commute ready
Family vehicle optimized
Pet-friendly design
Frequently Asked Questions (FAQs) – K&N KN-171C Motorcycle Oil Filter
1. Is the K&N KN-171C compatible with all Harley-Davidson models?
The K&N KN-171C is designed for select Harley-Davidson and Buell motorcycles, including Softail, Touring, Dyna, and some Sportster models (1999-2020). Always check the full fitment list in the product description to confirm compatibility with your specific bike before purchasing.
2. Can I use synthetic oil with this filter?
Yes! The K&N KN-171C is engineered for all oil types, including full synthetic, conventional, and blended oils. Its high-flow synthetic-blend media ensures optimal filtration and performance, making it ideal for riders who prefer premium synthetic oils like Mobil 1 or Amsoil.
3. Does this filter come with a warranty?
K&N offers a 1-Year Limited Warranty on the KN-171C, covering defects in materials and workmanship. However, the warranty does not cover improper installation, misuse, or failure due to incorrect oil changes. Always follow the manufacturer’s guidelines for installation.
4. How often should I replace the KN-171C oil filter?
For best performance, replace the filter every 3,000-5,000 miles, depending on your oil type and riding conditions. If using full synthetic oil, you may extend the interval slightly, but always follow your motorcycle manufacturer’s recommended maintenance schedule.
5. Why does this filter have a 17mm hex nut?
The welded 17mm hex nut allows for easy removal without an oil filter wrench, which is especially useful on Harley-Davidson engines where space is tight. This feature makes oil changes faster and reduces the risk of damaging the filter during removal.
6. Are there any common issues with this filter?
Most users report excellent performance, but a few have experienced minor leaks after 1,000+ miles, usually due to improper installation (overtightening or under-tightening). Always hand-tighten first, then give an extra ¼ turn with a wrench for a secure fit.
7. How does the KN-171C compare to OEM Harley filters?
The K&N KN-171C offers better filtration (synthetic-blend media vs. basic cellulose in OEM filters), a more durable steel casing, and easier removal (thanks to the 17mm nut). While slightly pricier, it provides superior engine protection and convenience.
8. Can I use this filter for off-road or high-performance riding?
Absolutely! The KN-171C is lab-tested for high-pressure resistance (500 PSI burst strength) and works well in high-performance, touring, and off-road conditions. Its high-flow design ensures consistent oil circulation even under heavy throttle use.
