HARLEY-DAVIDSON 18400073-18400073B Engine Solenoid Auto Compression Release

( Brand: Harley-davidson ), ( Manufacturer Part Number: 18400073;18400073B ), ( Type: Exhaust Valve ), ( Country Of Origin: United States )

Review HARLEY DAVIDSON 18400073 Engine Solenoid Auto Compression Release fits M8 2019–2025

The **Harley-Davidson 18400073 / 18400073B 2019-2025 M8 Engine Solenoid (Auto Compression Release)** is a precision-engineered component designed exclusively for Harley-Davidson s high-performance **M8 Sportster** and **M8 Ultra** models, ensuring seamless operation of the engine s compression release mechanism. This solenoid serves as a critical interface between the rider s compression release lever and the engine s valve train, allowing for effortless cranking of the engine when starting in cold conditions or after prolonged inactivity. Crafted from durable materials, including high-grade metal alloys and corrosion-resistant coatings, the solenoid is built to withstand the demanding environments of motorcycle use, from dusty backroads to wet urban commutes. Its **auto-compression release** feature eliminates the need for manual adjustment, providing a smooth, consistent engagement with the engine s valve springs, which reduces wear on both the solenoid and the valve train over time. The design incorporates a **sealed internal mechanism** to prevent contamination from road debris, oil, or moisture, ensuring long-term reliability and performance. Whether installed during routine maintenance or as part of a performance upgrade, this solenoid maintains the M8 s legendary smoothness and responsiveness, making it an essential part of any serious rider s maintenance regimen. Its compatibility with the **2019 through 2025 model years** ensures a perfect fit for the latest iterations of Harley-Davidson s flagship Sportster line, delivering the precision and durability riders expect from the brand.

### **Pros and Cons of Buying a Harley-Davidson M8 Engine with Auto Compression Release (2019 2025 Models, Part Numbers 18400073/18400073B)**

#### **Pros**

1. **Performance and Power**

The M8 engine is a high-performance inline-four cylinder design, offering significantly more power than Harley s traditional V-twin engines. It produces around **110 120 hp** (depending on the model year and configuration), which provides a sportier, more responsive ride compared to traditional Harley-Davidsons. This makes it ideal for those seeking a more aggressive, high-revving experience.

2. **Modern Technology and Efficiency**

Unlike older Harley engines, the M8 features **direct fuel injection**, **variable valve timing**, and **turbocharging** (in some models), which improves fuel efficiency and reduces emissions. The auto compression release (ACR) feature simplifies starting in cold weather by reducing engine compression, making it easier to crank over.

3. **Smoother and More Refined Ride**

The inline-four layout produces less vibration compared to a V-twin, resulting in a quieter, more refined ride. This is particularly noticeable at highway speeds, where the engine runs more smoothly without the traditional Harley "thump."

4. **Compatibility with Harley s EvoTech Platform**

The M8 engine is part of Harley s **EvoTech** lineup, which integrates modern electronics, including **Harley s Ride Mode Control (RMC)**. This allows riders to adjust throttle response, traction control, and other settings via the handlebar-mounted controls, offering a more customizable experience.

5. **Potential for Future-Proofing**

Harley has indicated that the M8 engine will likely remain in production for several years, meaning parts and support will be available longer than some older Harley engines. This could make it a more reliable long-term investment compared to discontinued models.

6. **Attractive to a Broader Audience**

The M8 s performance-oriented nature appeals to riders who want a Harley with more power and modernity. It also attracts younger or more performance-focused buyers who may have previously avoided Harley due to its traditional image.

---

#### **Cons**

1. **Higher Cost and Maintenance Expenses**

The M8 engine is significantly more expensive than Harley s traditional V-twin engines. Prices for bikes equipped with it (such as the **Pan America, LiveWire, or Sportster 1200**) are higher, and repairs or replacements for M8 components (e.g., turbochargers, fuel injectors, or ACR solenoids) can be costly. Harley s dealership labor rates are also among the highest in the industry.

2. **Complexity and Reliability Concerns**

The M8 engine is more complex than Harley s traditional V-twins, with additional components like turbochargers, fuel injection systems, and advanced electronics. While Harley has improved reliability with this engine, some early models (especially in the **Pan America**) experienced issues with **turbo lag, fuel system failures, and electrical gremlins**. Later models (2021 2025) have seen refinements, but the risk of expensive repairs remains higher than with a V-twin.

3. **Lack of Traditional Harley Character**

Many Harley purists argue that the M8 lacks the **raw, unfiltered sound and feel** of a V-twin engine. The inline-four produces a more refined, almost "car-like" noise, which may disappoint riders who value the classic Harley growl. Additionally, the power delivery is more linear and less "peppy" at low RPMs compared to a V-twin.

4. **Limited Aftermarket Support**

While the M8 engine is supported by Harley, aftermarket parts (e.g., exhaust systems, ECU tuning, or performance upgrades) are not as widely available or tested as they are for V-twin Harleys. This can make modifications more difficult and expensive.

5. **Potential for Early Wear Issues**

Some early M8-equipped models (particularly the **2019 2020 Pan America**) reported problems with **turbocharger failures, fuel pump issues, and ACR solenoid malfunctions**. While Harley has addressed many of these through recalls and software updates, early adopters may have faced unexpected repair costs.

6. **Resale Value Uncertainty**

The M8 engine is relatively new, and its long-term resale value is still uncertain. While Harley s EvoTech platform is likely to remain relevant, the market for these bikes may not hold value as strongly as traditional Harley models, especially if buyer interest in performance-oriented Harleys declines.

---

### **Conclusion**

The **Harley-Davidson M8 engine (2019 2025, with auto compression release)** is a **bold step forward** for Harley-Davidson, offering modern performance, efficiency, and technology. It is ideal for riders who:

- Want a **more powerful, refined, and tech-savvy** Harley experience.

- Prefer **smoother power delivery** and **better fuel economy** than a V-twin.

- Are willing to **invest in a higher-priced, more complex bike** with potential for higher maintenance costs.

- Enjoy **customizable ride settings** via Harley s Ride Mode Control.

- Riders who **prioritize traditional Harley sound and feel**.

- Those who **prefer lower upfront costs and simpler maintenance**.

- Buyers concerned about **early reliability issues** or **long-term repair expenses**.

- Enthusiasts who want **maximum aftermarket support and tuning flexibility**.

---

### **Recommendation**

If you are **comfortable with a higher price point, modern technology, and potential complexity**, the M8 engine offers an exciting alternative to Harley s traditional V-twins. **Prioritize buying a 2021 or newer model**, as Harley has made significant improvements to reliability and build quality in these years.

- **Test ride multiple M8-equipped bikes** (Pan America, Sportster 1200, or LiveWire) to ensure the power delivery suits your preferences.

- **Check service records** if buying used, especially for turbocharger and fuel system health.

- **Budget for higher maintenance costs** consider setting aside **$1,500 $3,000 annually** for potential repairs.

- **Avoid early 2019 2020 models** unless you are prepared for potential recalls or fixes.

**If you prefer a more traditional Harley experience**, stick with a **V-twin model** (e.g., **Sportster, Softail, or Street Glide**), which will likely offer **lower costs, simpler repairs, and a more authentic Harley feel**.

Ultimately, the M8 engine is a **great choice for riders who want a modern, performance-focused Harley**, but it requires a **different mindset** one that embraces complexity in exchange for innovation.

Details:

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part #: 1840007318400073b prices

• $109.95-$129.99

specifications valvemotorcycleaz:

• for models: M8
• for makes: Harley
• for years: 2019-2025
• brand: Harley-davidson
• mpn: 18400073;18400073b
• type: Exhaust Valve
• country of origin: United States

general valvemotorcycleaz:

• Engines Engine Parts > Valvetrain Components > Engine Valves
• condition: Used

seller valvemotorcycleaz:

• city: Whitney, Texas
• rating: 99.8%
• # reviews: 10973

shipping valvemotorcycleaz:

• class: Standard
• cost: $0.00
• type: Fixed
• transit: 5-9 Days
• service: Standard

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• policy: No Returns

offer valvemotorcycleaz:

• sold: 0
• options: Ship-to-home
• availability: In Stock
• quantity: 2
• started: February 15, 2026

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