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Harley ACR Problems: Essential Troubleshooting Guide

harley acr problems

Enthusiasts and riders are well aware of the impressive performance and reliability that Harley Davidson offers to its customers. However, like any mechanical component, there can be occasional issues that arise. One specific component that has been a topic of discussion among Harley owners and technicians is the Automatic Compression Release (ACR) causing Harley ACR problems.

The ACR is an innovative feature built into Harley Davidson’s Milwaukee-Eight (M8) engines that help reduce the amount of effort needed to start the engine. The ACR system momentarily opens an exhaust valve at cranking, making it easier for the starter to turn over the engine. While this feature has provided convenience and improved engine performance, some owners have experienced problems with the ACR system.

In this article, talk about the role of the ACR in Harley Davidson motorcycles, common Harley ACR problems experienced by owners, and the potential causes of these problems. Understanding the function and potential challenges with the ACR system can help Harley owners more effectively troubleshoot any issues they may encounter and ensure their engine’s optimal performance.

Understanding Harley Automatic Compression Release

As riders of Harley Davidson motorcycles, we often come across technical jargon that might be confusing for some. One such term is “Automatic Compression Release” (ACR). In this section, we will explore the purpose of ACR and how it works on our bikes.

The Purpose of the ACR

ACR is designed to make starting our Harley Davidson motorcycles easier, especially those with high-compression engines. High-compression engines require more effort to turn over, which puts more strain on the starter motor and battery. ACR helps by momentarily reducing the engine compression during the starting process, making it easier for the starter motor to crank the engine.

How ACR Works

ACR is an electronically controlled system that is integrated into the engine’s cylinder heads. It functions by temporarily venting some of the pressure from the cylinders into the exhaust ports during the starting process. This is achieved through a series of complex holes and passageways, which are controlled by an electronic valve operated by the Engine Control Module (ECM).

When the start button is pressed, the ECM activates the ACR system, opening the valves and allowing the pressure to vent. This reduces the compression in the cylinders, making it easier for the starter motor to turn the engine over. Once the engine starts and reaches a predetermined RPM, the ACR system deactivates, and the engine resumes its normal compression and operation.

Common Harley ACR Problems

In this section, we will discuss some common Harley ACR problems that can occur. These problems can range from mechanical to electrical issues and can potentially cause starting and performance issues with your Harley Davidson motorcycle.

Stuck in Open Position

One issue we may encounter with the ACR system is that the valves can become stuck in the open position. When this occurs, it can lead to a lack of compression in the engine, making it difficult or even impossible to start.

This can be caused by a buildup of carbon deposits, dirt, or other debris on the valve or in the valve seal. To remedy this issue, we may need to clean the valve and valve seal or replace them if they are too worn or damaged.

Stuck in a Closed Position

Another problem we might face with the ACR system is when the valves become stuck in the closed position. In this case, the engine might experience excessive compression, making it hard to crank or start. This can also lead to premature wear of the starter and other related components.

Factors contributing to this issue may include a lack of lubrication, debris in the system, or a faulty ACR solenoid. Addressing this problem may involve cleaning the affected components, adding lubrication, or replacing the solenoid.

Electrical Issues

At times, we could encounter electrical issues with the ACR system. These problems may include damaged wiring, loose connections, or a malfunctioning control module. Electrical issues can cause the ACR system to function intermittently or not at all, affecting the engine’s starting and performance.

To resolve this, we may need to inspect and repair or replace any damaged wiring, tighten any loose connections, or replace a faulty control module.

Broken Components

Lastly, we might come across broken components within the ACR system, such as a damaged valve stem, a cracked valve body, or a broken spring. Broken components can hinder the proper functioning of the ACR system and result in engine starting and performance issues. To address this problem, we may need to replace the damaged components with new ones. Proper maintenance and regular inspection can help prevent these issues from occurring.

Identifying Harley ACR Problems

In this section, we will discuss common Harley ACR problems and how to identify them. We will cover symptoms of a malfunctioning ACR, along with diagnostic tools and methods to pinpoint the issue.

Symptoms of a Malfunctioning ACR

When Harley ACR systems fail, it can result in a variety of symptoms that may affect your motorcycle’s performance. Some of the most common signs to watch for include:

  • Difficulty in starting the engine
  • Hard cranking during engine startup
  • Low compression reading on a compression tester
  • Decreased engine performance
  • Noisy operation

Keeping an eye out for these symptoms can help you detect a malfunctioning ACR early and prevent further damage to your motorcycle’s engine.

Diagnostic Tools and Methods

Once you have identified the symptoms of a faulty ACR, the next step is to use diagnostic tools and methods to confirm the issue. Here are some tools and methods we recommend for diagnosing Harley ACR problems:

  1. Compression Tester: Using a compression tester, measure the compression of each cylinder. Low compression readings may indicate a malfunctioning ACR.
  2.  Visual Inspection: Examine the ACR’s electrical connections and wiring harness for any signs of damage or corrosion which might cause the system to malfunction.
  3.  ECM System Check: Harley Davidson’s Electronic Control Module (ECM) should have information about ACR-related issues. You can use a diagnostic tool to communicate with the ECM and check for any stored error codes.

Once you have narrowed down the issue using these methods, you can proceed to fix or replace the faulty ACR components to restore your motorcycle’s performance.

How to Troubleshoot Harley ACR Problems

In this section, we’re going to go through how to troubleshoot Harley ACR problems. We will cover visual inspection, checking electrical connections, and disassembling the ACR system.

Visual Inspection

Before diving into more complex troubleshooting, we suggest performing a visual inspection of the ACR system. Look for any signs of damage, such as cracked or broken parts. Ensure that the ACR system is properly installed and securely in place. If you notice any issues during the visual inspection, address them before proceeding to the next steps.

Checking Electrical Connections

Electrical connections are crucial for the proper functioning of the ACR system. We advise inspecting the wiring and connections for any signs of wear, damage, or corrosion.

Additionally, verify that the ACR system is receiving the correct voltage by using a multimeter. The Harley ACR system should operate on a 12V pulse signal. Check the voltage at the ACR connectors while the engine is running. If the voltage is not within the proper range, further investigation will be necessary to identify the cause.

Disassembling the ACR System

If you have checked the visual and electrical aspects of the ACR system and still face issues, it may be necessary to disassemble the system for a more in-depth inspection.

Before disassembling, consult your Harley Davidson’s service manual for specific instructions that pertain to your bike’s model and engine configuration.

During disassembly, inspect each component for signs of wear or damage that may be affecting the functionality of the ACR system. Pay special attention to the ACR solenoids, as they are responsible for opening and closing the ACR valves. These solenoids can become worn, stuck, or damaged over time, leading to Harley ACR problems.

Once you have inspected and addressed any concerns found during disassembly, reassemble the ACR system according to the service manual’s instructions. After reassembly, test the system to ensure proper functionality.

Preventing Harley ACR Problems

In this section, we will discuss how to prevent the occurrence of Harley Automatic Compression Release (ACR) problems. We will cover three key areas: Regular Maintenance, Proper Storage, and Monitoring Performance.

Regular Maintenance

Keeping your Harley’s ACR system in optimal condition is crucial for a smooth ride. Regular maintenance helps to maintain the performance of the ACR and prevent problems from arising. Here are some maintenance tips to consider:

  • Perform routine inspections of the ACR components, such as the electronic valve and passageways. Clear any buildup or debris as needed.
  •  Follow the manufacturer’s recommended service intervals for your Harley M8 engine, as stated in your owner’s manual.
  • ┬áReplace worn or damaged ACR components promptly to avoid further Harley ACR problems.

Proper Storage

Storage conditions can potentially impact the ACR’s functionality. We recommend following these guidelines to ensure that your Harley’s ACR system remains problem-free:

  • Store your motorcycle in a dry and cool area, away from fluctuating temperatures and humidity.
  •  Keep the battery in good condition and charged to ensure proper operation of the ACR’s electronic components.
  •  Protect the exhaust ports from direct exposure to moisture, which can lead to corrosion and obstruction of the ACR passageways.

Monitoring Performance

Monitoring your Harley’s performance on a regular basis helps you identify potential ACR problems early on, making it easier to address them before they escalate. Keep track of the following indicators:

  • Starting issues, such as sluggish or failed starts, might signal ACR malfunction.
  •  Pay attention to any noises or vibrations during the starting process, as they may be related to the ACR system.
  •  Monitor the engine’s compression levels using a compression tester to ensure that they are within the recommended range.

Together, these preventative measures will help you maintain your Harley’s ACR system and minimize the likelihood of problems.

Recalls and Known Issues

In this section, we will discuss some recalls and known Harley ACR problems that have affected Harley’s. It is essential to be informed about these problems to ensure the safety and performance of your ride.

Recently, Harley-Davidson issued a voluntary safety recall for certain 2021 Pan America 1250S, 2021 Pan America 1250, and 2021 Sportster S motorcycles due to an instrument cluster issue. Make sure to check for any recalls that could affect your model at safecar.gov or the Harley-Davidson website.

A known issue for pre-2007 Twin Cam engines is the camshaft chain tensioner failure. Although not a recall, it’s important to look out for this problem, especially on models made between 2003 and 2006, as it could lead to engine damage. Upgraded aftermarket parts are available to address this issue.

Another concern for Harley-Davidson owners is the clutch system. Over the years, some models have experienced clutch failures, leading to recalls. A few 2014 and 2015 model years were affected by faulty clutches, causing the clutch to not disengage properly.

Also, some Milwaukee 8 engine owners have reported power loss issues, often linked to the oil pump not pumping enough oil, causing the engine to overheat. Be mindful of your bike’s performance under extreme temperatures, and consider a thorough inspection if you experience this issue.

Here is a brief summary of some recalls and known issues:

  • 2021 Pan America 1250S, 2021 Pan America 1250, and 2021 Sportster S: Instrument cluster recall
  •  2003-2006 Twin Cam engines: Camshaft chain tensioner failure
  •  2014 and 2015 clutch system: Clutch disengaging problems
  •  Milwaukee 8 engines: Power loss due to oil pump issues

Stay informed about recalls and known issues specific to your Harley-Davidson motorcycle, and always perform routine maintenance and inspections to ensure a safe and enjoyable riding experience.

Wrapping Up Harley ACR Problems

We’ve come across common Harley ACR problems. While the technology is designed to ease the starting process and reduce strain on the starter motor, it appears that some owners have reported sporadic failure or sluggish starting.

We noted potential causes for these issues. For example, a weak or old battery often results in sluggish starting. We recommend checking the health of your battery and considering a replacement if necessary. Furthermore, we found that upgrading the compensator sprocket could alleviate issues related to ACR functionality, particularly for older models with the 96 or 103 engines.

In some instances, owners discovered that the ACR system was not functioning properly due to a lack of the appropriate voltage for operation. It is important to ensure that your ACR system is receiving the necessary 12 volts of power for optimal performance.

To summarize, if you’re experiencing Harley ACR problems, it’s crucial to inspect key components such as the battery, compensator sprocket, and voltage. By addressing these common issues and conducting regular maintenance, you can maintain the longevity and reliability of your Harley’s ACR system.