5 Harley 120R Engine Problems (With Solutions)

The Harley 120R engine, known for its impressive power and performance, is a favourite among motorcycle enthusiasts. 

However, some riders have reported problems such as overheating, a decrease in gas mileage, and premature wear in extreme cases. 

So, in this guide, I’ll share common Harley 120R engine problems with their solutions to make your ride smoother. 

Let’s begin!

Harley 120R Engine Problems

The most common Harley 120R engine problems are overheating particularly in the traffic, oil leaks, bolt failure, fuel economy problems, and hard to start especially in the morning.

1. Overheating in Traffic

Some users have reported that the engine tends to overheat when stuck in traffic. This was indicated by the engine light sensor blinking in one case.

It can be unnerving for riders, as it can lead to decreased engine efficiency, mechanical damage, and safety risks.

Factors like high RPM usage and limited airflow in slow-moving or standstill traffic can contribute to this problem.

The lack of air moving across the engine reduces its ability to dissipate heat, which causes the engine temperature to rise alarmingly.

To resolve this; you should ensure a quality oil cooler because it can significantly help in reducing engine temperature. 

Secondly, you should ensure timely maintenance and oil changes which also contribute to maintaining optimal engine temperature. 

Also, consider installing a heat management system, which can automatically adjust the engine idle speed to increase airflow when needed.

2. Oil Leak

A user mentioned an oil leak on the rear cylinder after 7,500 miles. The suspected causes were a head gasket, cylinder gasket, or possibly a piston ring.

This issue affects the overall performance of the machine but can also lead to significant mechanical damage if left unattended.

Oil leaks in the 120R engine are often caused by gasket or seal failures. These components are designed to prevent oil from escaping the engine’s different parts.

Over time, these components can become worn and fail, causing oil to leak out onto other engine parts.

To resolve this problem you should pinpoint the source of the leak. This may require a professional mechanic’s assistance for an accurate diagnosis. 

Secondly, you should replace the faulty gasket or seal with a new one. Also, regular maintenance and inspection can prevent this issue from recurring.

3. Bolt Failure

This issue pertains to the bolts that hold the engine components together. 

Due to the powerful output of the 120R, these bolts can sometimes fail, which leads to the loosening or detachment of critical engine components. 

This can cause serious issues as it may lead to the engine malfunctioning, or in extreme cases, completely breaking down.

So, to address bolt failure, you should ensure regular inspection and maintenance of the engine.

You should also tighten any loose bolts immediately to avoid progressive loosening that can lead to failure.

In case of worn-out or damaged bolts, you should replace them promptly with high-quality bolts that can withstand the power output of the engine.

4. Fuel Economy

While not necessarily a problem, some users discussed varying fuel economy figures, which might be of interest to owners.

This problem manifests as lower miles per gallon (mpg) than expected, which causes you to refuel more frequently. 

The increased fuel consumption can be a considerable inconvenience, particularly for long-distance riders.

To address this, you can consider multiple solutions. Firstly you should regularly service and maintain the engine, which helps ensure optimal fuel efficiency.

Keeping the engine in check by cleaning or changing the air filters, using high-quality engine oil, and checking the spark plugs will improve fuel economy. 

It would help if you also considered efficient riding techniques, such as avoiding aggressive acceleration and maintaining moderate speeds. 

5. Hard to Start

One of the other issues that 120R engine owners are facing is difficulty in starting the motorcycle. 

This problem manifests in various ways, such as the engine refusing to turn over, or the motorcycle starting up but then immediately shutting off.

The root causes can be numerous; however, the most common culprits are usually a faulty ignition system, a drained battery, or a clogged fuel system. 

So, you should check the ignition system, which includes the spark plugs and ignition coil for any damage or wear and tear. 

If they are in poor shape, you should replace them to resolve this problem.

In the case of a battery issue, you’ve to ensure that the battery is fully charged to resolve the problem. 

If the battery is old and unable to hold a charge, replacement might be the only option. 

Lastly, inspect the fuel lines and filters to check for any kind of blockage. Cleaning or replacing these components will resolve the problem, and enable your motorcycle to start smoothly.

2013 Harley 120R Engine Problems

One of the most common problems with the Harly 120R engine is overheating, which is particularly during slow rides or traffic situations. 

So, prolonged overheating can also lead to other issues such as oil leaks, causing the engine to run rough over time.

To address these issues; such as overheating and oil leaks, you should consider using high-quality synthetic engine oil and installing an oil cooler. 

Identify and fix the source of oil leaks by tightening or replacing seals.

2012 Harley 120R Engine Problems

Similarly to other models, 2012 Harley 120R owners have reported problems with excessive heat production, especially during long-distance rides in hot weather. 

This overheating can lead to discomfort and potentially damage the engine over time. Moreover, there have been instances of oil leakage and vibration issues. 

So, you should always ensure your 120R engine is regularly serviced and maintained by a professional to reduce the risk of these problems.

You can also check out the Harley 88 engine, 96 engine, 103 engine, 107 engine, 110 engine, 114 engine, 117 engine, 131 engine and Evolution engine Problems.