9 Most Common Harley Davidson Problems (Explained)

Harley-Davidson is the most iconic name in American motorcycles and remains one of the most popular bike manufacturers worldwide.

They’re some of the most expensive bikes on the market too, which is partially due to brand recognition.

If you’re in the market for a HD, it’s useful to know what to look out for.

In this article we’ll take a closer look at the most common problems associated with Harleys…

1. Faulty Cam Chain Tensioner System

One of the most notorious common problems with Harley Davidson motorcycles is the faulty cam chain system installed in multiple models throughout the 90s and 2000s. The Cam System stocks plastic “shoes” designed to reduce engine cam noise.  The plastic rubs away, causing metal-to-metal contact, friction, and overheating.

While metal-on-metal contact is always risky at high velocities, it’s especially hazardous in a small, air-cooled-only motorcycle cylinder like Harleys have, where heat is already a factor.

  • The friction and heat generated by the cam chain system once the plastic boots wear away often goes undetected until cam system failure or another form of related engine failure occurs.
  • While some consumer reports claim the cam chain failure doesn’t happen until the bike reaches 75,000 miles, others report a cam system-related engine failure within the first 15,000 engine miles.
  • The cam chain tensioner, cam bearings, cam support plate, and the camshaft are all at risk once the cam chain overheats.

Routine service and inspection are also a factor.

While Harley-Davidson technicians are aware of this problem and are trained to inspect the cam system during regular maintenance intervals, an unsuspecting home mechanic may not think to open up the motor and check the cam system while replacing their air filter and changing their oil.

Therefore, they miss the opportunity to replace the plastic cam chain tensioner boots at the early signs of wear long before failure occurs.

Online resources suggest Harley has updated the cam systems on their modern moto lineup. However, being aware of this common cam chain tensioner problem could save you time and money if you’re in the market for a used Harley Davidson motorcycle.

  • Using high-grade motor oil on your Harley will slow down the plastic boots’ deterioration.
  • Aftermarket oil fans are available for the various Harley models affected by this issue which also help to slow down the plastic’s wear.

2. Harley-Davidson Oil Pump Failure 

Harley-Davidson Oil Pumps have had a history of failures for various reasons. On the myriad models affected by the Cam system failure, the loose plastic bits clogged the oil filter. Models with the M8 engine were recalled for oil sumping.

  • Many Harley-Davidson oil-pump failures reports reference the Cam Chain Tensioner plastic boot issue covered in the previous section. As the plastic deteriorates and flakes off, the flakes make their way to the oil filter and clog it until it fails.
  • On all 2017–2019-year model Harley bikes with the Milwaukee 8 engine (M8), a faulty oil filter was causing oil sumping.
  • Oil sumping is when the oil lingers in the crankcase and cam gear case instead of returning to the oil reservoir.

The faulty oil pump in multiple Harley models failed to pump the oil back into its reservoir, so the various components, not in the crankcase or cam gear case aren’t getting the oil lubrication and cooling they need.

On the affected Harley models, oil pump failure causes sumping, leading to overheating, an increase in friction-induced engine wear, power loss, and engine failure if left unchecked.

  • If you’re experiencing symptoms of oil pump failure on a Harley Davidson motorcycle, you’re not alone, meaning the local HD technicians probably know what’s wrong with your year model bike and how to fix it.
  • And the only way to fix a faulty oil pump is to replace it with an upgrade that isn’t known for failure.

Related: 9 Common Problems with Indian Motorcycles (Explained)

3. Roller Bearing Failure

Many Harley Davidson motorcycles with twin cams manufactured in the late 90s and early 2000s had faulty roller bearings with low-quality cam support plates.  The issue resulted in many claims that a recall was filed to replace all affected units’ roller bearings and cam support plates.

Harley instructed their dealerships to upgrade any HD motorcycle models equipped with these faulty cam components at no cost to the owner.

According to online reports, some Harley dealerships will upgrade the parts on used models from the era if they are still equipped with the original faulty cam bearings and the weak stock support plate.

  • Your local Harley dealership can call the Harley factory and report the issue.
  • Since these problematic cam parts were installed on multiple Harley-Davidson models, the factory will require both of your engine serial numbers.
  • The first number is the vehicle identification number (VIN) that your bike is registered with off the left side engine casing at the base of the cylinders.
  • The second is the motor number off the bottom of the proper engine case.

If you bought your Harley motorcycle used and are experiencing the symptoms of the cam bearing failure, you may have the problematic ball bearings.

Contact your local dealership and find out if you are eligible for a free upgrade to the newer, improved roller bearings with the higher-quality cam support plate.

In addition to the faulty cam bearing problem, if your Harley is one of the year models with a defective oil pump, your bearings may fail due to a lack of lubrication.

The same could be true if your cam tensioner boots are flaking off and clogging your oil pump.

4. Brake System Failures

More than 250,000 Harley-Davidson motorcycles manufactured between 2008 and 2011 were recalled due to sudden brake failure. The brake failure was due to the brake fluid developing gel deposits which interfered with the performance of the various brake system components.

While some sources claim the problem was owners failing to flush their brake fluid regularly, consumer reports seem to point to the quality of the brake fluid as the culprit.

  • Harley owners claim the brake fluid on the various 2008-2011 Harley models experiencing brake failure deteriorated sooner than it should have as it was faulty.
  • The brake fluid would solidify into gel and jam up the Antilock Brake Systems Hydraulic Control Unit’s application valve.
  • Once the valve was stuck, the motorcycle’s brake system would fail.

Harley-Davidson recalled all models suspected of brake fluid failure, instructing dealerships to flush the brake fluid and replace the fluid every two years, regardless of motorcycle mileage.

Related: Harley Davidson Won’t Start? (Solved & Explained)

5. Fuel System Problems

Some Harley-Davidson Motorcycles experience various issues with their fuel system, including faulty fuel injectors, defective fuel pressure gauges, and vapor locks. Different Harley Davidson models were also fitted with fuel filters with shells prone to cracking.

After receiving field reports of riders experiencing fuel pressure loss while riding their motorcycles, Harley opened an official investigation.

  • HD found that multiple Harley Davidson bikes were fitted with fuel filters with shells that would crack from everyday use, causing a total loss of fuel pressure.
  • Fuel pressure loss causes erratic engine performance, frequent stall outs while riding, and starting problems.

If your Harley’s fuel filter cracks while you’re riding and the pressure loss stalls your engine, it can result in a collision, making this a significant problem to ask about when shopping for a used Harley.

6. Light Bulbs Blow Frequently

Harley-Davidson motorcycles may experience bulb burnouts more frequently than others due to improper factory installation or various electrical issues over the years.

Whether it was installed incorrectly or blown due to a faulty ground wire or a short in the wiring harness,  a blown light bulb can be enough to cause a collision.

 This makes repairing a Harley motorcycle with an electrical failure before you ride it extremely pressing.

Blown bulbs need to be repaired immediately before riding.

7. Brake Light Switch

One of the more severe light malfunctions caused over 250,750 various Harley Davidson moto models to be recalled after it caused a crash.

The unfortunate incident happened in 2010 when a Harley Trike was involved in a collision due to rear brake failure.

  • Harley investigated the incident to find that an electrical issue caused the brake failure.
  • The rear brake light switch installed on multiple Harley models lacked the integrity required to survive the standard operating temperatures of a Harley bike.
  • The brake switch would deteriorate from the heat, allowing brake fluid to leak.
  • Once the brake fluid leaks, the motorcycle’s brakes can fail, resulting in a crash, injury, or even rider fatality.

If you suspect an electrical failure with your Harley’s brake light switch is causing a fluid leak, take your bike to a Harley-trained tech and refrain from riding.

Inspecting your brake fluid levels regularly can catch fluid leaks before they cause accidents, provided you never ride your Harley with less brake fluid than suggested.  

8. The Clutch Won’t Disengage

Harley-Davidson motorcycles have reportedly experienced various clutch system failures over the years, a few of which have resulted in recalls. Several 2014-2015 models were recalled after multiple reports of Harley clutches failing to disengage.

Harley reported that the clutch failure was caused by the interference of bubbles they found in the master cylinder clutch.

  • After the initial failure report was filed in 2013, Harley’s Reall Investigation Committee launched a full investigation.
  • The investigation declared the cause of the issue was a defect in the master cylinder clutch itself and opened responsibility for two crashes and one injury.
  • While the initial claim affected about 20,000 units, sources claim that by the end of the fiasco, over 46,000 motorcycles.

If you are in the market for a used 2014-2015 Harley, inquire with the seller on whether it was affected by the recall and had its master cylinder rebuilt.

If you already own one and suspect you may have a faulty master clutch cylinder that’s causing your Harley Davidson motorcycle’s clutch not to disengage, swing by your local Harley dealership and find out if you are eligible for a free master cylinder rebuild.

At the very least, the Harley technician can flush your clutch master cylinder and get you safely back on the road with a fully functional clutch.

9. Won’t Start in Cold Weather

Many modern touring Harley models have had problems starting in cold temperatures below 50 degrees Fahrenheit. The problem was reportedly a parasitic drain on the battery by the various electronic bells and whistles these high-end cruisers employ while running on a standard 12V motorcycle battery.

  • Modern Harleys equip an impressive suite of electrical features like music, Bluetooth, navigation, engine monitors, and sensors.
  • These components pull power from the battery even after the bike is off in small doses.
  • Motorcycle batteries are charged by the stator, which converts motor power into voltage.
  • Therefore, the motorcycle’s battery can only be recharged while the bike is in motion.

Not only do batteries get weaker in the cold, but riders also ride less often, meaning their Harley Davidson motorcycles sit for more extended periods without charge.

Oil also thickens up in the cold, meaning the engine needs more power to move through the cold oil, making more than a few Harley Davidson motorcycles hard to start when it’s cold outside.

Related: How Long Do Harley-Davidsons Last? (Complete Guide)

What are the Pros and Cons of a Harley-Davidson Motorcycle?

Pros

  • The unique and dramatic signature roaring-engine sound.
  • An excessive number of Harley-Davidson dealerships in the United States and internationally.
  • Highly customizable; no shortage of add-ons and medication accessories from Harley and various aftermarket manufacturers.
  • Makes you a part of a large community of Harley-Davidson riders who regularly engage in social rides and charity events.
  • Harley-Davidson motorcycles are straightforward, low maintenance, and easy to work on.
  • Harley specializes in making comfortable, stylish, and fun-to-ride cruiser bikes.
  • The surplus of part availability makes Harleys easy to repair and keeps them on the road for decades.
  • Harley Davidson motorcycles played a significant role in both world wars, making them a part of American History.

Cons

  • Harley-Davidson motorcycles are set up differently than many European and Japanese motorcycles, meaning that certain services and repairs require specialized knowledge of Harley bikes.
  • Enthusiasts of other motorcycle manufacturers are often disappointed by Harley’s performance and reliability specs for the price point.
  • Harley Davidson parts, accessories, and apparel is overpriced, which fans say makes it seem like you’re paying for the name more than anything else.
  • Harley Davidson motorcycles are more expensive than other bikes while offering fewer features.

Related: Is a Harley a Good Beginner Bike? (15 Important Facts)

Sources:

10 Glaring Problems With Harley-Davidson Motorcycles Everyone Ignores (hotcars.com)

7 Engine Problems With Harley Davidson 96 Cubic Inch & (M8) (riderhow.com)

The 8 Most Common Harley-Davidson Problems & How to Handle Them (certifiedmastertech.com)