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Harley 103 vs 107: Evolutionary Or Just A Step Backwards?

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Unraveling the much-debated world of Harley-Davidson engines, the ‘Harley 103 vs 107: Evolutionary or just a step backwards?’ discussion promises to rev up your motorcycle knowledge. Enthusiasts and beginners alike grapple with the subtleties and complexities tied to this iconic brand’s engine evolution.

If you’ve found yourself caught in the middle of the Harley 103 vs 107 debate, or if you’re simply trying to steer clear of the Milwaukee 8 problems or potential Harley 107 problems and Harley 103 issues, you’re in the right place.

From performance torque to fuel efficiency, from rattling noises to ride stability, we delve deep, diagnosing the nuisances that might influence your riding experience or even your next purchase. So let’s hit the throttle and thrust into this Harley engine showdown, busting myths, transcending hearsay, and embracing the thundering truth. Let’s get rolling shall we?

An earlier comparison: Twin Cam 88 vs 96: Dual Cam Shootout (What’s Better?)

What Are The Major Differences Between The Two Engines

The biggest difference between the Harley 103 and 107 is their size. The 103, also known as the Twin Cam 103, has a displacement of 103 cubic inches (or 1,690cc), while the 107, part of the Milwaukee-Eight series, has a displacement of 107 cubic inches (or 1,753cc). This difference in size translates to more power for the 107, offering riders a more robust and thrilling ride.

Milwaukee 8 vs Twin Cam Engine Design Differences

Beyond displacement, the Milwaukee-Eight 107 and Twin Cam 103 engines differ in their design. The 107 is part of Harley’s newest engine line, the Milwaukee-Eight series, which features four valves and two spark plugs per cylinder, allowing for better combustion efficiency, more power, and cooler running temperatures. The 103, on the other hand, belongs to the older Twin Cam series, which has two valves per cylinder and a single spark plug.

Here’s an example of a dual spark configuration on a motorcycle:

an infographic showing an example of the dual spark plug configuration in a motorcycle engine

Related articles:
> Harley Twin Cam Problems
> Harley Twin Cam Years to Avoid

Benefits of Each Style Engine

Each of these engines offers its unique advantages. The Twin Cam 103 is known for its reliability and easy maintenance, making it a favorite among long-term Harley owners. On the other hand, the Milwaukee-Eight 107 delivers more power and a smoother, cooler ride, thanks to its advanced design and extra valves.

Keep reading: Super Glide vs Wide Glide

How Do They Stack Up Performance Wise?

When it comes to performance, the Milwaukee-Eight 107 generally has the upper hand. Thanks to its larger displacement and more efficient engine design, the 107 offers more horsepower and torque. However, the Twin Cam 103 still delivers a satisfying ride, with plenty of power for cruising and touring.

Previous articles:
Harley 88 vs 107: An In-Depth Comparison

Harley 96 vs 103
Harley 88 vs 96 vs 103: An In-Depth Engine Comparison

Harley 103 Performance Specifications

The Twin Cam 103, featured in many Harley Davidson motorcycles, offers a peak torque of 95 ft-lb at 3,750 rpm. It’s a reliable powerhouse that many riders swear by for its smooth performance and low-maintenance design.

And, it helps to have this available: Best Tuner for Harley 103 Gets Revealed (By An Expert)

Harley 107 Performance Specifications

The Milwaukee-Eight 107, on the other hand, offers a peak torque of 111 ft-lb at 3,250 rpm. The extra torque, coupled with the engine’s improved efficiency and cooling, results in a high-performing engine that offers a smooth, powerful ride.

Got an itch for some gnarly Harley performance? Read this: Harley Stage Kits Explained

Direct Comparison

When compared directly, the Harley 107 does offer more power and a smoother ride than the 103. However, the 103 is still a reliable, high-performing engine that many riders love. Ultimately, the choice between the two may come down to personal preference and riding style.

Keep reading:
> Who Makes Harleys Oil and Filters
> Who Manufactures Harley Davidson Spark Plugs

How Do The Two Compare In Terms of Reliability?

As far as reliability goes, both the 103 and the 107 are solid engines. The 103 has a proven track record of reliability and durability, while the 107, despite being newer, has also shown to be reliable in its own right.

Related articles:
Electra Glide vs Street Glide
– Switchback vs Road King: Comparing Touring Experiences

Harley 103 Common Problems

Despite its reliability, the Twin Cam 103 is not without its issues. Some common problems reported by riders include issues with the cam chain tensioner and problems with the engine running hot.

You should also know:
Harley Davidson 103 Oil Capacity: A Detailed Guide
– Harley Davidson 103 Primary Oil Capacity (Full Explanation)

Harley 107 Common Problems

As for the Milwaukee-Eight 107, some riders have reported issues with the compensator causing primary chain and clutch failures. Additionally, some have reported lifter and camshaft problems causing engine failure.

harley 107 problems infographic to show the common problems associated with the engine

What Does The Community Say About The Engines?

Rider opinions vary when it comes to the Harley 103 vs 107 debate. Some riders swear by the reliability and performance of the 103, while others prefer the increased power and smoothness of the 107.

Related: Forward vs Mid Controls

Harley Davidson Forum Comments

On Harley Davidson forums, the debate is often heated. Many riders stand by their preferred engine, citing personal experience and performance as the reasons for their choice.

Reddit Comments

On Reddit, the discussion is similar. Many riders share their experiences with both engines, often leading to a healthy debate about the merits of each.

Keep reading:
> Best Battery for Harley Davidson Motorcycles
> Best Spark Plugs for Harley Davidsons


Frequently Asked Questions

In this section, we’ll address some common questions about the Harley 103 and 107 engines.

Is the Harley 107 a better engine than the 103?

While the 107 offers more power and a smoother ride, the 103 is a reliable, high-performing engine. The choice between the two often comes down to personal preference.

What are some common problems with the Harley 107?

Some riders have reported issues with the compensator causing primary chain and clutch failures. Additionally, some have reported lifter and camshaft problems causing engine failure.

What are some common problems with the Harley 103?

Some common problems reported by riders include issues with the cam chain tensioner and problems with the engine running hot.

Is the Harley 107 worth the upgrade from the 103?

The answer to this question is subjective and depends on your riding style and preferences. If you value higher power and a smoother ride, then the 107 may be worth the upgrade. However, if you’re happy with the performance of your 103, there may not be a need to upgrade.


In conclusion, both the Harley 103 and 107 engines have their strengths and weaknesses. Whether you prefer the proven reliability of the 103 or the increased power of the 107, both engines offer a unique riding experience that many Harley owners love.