What is a Motorcycle’s SOHC Engine?

SOHC Engine

What is a Motorcycle’s SOHC Engine? If you’re a motorcycle enthusiast like us, you’ve probably heard the term “SOHC motorcycle engine” mentioned before, and you’re likely eager to learn what it is and how it differs from other motorcycle engines.

A motorcycle can become an essential part of our lives, and when that happens, we become more interested in understanding its composition, what changes we can make to it, or simply develop a deeper curiosity about it.

Among the various types of motorcycle engines, you’ll come across SOHC, DOHC, VTEC, and more. In one of our previous articles, we shared information about “What is a DOHC Motorcycle Engine,” and now, we want to focus on SOHC motorcycle engines.

All of this is to help you develop a deeper passion for motorcycles because once you start learning more about them, you’ll undoubtedly want to know more and more.

SOHC motorcycle engines are an abbreviation for Single OverHead Camshaft, which means that the camshaft is located in the cylinder head and actuates both the intake and exhaust valves simultaneously, usually through disc or hydraulic lifters.

These engines are known for their cost-effectiveness due to a reduction in the number of moving parts. While this may sound like it compromises quality, it’s not the case. Let’s delve into some of the features of SOHC motorcycle engines.

We invite you to keep reading to discover more about your motorcycle.

Features of an SOHC Motorcycle Engine

As mentioned earlier, an SOHC motorcycle engine has a camshaft located in the cylinder head, which actuates both the intake and exhaust valves simultaneously through disc or hydraulic lifters. This might sound confusing, so let’s simplify it.

The “camshaft” is a crucial component within the engine, as it’s part of its valve timing system. It consists of a mechanism with a shaft that has various lobes, each with its unique size and shape, depending on its intended use.

These lobes actuate different functions of the valve mechanism in repetitive cycles. This causes the intake and exhaust valves to open and close at the right times, allowing for the proper intake and exhaust phases in four-stroke combustion engines.

As the camshaft rotates, its lobes push down on the valves to open them, while closing is achieved by springs acting in the opposite direction.

Most common engines have a single overhead camshaft and feature one intake and one exhaust valve per cylinder. In contrast, multi-valve engines, which have more than two valves per cylinder, are typically DOHC (Double Overhead Camshaft) engines, meaning they have two camshafts in the cylinder head.

Differences Between an SOHC Motorcycle Engine and Other Engines

In our previous article about “What is a DOHC Motorcycle Engine,” we mentioned the difference between DOHC and SOHC engines, focusing on their camshaft configurations.

The primary difference between SOHC and DOHC engines lies in how they handle valve functions. This distinction allows SOHC engines to be lighter and simpler. Some consider them “standard” engines, although they perform the same functions as other engines; it’s the approach that differs.

An SOHC motorcycle engine uses a single camshaft to perform both intake and exhaust functions, while a DOHC engine has two separate camshafts for these functions.

Each engine is designed for specific purposes. A valve train must be lightweight to minimize rotational inertia. Additionally, a heavier valve train would require more energy to open and close the valves, consuming usable energy and affecting fuel efficiency.

SOHC motorcycle engines gained popularity faster in the market. SOHC engines became popular in the 1960s and 1970s, while DOHC engines had to wait until the 1980s to be used more frequently.

See more: Break-in on the New Motorcycle: Yes or No?

Advantages and Disadvantages of an SOHC Motorcycle Engine

By this point, you’ve likely noticed the differences between SOHC motorcycle engines and other engine types. To help you decide whether an SOHC engine is a good choice for your motorcycle or if another type suits you better, let’s explore some advantages and disadvantages.

Advantages of an SOHC Motorcycle Engine

Some of the most important mechanical advantages of SOHC engines to consider are:

  • Lightweight: Since they use a single camshaft for both intake and exhaust functions, they can eliminate rocker arms, reducing their weight significantly.
  • Fewer moving parts: Optimization of tasks results in fewer moving parts during engine assembly, leading to a quicker and simpler installation process.
  • Lower cost and compact size: Fewer parts mean reduced manufacturing costs and a smaller engine size, making it a competitive choice for motorcycles.

Disadvantages of an SOHC Motorcycle Engine

To provide a complete picture of what it’s like to have an SOHC engine in a motorcycle, here are some potential disadvantages:

  • Reduced performance: The engine’s performance may not match that of other engines, depending on the motorcycle’s intended use.
  • Decreased power: An SOHC engine typically has less power than a DOHC engine, even if other aspects are identical. This is because while tasks are optimized for efficiency, some power potential may be sacrificed.
  • Difficulty in spark plug placement: In the case of a 4-valve SOHC design, the spark plug cannot be placed in the central position, potentially leading to incomplete combustion.


After learning all this, you now have a good understanding of SOHC motorcycle engines. Your doubts about this type of engine have hopefully been cleared, and you’ve gained a deeper knowledge of your motorcycle.

Whether you choose an SOHC or DOHC engine, the important thing is that you can enjoy your motorcycle. Both types of engines have their merits and are designed for different purposes.

If you’re looking for guidance on which engine suits your motorcycle best, you can browse our catalog and reach out to us; we’re here to assist you.

Feel free to leave any questions or share your knowledge about these engines in the comments, and we’ll be at your service to provide guidance.

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