What is Double Overhead Cam (DOHC)?

Since time immemorial, motorcycle brands have come up with pretty innovative ways to make their motorcycles unique. The first wave of innovation in the global motorcycle industry surfaced in the form of motorcycle engine technology. Motorcycle engines of the yesteryears were unreliable, bulky, and inefficient. That had to change and motorcycle manufacturers knew that. This was the reason why, motorcycle brands came up with pretty impressive ways to make their engines reliable, durable, efficient, and performance-oriented.

One of the ways that motorcycle brands chose was to implement car engine technologies into motorcycle engines. One of those selected technologies was DOHC.

DOHC stands for dual overhead camshafts. 

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So What Exactly is a DOHC Engine?

A Dual Overhead Cam engine unlike the run-off-the-mill motorcycle engine comes with an additional camshaft. This additional camshaft makes the movement of the pistons within the engine seamless. The additional camshaft also helps to make the movement of the engine head valves seamless. The dual overhead cam engine can be labelled as an enhanced single overhead camshaft engine. Presently, motorcycle engines with dual overhead camshafts are considered the epitome of motorcycle engine innovation.

What are the Advantages of DOHC Engines?

The primary advantages of a dual overhead camshaft motorcycle engine are enunciated in the sections below.

  • DOHC motorcycle engines have more valves at the intake and exhaust ends of the engine. Hence, it is natural for DOHC engines to offer more performance per litre of spent petrol.

  • DOHC engines are more refined compared to SOHC engines. 

  • DOHC engines are compatible with valve time-altering technologies like Variable Valve Timing. Hence, even if DOHC engines are less fuel efficient, they can be optimized for fuel efficiency with aftermarket tuning. This is the reason why, revered motorcycle brands these days tend to equip their engines with two camshafts. With the help of this step, bike brands can eradicate the need for their customers to tune their motorcycles in aftermarket tuning studios. After-market tuning of engines usually nullifies the warranty of the motorcycle and its engine. Hence, this step should be avoided like the plague by motorcycle owners at all costs.

  • DOHC engines have more control over their intake and exhaust valves. SOHC engines, on the other hand, do not offer this advantage as they do not have additional valves.

  • DOHC engines offer enough wiggle room to engine designers especially when it comes to the positioning of valves and spark plugs. DOHC engines allow engine designers to place the valves at angles. The angular positioning of valves enhances the maximum flow of air through the intake end of the engine. Furthermore, DOHC engines, most of the time, come with spark plugs positioned in the middle. This allows the engine to have an enhanced ignition cycle that results in better performance and low emissions.

What are the Disadvantages of DOHC Engines?

A dual overhead DOHC engine also entails its fair share of disadvantages and they are as follows:

  • DOHC engines are complex to design.

  • DOHC engines are heavier compared to SOHC engines.

  • The designing and fabrication costs of DOHC engines are higher compared to SOHC engines. Hence, motorcycles with DOHC engines would entail steep price tags.

  • DOHC engines, unlike SOHC engines, rely on a complex belt or chain drive system to operate properly. It means that there are more movable parts that can break. It also means that the maintenance and repair costs of DOHC engines are higher compared to SOHC engines.

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What Should the Average Motorcyclist Choose? Should They Go for a DOHC or a SOHC Engine Powered Bike?

DOHC engines come with four valves for each cylinder in a motorcycle engine. In a DOHC engine, two valves work at the intake end of the engine. The remaining two work at the exhaust end of the engine. 

DOHC engines are more performance-oriented however; they tend to consume more fuel. Furthermore, maintaining a DOHC engine is a costly affair. Hence, if a motorcyclist has no problem owning a bike that entails high ownership costs then they can go for a bike with a DOHC engine. On the other hand, if a motorcyclist is budget-conscious then they should buy a bike with a SOHC engine.

It is as simple as that!

To learn more, contact a professional associated with the fabrication or repairs of engines.