Honda GX690 Spark Plug Gap, Number, and Socket Size Guide

Did you know that maintaining the correct spark plug gap can increase your Honda GX690 engine’s efficiency by up to 30%? That’s a significant boost you shouldn’t ignore.

In this guide, we’ll discuss everything you need to know about your Honda GX690 spark plug, the number, the ideal gap, and even the socket size required for installation or removal.

These details are vital to keeping your engine running smoothly and efficiently, just like it belongs on top of its performance game all year round!

So gear up as we delve into these technical aspects together, ensuring you get the most out of your Honda GX690 engine’s performance.

Honda GX690 Spark Plug Gap, Number, and Socket Size Guide

Key Takeaways

  • Maintaining the correct spark plug gap can increase the efficiency of the Honda GX690 engine by up to 30%.
  • The recommended spark plugs for the Honda GX690 engine are BPR6ES (NGK) or W20EPR-U (DENSO), with a gap of 0.7-0.8 mm (0.028-0.031 in).
  • The socket size needed for spark plug installation or removal is 20.6mm or 13/16 in.
  • The recommended spark plug for the Honda GX690 engine is NGK ZFR5F (98079-5587G), and the socket size required is 5/8′ (16mm).


For your Honda GX690 engine, you’re gonna need the ZFR5F (NGK) 98079-5587G spark plug or its equivalent, with a gap size just right between 0.028′ and 0.031′.

Honda recommends this specific spark plug for the optimal performance of your machine. The number ‘ZFR5F’ signifies the model of the NGK brand spark plug, while ‘98079-5587G’ is its product code.

The set gap size plays a crucial role in your engine’s ignition system. When correctly gapped, it helps ensure efficient fuel combustion, resulting in smoother running and increased longevity of your engine. If too wide or too narrow, this could lead to misfires or decreased power output.

Now let’s talk about alternatives. Though Honda highly recommends the NGK ZFR5F for use in their GX690 engines, there may be situations where you’ll need an equivalent spark plug that can perform just as well under similar conditions. For these instances, always make sure to match not only the type but also the appropriate gap size.

Remember that proper maintenance of your spark plugs contributes significantly to overall engine health and performance. Regular inspection for wear and correct gapping should be part of your routine checks on all parts – making sure everything’s working together perfectly for you and your trusty Honda GX690 engine!


When it comes to wrenching your engine’s fiery heartbeat, you’ll need a 5/8′ (16mm) tool. This is the socket size required for the spark plug of your Honda GX690 engine. But what does this mean, exactly?

The socket size refers to the dimension of the tool socket that fits over the hexagonal part of the spark plug.

Here are some key points about this:

  • A 5/8′ (16mm) socket size is standard for many engines, including your Honda GX690.
  • Socket sizes are crucial for effective maintenance – using an incorrect size can damage both your tools and the spark plug itself.
  • Ensure you have a high-quality 5/8′ socket wrench or spark plug remover in your toolkit.
  • Spark plug sockets often come with rubber inserts to protect the ceramic part of your spark plugs during removal or installation.
  • Always follow manufacturer recommendations when selecting tools and equipment for engine maintenance.

Remember that even though small details like these may seem insignificant, they’re fundamental in maintaining efficient performance.

You’re not just looking after an engine; you’re caring for a vital component of something bigger: Your sense of freedom and adventure on road trips or work projects, powered by Honda’s reliable technology.

Frequently Asked Questions

What are the symptoms of a faulty spark plug in a Honda GX690 engine?

If your GX690’s spark plug is faulty, you’ll notice issues like poor fuel economy, difficulty starting the engine, inconsistent acceleration, and a rough idle. Misfiring or engine surging may also occur.

How often should the spark plug of a Honda GX690 be replaced?

You should replace the spark plug on your Honda GX690 after every 300 hours of use or once a year, whichever comes first. Regular maintenance ensures optimal engine performance and prolongs its lifespan.

Are there specific brands of spark plugs that are recommended for use in a Honda GX690 engine?

Yes, for your Honda GX690 engine, Honda specifically recommends NGK brand spark plugs. They’re designed to provide optimal performance and longevity when used in this specific model of engine.

Will use a spark plug with the wrong gap damage the Honda GX690 engine?

Yes, using a spark plug with an incorrect gap can indeed damage your Honda GX690 engine. It’s like throwing a wrench into the works – it can lead to poor performance and potential internal damage.

Can a spark plug from another engine model be used in the Honda GX690?

While it’s possible to use a spark plug from another engine model in your Honda GX690, it’s not recommended. Using the correct, specified spark plug ensures optimal performance and prevents potential engine damage.


So, you’ve got all the key details on your Honda GX690 spark plug. You know it’s BPR6ES (NGK) or W20EPR-U (DENSO), and it needs a 0.7-0.8 mm gap for prime performance.

You also understand that a 20.6 mm socket is necessary for removal and installation. Isn’t it great to be well-informed?

Remember, check every 100 hours and replace every 300 hours or annually to keep your engine running smoothly!

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