Written by: Emily Joswiak • February 11, 2025• Business

How To Choose Spark Plugs for Commercial Lawn Mowers

Keep your commercial lawn mower performing like new by choosing the right spark plugs. Explore tips to enhance reliability and extend engine life.

A commercial lawn mower is parked on the grass between several trees. The sidewalk has freshly cut grass scattered.

To keep your commercial lawn mower running, pay attention to your spark plugs. These small parts are an essential component for high-performing equipment. The right spark plugs tailored to your mower’s engine can boost reliability and extend its lifespan.

In this guide, we’ll cover the important factors to consider and offer practical tips for choosing the best spark plugs.

Understand Your Engine Specs

The first step is to understand your mower’s engine specifications. Check the owner’s manual or the engine model number to find information, such as the type and size of spark plug required. Common information includes the thread diameter, reach (length of the threaded portion), and heat range.

A larger mower built for long use may need a specific heat range to prevent overheating. Using the wrong plug can cause poor performance or engine damage.

Material and Durability Matter

There are three common types of material to choose from:

Copper is cost-effective, making it a good match for less demanding mowers. While it provides good conductivity, it has a shorter lifespan.
Platinum plugs can last up to twice as long as copper. They are ideal for moderately demanding applications.
Iridium is the most durable. Its fine electrodes conduct electricity efficiently, making it suitable for heavy-duty mowers.

If your mower operates for long hours in harsh conditions, consider iridium plugs for their extended service life.

Check the Gap

The spark plug gap is the small space between the electrodes where combustion ignites. Too large or too small a gap can be a problem. Many plugs come pre-gapped, but verify with a gauge before installation. Refer to your mower’s manual for the ideal gap size.

For instance, a standard plug may require a gap of 0.028 to 0.031 inches, while some higher-performance mowers need a larger gap.

Brand Compatibility

Sticking to reputable spark plug brands can make a difference in reliability and performance. While aftermarket options may seem tempting, always use spark plugs that meet or exceed the manufacturer’s original equipment specifications to avoid issues.

What if the Old Spark Plug Is Stuck?

If replacing an old spark plug becomes tricky, you might wonder how to safely remove stuck spark plugs from lawn mowers. The best approach involves using penetrating oil to loosen grime and corrosion. Allow the oil to sit for several minutes, then use a properly fitting socket wrench with gentle, steady force. Avoid applying too much pressure, as it could damage the plug or the engine’s threads.

Choosing spark plugs for commercial lawn mowers isn’t a one-size-fits-all process—it’s about aligning with your mower’s specific requirements. By following these steps, you’ll guarantee reliable starts, improved fuel efficiency, and long-lasting engine health.

Need help deciding? Keep a record of your spark plug choices and their performance so you’ll know exactly what works best for your mower in the future.

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Last modified: February 11, 2025