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Choosing the right spark plugs for generator

BISON is known for producing high quality spark plugs. There are many factors to consider when choosing the right spark plug. Read this guide to learn more.

Table of Contents

Introducing BISON generator accessories manufacturer expert guide on generator spark plug replacement.

This guide serves as a valuable resource, furnishing you with critical data to empower your decision-making process for the optimal spark plug.

We lay out vital considerations in your selection journey, guaranteeing your final choice aligns seamlessly with your specific requirements.

Begin the enhancement of your generator’s performance today. Choose the right spark plug, choose excellence.
We recommend referring to your Owner’s Handbook for model-specific recommendations.

Start enhancing your generator’s performance today with the right spark plug.

BISON generator spark plug display

View the user manual

The first step: is to look at the owner’s manual that came with your generator. You’ll find every piece of information you need there, so don’t throw it away.

From our personal experience, information about spark plugs is provided in the maintenance section. Usually, the specific make and model are noted there.

Note the required gap

When choosing a spark plug for your portable generator, one of the few features you’ll want to pay close attention to is the suggested gap between the two electrodes.

Note the required gap

As mentioned, you can find this number in the user guide or manual.

The most common generator spark plug specifications are as follows:

Socket size:  16mm (5/8”) or 21mm (13/16”)

Gap size: 0.028” – 0.031” (0.7mm – 0.8mm)

In our experience, most portable generators require spark plugs with a gap size of 0.028” – 0.031” (0.7mm – 0.8mm). Remember that your particular generator may have a different spark plug gap.

That’s why you always need to double-check it in the manual.

You should also have a 5/8” (16mm) or 13/16” (21mm) socket and ratchet ready in case you want to replace the spark plugs yourself.

You need to be aware that inserting a different type of spark plug than recommended could cause severe damage to your engine and be very expensive to repair.

That’s why you should always get your generator’s correct model and type.

BISON C54 spark plug

Follow the advice

You will find information on the required gap measurements in the maintenance section of your owner’s manual and additional advice on choosing the right spark plug.

These include:

  • Mentions of compatible brands
  • Specific models for each brand
  • Allowable electrode materials

Remember that if you decide not to follow the recommendations in your owner’s manual, your generator’s warranty may be voided.

Pursue quality instead of price

Last, it would be best to never save on your generator’s spark plugs. Preferring a low price over a high-quality product can lead to many worries later.

Instead of trying to save a few bucks, spend a little more and get high-quality spark plugs from BISON.

Keep in mind that individual generators may require different types of spark plugs.

Seek professional help

Are you worried about choosing the wrong spark plugs and damaging your engine? If you are not sure how to choose the right spark plugs for your alternator, seek help from BISON experts.

It’s better to admit you need help than to wreak havoc on your engine.

Have a spare plug on hand

BISON’s final recommendation is to purchase at least a few spare spark plugs as soon as possible. Since this spare part isn’t expensive and won’t spoil if stored properly, you can purchase at least a few beforehand.

Once the power is out and the spark plugs are damaged, you might have difficulty finding the correct model in your area.

Also, spark plugs can become challenging once hurricane season begins.

Engine size and type

When selecting spark plugs for a generator, the size and type of the engine must be considered. Typically, the owner’s manual contains this information. Spark plugs have different heat ranges, determining how quickly the plug transfers heat from the combustion chamber. Using the wrong heat range can result in poor engine performance, premature wear, and even engine damage.

For example, generators with smaller engine sizes (e.g., 1000-2000 watts) may require spark plugs with cooler and hotter ranges to prevent fouling. On the other hand, generators with larger engine sizes (e.g., 5000-7500 watts) may require spark plugs with a higher thermal range to prevent an explosion.

Also, some generators may have a specific engine type, such as OHV (overhead valve) or OHC (overhead cam). Selecting spark plugs compatible with your engine type is critical to ensuring proper ignition and performance.

Operating conditions

Different conditions, such as temperature, altitude, humidity, and fuel quality, can affect the performance of spark plugs. For example, a high-altitude location may require different spark plugs than a lower-altitude location due to changes in air pressure. Also, extreme temperatures may need another spark plug type to ensure proper ignition.

Thread size

The thread size of the spark plug is also essential when choosing a replacement spark plug. It refers to the diameter and pitch of the threads on the plug that screws into the engine cylinder head. Using spark plugs with the wrong thread size can damage your engine’s cylinder head and cause the spark plugs to seize, making them difficult to remove.

To determine the proper thread size, consult your owner’s manual or a qualified technician. Although other diameters are available, 14mm and 18mm are portable generators’ most common thread sizes.

When shopping for replacement spark plugs, double-check the thread size to ensure they are compatible with your generator’s engine.

Finding the Right Alternator Spark Plugs


Selecting the proper spark plugs for your BISON generator ensures efficient and consistent operation. Before making a purchase, it is important to consider details such as spark plug size, composition, and lifespan. Choosing the correct spark plug can improve the efficiency and life of the generator. If you’re still trying to decide which spark plugs to use, read BISON’s advice or seek the guidance of an expert. With the right spark plugs, your generator can run for years without interruption.

choose spark plug FAQ

Depending on the maker and the particular circumstances in which the generator operates, the longevity of a spark plug can differ. Typically, premium spark plugs have the ability to endure for several thousand hours before a replacement becomes necessary.

No, it will help if you only use the spark plugs recommended by the generator manufacturer. Using the wrong type or size of spark plugs can damage your generator and be potentially dangerous.

Search for spark plugs made from superior quality materials like copper. These materials are more resilient and offer enhanced performance over the long term.

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