What Spark Plug to Use for Lawn Mower?

If you are tired of re-cranking your lawnmower just because the spark plugs are bad then it's probably time for you to change them. Sometimes for newbies, the question of the right spark plugs always arises.  It is not new that lawn and garden equipment are a source of major air pollution,a recent study shows that a lawnmower can produce enough pollution in 1hour than a car can in 13 hours of constant driving.

What Spark Plug to Use for Lawn Mower

Millions of people run their mowers on a daily basis and that translates to billions of gallons of gasoline burnt each year. The lifespan of a lawn mower runs into several years, so it is inevitable that you will occasionally have to change the spark plugs for better performance. Spark plugs can be damaged in a verity of ways, the most common being the improper use of the plug, while wearing down the plug is only likely to happen if you operate the mower on daily.

When should you change the Spark Plug?

  • Poor engine performance: If something is wrong with the engine’s spark plug, it won't run smoothly like it ought to. It will frequently require re-cranking to start again.
  • Excessive Fuel Consumption: Excessive oil consumption it's one of the most popular signs of a bad spark plug.
  • Distorted physical appearance: Physically inspecting the spark plug can reveal if it has been damaged in any way. Any distortion to the metal cap, electrode, gap or the flat top can render it useless.
Right Spark Plug for Lawn Mower

Lawn Mower Spark Plugs Vs Vehicle Spark Plugs

Automobile gasoline engines and lawn mower gasoline engine all use spark plugs to ignite the fuel and mix it in the gas cylinder chamber. They all work on the same energy principle by using high pulse voltage to force an electric spark to jump across the gap and the outer electrode. Although there is some interchangeability between a lawn mower spark plug and an automobile spark plug, most of them cannot be used because of physical differences.

What are those differences?

Difference in size

Size differences matter a lot when it comes to spark plugs. The thread sizes of lawn mower spark plugs are different from those of automobiles spark plugs. Ideally, most automobile spark plugs use a thread size of about 14mm thread why those of lawn mower range between 10 to 12 mm.  Because of these differences in thread sizes, they just won't fit into the same hole or the unit in which the plug is to be fit in.

The difference in tread length

Why lawn mower spark plugs have shorter thread sizes they are also shorter in length than auto plugs. The thread on many automobile plugs varies between half an inch and three-quarter of an inch long while many lawn mower engines use a plug that’s about ⅜ inch in length. The difference between size and length of spark plugs means they will not fit into the tapered hole specific for spark plugs in either the lawnmower or automobiles. You must use the specific plug for the right equipment.

Buying the right spark plug for your lawn mower

The two most important factors that differentiate each spark plug is the size and heat range of the plug. Apart from that, you need to make sure that they're the right fit for the proper gap of the motor engine.  To ensure you buy the right spark plug follow these simple rules:

  1. 1
    Use the Old Spark Plug: The simplest and most effective way to know the right spark plug to buy is to carry along with you the old spark plug to a specialty shop where they are sold. All you need to do is pull the rubber cap off the tip of the old spark plug that has been installed in the engine and undo it with a spark plug wrench. Write down the part number if possible, and carry the old spark plug to the shop for a replacement.
  2. 2
     Consult with your manual: If you can't find the old spark plug or for some reason it is missing from where it has been pre-installed, consult with the owner's manual to locate the right spark plug to use. Write down the make and model of the lawnmower as well as the model number of the engine.  Take these details to the shop so that they will find the specific plug for you.

Spark plug types and gaps

Flathead engines are known as L head or side-valve engine normally used for walk-behind lawn mowers and seldom used for pressure washers. The replacement part for the standard resistor spark plug is either, 796112S,802592S, or 5095 and the spark plug gap is 0.030 inch. Electromagnetic suppression spark plug EMS replacement spark plug number is 697451 with a spark plug gap of 0.030 inches. Consult with spark plug table chart for more details.

Where to buy the right spark plug

Spark plugs are an extremely popular engine component to buy. They are very cheap and with as little as three or four dollars you can buy a replacement spark plug for your engine. They are mainly sold at stores and locations that sell engine spare parts. You will find them in common places where combustion engines are sold.

If you can locate a store that supplies lawn mower, they will also have engine components for sales and that must include spark plugs. Online stores and retail giants also stock spark plugs but you have to know what you are looking for to purchase the right one. With a shop that sells engine components, you will have the opportunity of speaking with a professional that can guide you to the right spark plug to purchase.

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Brice The Botanist
 

Growing up in Ventura, California famous for it's rich gardens. Brice has spent most of his life trying to help make the world greener. Studying Botany at CSRA, he's made it a lifelong passion to greenify every home.

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