A Spark plug is a small component. As such it does not weigh much when compared to the behemoth weight of a motorcycle or a car. Still, it’s a simple curiosity to know its weight.
So, how much does a spark plug weigh? A spark plug should typically weigh between 25 to 60 grams (0.88 to 2.12 ounces). The average weight of an automobile spark plug will be around 45 grams (1.59 ounces).
The average weight mentioned here is not definitive since the spark plug can weigh differently depending on numerous factors.
Let’s deep dive more into these factors.
Spark plug weight
A spark plug’s weight typically ranges between 25 to 60 grams (0.88 to 2.12 ounces).
The average weight of spark plugs used in automobiles will be around 45 grams (1.59 ounces).
We tested the weight of 12 spark plugs to arrive at this average figure. Although by no means this is a comprehensive study, we believe this gives a fair idea of what an average spark plug weight is.
The exact mean weight of the spark plug was 46.01 grams (1.62 ounces) and the median was 46.07 grams (1.62 ounces).
What was more interesting in this small sample study is the lack of correlation with the type of spark plug. We were not able to see any weight difference with respect to copper, platinum, and iridium spark plugs.
Again, we understand the lack of correlation might have also to do with the limited sample size we had for this study. Still, from our observation, we believe the type of center electrode used material has little impact on the spark plug weight.
Having said that, we do believe the overall materials used in spark plugs will definitely impact the weight.
That brings us to the next section – factors affecting the weight of spark plugs.
Factors affecting spark plug weight
Although there are several different parameters, the major factors affecting spark plug weight are as below:
Type of materials used
Spark plugs are typically made of steel shell, sintered alumina or aluminum oxide insulator, and a copper, platinum, or iridium center electrode.
These material compositions in a spark plug can easily change the weight of the spark plug.
Take the hot spark plug for example. The insulator nose will be longer. Compare that to the cold spark plug, the insulator nose will be shorter.
These small material design differences are enough to create small weight differences in spark plugs.
Spark plug design and hence, weight also varies from manufacturer to manufacturer.
Heck, even their heat ratings vary.
So, it’s no shocker that different manufacturers have slightly different spark plug designs and hence, weights – even when the specifications are almost the same. And can be used interchangeably.
Usage and Application
Another factor that can result in different spark plug weights is the intended usage and application.
A spark plug intended for a motorcycle gasoline engine can have a different weight than that is designed for a lawn mower engine.
The same argument can be extrapolated for the resistor and non-resistor spark plugs as well.
Other spark plug specifications
Spark plug voltage
Typically, a spark plug needs a high voltage of 15,000 to 20,000 volts to generate the electric spark in the engine.
In modern spark plugs, the voltage can be as high as 60,000 volts depending on the design, spark plug type, and vehicle model.
Modern automotive spark plugs generate a far higher voltage spark than the old ones. The old spark plugs operated with a voltage of 10,000 volts. Modern spark plugs operate as high a voltage as 60,000 volts.
A high-voltage spark has its advantages. Simply put, a high-voltage spark allows for a more energetic and complete ignition. The sparks generated are hotter, larger, and longer lasting.
For more details, here is our post on spark plug voltage.
Spark plug gap
For motorcycles, the typical spark plug gap is recommended between 0.8mm to 1.0mm (0.031 inches to 0.039 inches).
However, the best way to check the recommended spark plug gap is to look up the user manual for your motorcycle.
Spark plug cost
A typical spark plug costs less than $10 with a copper spark plug available at just $2.5.
Platinum and iridium spark plugs are costlier than copper spark plugs. Still, you can easily get them for around $7 to $10.
Iridium spark plugs are available at even high prices though depending on your desired specifications. However, even the best iridium spark plugs for automobiles should be available for less than $15.
If you are buying a set of spark plugs, then a set of 4 or 6 spark plugs should be in the price range of $10 to $60. The price depends on the spark plug type and how many plugs are there in a set (usually it is 4 or 6).
Spark plug heat range
The optimum spark plug temperature range is between 500 to 800-degree celsius (or between 900 to 1500 degrees Fahrenheit).
The temperature here is referred to as the center electrode temperature since that is where the spark is generated.
If the spark plug is operating at a temperature below the optimum range, then you will start noticing carbon deposits. The low electrode temperature allows the unburnt fuel to start depositing.
If, on the other hand, the spark plug temperature is too high, there will be pre-detonation. The air-fuel mixture will start burning even before the spark ignition.
Does a spark plug use AC or DC?
Spark plugs receive high voltage current from the ignition coil, which uses the battery’s DC as its power supply.
So, in a way, the battery’s DC power is the source of power for the spark plug. Be it in a motorcycle or in a car.
But the electricity flow is not that straightforward though. The direct current from the battery is of low voltage (usually 12 volts). And spark plugs require around 15,000 to 20,000 volt current to ignite the engine.
For more details, here is our post on the flow of electricity in spark plugs.
Why do spark plugs get carbon buildup?
The primary cause for black carbon buildup on spark plugs is the engine burning a rich air-fuel mixture.
Another common reason is the spark plug is too cold and is operating at a lower temperature than required.
The only fix for carbon buildup is to replace the spark plug. Sure, you can clean the buildup and reuse the same spark plug, but we suggest against it.
In addition, you also need to identify the cause of the carbon buildup. Check the carburetor tuning, air filter, and spark plug type to identify the root cause and address it.
For a more in-depth view, check out our post on spark plug carbon buildup here.