Gap on a chainsaw spark plug: is it dangerous and how to put everything back in place

Beginning chainsaw users often ask the question: “How to check the ignition on a chainsaw?”, without much explanation. Why they need this and what they want to do with further information is unclear.

Ignition of a chainsaw is a complex system, and incorrect clearance can lead to deformation of the entire device. If your saw does not start, then the ignition system is immediately checked. Our short article will tell you how to check the ignition coil on a chainsaw. Make yourself comfortable, we're starting!

The design of the chainsaw ignition circuit: what parts does it consist of?

Before diagnosing, servicing or fully repairing the entire chainsaw mechanism, you need to know what to repair and look for. In our article we will deal with only a small element - checking the ignition coil of a chainsaw. Let's look at what parts the system consists of:

• A magneto for a chainsaw (to put it simply, a coil) is the main component of the system from which the electrical impulse comes.
• The flywheel is an aluminum part with magnetic soldering. Possibly with spraying. Generates the spark itself by acting on the ignition coil. Also, in addition to creating a spark to start the engine, the flywheel cools the system and increases the strength of another part - the crankshaft.
• High voltage wire. It is also called an armored cable. This is a type of wire with good insulating windings. Transmits impulse from the coil to the spark plug.
• The spark plug is the last element in the ignition system. It consists of two parts: the first half is located in the internal combustion engine, and the second is outside (it is powered by a high-voltage wire). The spark plug is screwed tightly into a special hole, completely isolated from the motor housing. With the help of a candle, the necessary spark is formed, igniting the fuel in the combustion chamber.
• Starter (starting device) is an auxiliary element for working with the contacts of the ignition coil. Allows you to control the engine and stop it in time when the work is finished.

The chainsaw's ignition system acts like a regular generator. A flywheel with magnets adjusted to different poles rotates. They create an electromagnetic field, which is then converted into a current charge.

The coil “excites” the electric current, transmitting the impulse to the transformer. It is then converted to high voltage and supplied to the spark plug. And already there a spark appears, igniting the fuel in the engine chamber. The chainsaw starts.

What does the gap on a chainsaw spark plug affect?

Gasoline internal combustion engines have an ignition that does not work if one of the structural elements fails. Whatever one may say, without the slightest detail the engine will not start. It’s not like with a TV: you slap the lid and everything works.

Even a small misfire or breakdown in a well-functioning system can cause a malfunction of the unit. The slightest carbon deposit on a candle is an example.

If the ignition coil gap is within normal limits and there are strong electrodes in the chainsaw, nothing may happen.But sometimes this is not enough to penetrate the dense mixture of the atmosphere at a long, uncharacteristic distance.

Also, a distance greater than necessary increases the energy output of the coil, reducing the spark fuse. The working mixture does not ignite when the starter moves. The result is that the engine either does not pick up speed or does not start at all. Next, we will talk about what is the normal gap on a chainsaw spark plug and how to correct the situation if you have them incorrectly set on the saw.

How to check the spark on a chainsaw and set it to the required value

Loads on a running engine constantly negatively affect the degree of fixation of all elements. There's nothing you can do about it. Therefore, diagnostics of the device are necessary from time to time.

One of the first problems in rare chainsaw diagnostics is a maladjustment of the ignition system, which requires the correct clearance between the ignition coil and the chainsaw flywheel.

The average value that must be maintained between the coil and the flywheel is up to 0.4 mm. The exact parameters are always indicated in the instructions or data sheet of the instrument. If there is no specific data, then set it somewhere around 0.3 mm - you can’t go wrong.

To set the correct value, we need several tools:

• Screwdriver with a set of attachments (bits).
• A spacer made of paper - we will use it to adjust the working gap.
• Thread locker. If it is not there, it is not critical. It will work without it for the first time, but then you will have to configure the system more often than usual.

First we need to remove the left side housing piece. All ignition elements are located under it.

Use a screwdriver to loosen the coil screws. It is better if you unscrew them completely and pour thread lock into the holes. Then not a single screw will accidentally come loose or get lost.

We install a paper spacer between the flywheel and the module. It could even be cigarette paper or a piece of plastic bottle.

We unfold the flywheel with magnets so that they touch the coil contacts. There is already a spacer there. The effect of magnetizing the element should be created. Then we tighten the screws back, a little stronger than average (do not over-tighten, so as not to break the threaded connections).

Remove the spacer and watch how the flywheel moves. It should not come into contact with the coil and should spin smoothly.

That's all. All that remains is to find out how to check the coil on a chainsaw. If it is working properly, then a spark appears already at the first movement of the starter. Let's see how this works in practice.

How to check magneto and spark plug on chainsaws

It happens that the problem itself is not detected. Or you have already done all the work and want to test the result before adding fuel to the chainsaw and working directly. So, we check the ignition coil of the chainsaw. Here are several stages of the test:

Measuring resistance using a multimeter. To perform the procedure correctly, you need to know the standard parameter for your tool - it is in the instructions or in the data sheet.

Due to the fact that the system uses semiconductor parts, the continuity test system may indicate an open circuit. Don't worry, everything is fine. If the spark plug is faulty, the multitool will show a positive result (the coil did not provide resistance).

You can also check the spark with a special device. Such a device is placed on a circuit break. It is located between the wire and the spark plug. The verification indicators are displayed on the board. The device is situational, and you are unlikely to find it in a store. But service centers and service stations are full of such material.You can ask a friend to check the spark plug for serviceability.

Do the ignition yourself. To do this, the candle is turned out and placed with the body against the cylinder. Next, pull the starter. If a spark appears, at least minimally, everything works. But if there is a drawback in the example, the flywheel spins faster and the results may be distorted. This is because the candle is positioned incorrectly during the test.

If the above options did not give any results or there is no tool at hand at all, then try doing this:

• Remove the cap from the candle and insert a nail or wire at a distance of up to 1 cm from the cylinder. Carry out the operation extremely carefully so as not to damage the parts.
• Start the tool and observe if there is a spark while the starter is running. If everything works well, the spark is strong and bright blue.

This method is an extreme way out of the situation. It is very dangerous, so you need to follow a few rules:

• You cannot remove the candle completely. This will cause the flywheel to move faster, and this is an abnormal mode of operation of the motor - you will not get the correct result.
• A parameter of 1 cm is average. The metal element must be positioned at the optimal compression distance and fuel mixture characteristics. For all information about this, see the instructions for the device.

It happens that a chainsaw does not start due to a lack of spark at the electrodes themselves. Although less common, this option exists.

How to check here? It's simple: we turn the spark plug out and put the armor wire on it. We try to ensure the most reliable contact of the ignition housing with the cylinder. Then we pull the starter and start the engine.

In this case, the spark should be clearly visible.If there is gasoline in the tank, but the spark never arrives, there is a break or a faulty part somewhere in the system. Check the magneto for continuity.

After all the procedures, the engine should work. If you have any questions or suggestions, ask in the comments below this article. That's all for today! See you!