Stihl 180 Spark Plug Gap

Electric chainsaw spark plugs for two-stroke engines are used on chainsaws. Similar or completely similar candles work on lawn mowers, gas generators, small motor pumps, and other devices with a small push-pull ICE.

Stihl 180 Spark Plug Gap

Clearance and other candle parameters

Key parameters that a buyer needs to know:

  • the diameter of the thread that is screwed into the cylinder;
  • the length of this thread (in vernacular skirt or shirt);
  • the gap between the central current-carrying core and the side electrode (mass), between which a spark is formed.

The exact clearance for each model of the chainsaw is specified in the Operating Instructions. For different models, it varies in the approximate range of 0.45. 0.55 mm.

There are other options. For example, a thread pitch. But it is standardized for all candles of this type (M10x1) and do not think about it when buying.

There are voltage parameters on the candle. They are huge, from 10 to 20 thousand volts and above. They are taken into account by manufacturers for the calculation of insulators, etc. The user does not need to know the exact voltage.

It is important to remember that when you touch the spark plug contact or the spark plug electrode when the starter is jerked, you can get a very noticeable electric shock. He cannot kill, because at high voltage, the ignition current has a small force, which is measured in microamps. However, the beats are very noticeable.

Candle producers: a review of the best

In addition, well-known manufacturers of chainsaws themselves produce candles.

Quality spark plugs are produced by the following manufacturers:

These are the most famous brands, but the list is incomplete, many manufacturers of chainsaws themselves produce spark plugs.

Therefore, when the question arises of what to choose: a cheap option or an expensive one, for example, Husqvarna or Champion (they are approximately equal in price), it is better to opt for quality.

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What is the resource of candles

Spark plugs are consumables, that is, they obviously have a shorter service life than a chainsaw. It is technologically customary to consider the service life of the spark plugs for chainsaws. 100 hours. After this period it is recommended to change it. In practice, this period can be significantly higher or lower. Above under the following conditions:

  • when working, high-quality gasoline and oil are used;
  • there was no critical overheating of the engine and overheating of the spark plug;
  • the gap is correctly set, normal electric arc (spark);
  • preventive measures have been taken: “null” cleaned the contact between the central and side electrodes, the contamination inside the candle was removed.

On the contrary, reduce the life of the candle poor-quality fuel, over-heating, pollution. An incorrect gap leads to the fact that too long or short arc accelerates the burning of the electrodes (the effect of electric welding).

How to assess the condition of the candle visually

The first sign of a candle failure can be detected immediately, even without twisting it from the cylinder. a dark belt on a white insulator immediately above the turnkey iron hexagon. This means that the candle has lost its tightness, and the combustion products make their way to the surface. Such a candle must be replaced immediately and without options.

Video: Stihl 180 Spark Plug Gap


Tanning score

It is generally accepted that during normal operation of the entire ICE and candles, it should have a coffee-chocolate color deposit. However, this is not always the case. A deposit of this color appears only at high temperatures and after a certain time of continuous operation.

For example, if you cut thick logs at high speeds for about an hour, then the candle may be soot exactly this color. And vice versa, the chainsaw will start quite normally and work for some time at low speeds.

If the saw has died out for some reason, you can turn out the candle and see that it is slightly wet from non-burning fuel and dark. However, this is by no means an indicator that the candle is out of order.

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Depressurization candles

In addition to igniting the fuel, the spark plug performs another passive function. it ensures the tightness of the combustion chamber, without which working compression and generally normal engine operation are impossible. Depressurization is indicated by the appearance of a dark girdle on the insulator, as mentioned above.

Depressurization occurs exclusively during mechanical failure. That is, the candle insulator could crack or even fall apart. A prerequisite for this can be both manufacturing defects and extreme operation with severe overheating and sudden cooling. For example, when working in severe frost, the candle first becomes hot. The engine is turned off, the candle cools sharply. If the cycle repeats, the insulator may not withstand.

The same can happen when water gets in or when hit.

Carbon deposit between the electrodes

Nagar is formed for the following reasons:

  • fireproof impurities in low-quality gasoline;
  • unwanted components in low-quality (fake) oil;
  • dust entering through a low-quality air filter;
  • low combustion temperature during prolonged operation of an unheated engine at idle or in frost;
  • exhaust exhaust problems.

In short, the poor performance of a candle cannot be the cause of soot. On the contrary, soot can cause problems in the operation of the candle. If it forms between the electrodes, where a spark occurs, it can work as an insulating gasket and the spark disappears. That is why it is recommended that you carefully clean the contact in this place with an emery cloth. zeroing after 50-70 hours or when soot appears.

Another weak point of the candles is the internal circumferential clearance between the insulator and the iron body that carries the “minus”. If it is clogged with conductive dirt or soot, then the closure of the plus and minus may occur not between the electrodes, but inside the candle body.

About the formation of soot between the electrodes of the candle and the connection of the undesirable result with the quality of the fuel mixture is described in the video:

Central electrode break

Among normal candles, such a defect is extremely rare, that is, almost never. It means that the candle just fell apart, but they made it unknown where and how.

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The central electrode is a solid copper rod filled with ceramic insulator. During the operation of the chainsaw there are no loads and forces that can somehow stretch or press on this rod. That is why we must try hard to make the spark plug so that its central electrode breaks.

We recommend reading an interesting article about what to do when it pours a candle on a chainsaw and what to do.

How to choose the right candle for a chainsaw

Despite the unification and interchangeability within the framework of the matching parameters of the candles of even different brands, this is a very important point.

The most important thing is that the length of the thread (skirt) is exactly the same as that of a native candle.

  1. If you screw in a long-threaded candle, it can reach the piston and it will be damaged even if you try to start the engine. The candle will decrease the clearance.
  2. If the thread is too short, the fuel mixture will not ignite in the combustion chamber, but in the threaded channel of the cylinder. A chainsaw may even work for some time, but soon this channel will be completely closed with soot.

In the operating instructions for each chainsaw it is precisely indicated which candle is used. According to these data, and should choose a new one.

If the instruction is lost or a chainsaw is bought from a hand, a candle is picked up, informing the seller of the model of the chainsaw. But there is a risk of finding a poorly suitable analogue.

The third option is selection by size, marking and appearance of the native candle.

Even if the candle is working properly, it is advisable to have a spare. This is for diagnostic purposes. If the chainsaw stalls, the first thing they do is change the candle to see if it has a cause.

This is necessary in order not to stop working with a chainsaw if a single candle fails unexpectedly and at the most inopportune moment.