Trimmer Clearance Between Coil

Trimmer Clearance Between Coil

ICE engines are installed not only on cars or motorcycles. They are widely used in various tools, for example, such as a chainsaw or trimmer. In case of their malfunction, poor start-up, it is often enough to set the correct clearance between the flywheel and the ignition coil.

About the chainsaw and its inoperability

Chainsaw – the installation itself is not so complicated. But to have the smallest initial knowledge is extremely important in order to find and eliminate any defect.

Modern electronics has progressed so much that it revolutionized the world of instruments. Saws of our days are light and powerful at the same time, equipped with electronic ignition systems ESZ.

Not so long ago, the ignition systems of saws were cam. This carried a lot of shortcomings: severity, complexity, high cost and much more. And the main drawback of the archaic ignition system is the difficulty of the plant. Some systems of model saws generally could not produce a spark sufficient to flash at the crankshaft speed.

Modern systems are almost faultless. The saw models are light and durable, the reel is made more professionally and serves its life almost without a hitch. However, there are problems, but in most cases they can be fixed on their own.

Consider the main types of chainsaw malfunctions associated with the flywheel and the ignition system.

As a rule, the most common ailment of modern chainsaws implies the absence of a supply spark. The same directly depends on the shift of the lumen (gap) between the woman and the flywheel.

Common installation failures are always associated with the internal combustion engine. Problems arise in the fuel ignition system, the fuel intake module, in the internal elements of the engine itself.

As for the other components of the chainsaw, malfunctions there arise, as a rule, due to failures of the brake mechanism, poor lubrication, etc.

If the startup difficulties are associated with the engine, then most often the following symptoms are observed:

  • The motor does not develop the necessary power;
  • Does not start at all;
  • It starts, but quickly stalls;
  • Functioning intermittently.

As always, experts recommend identifying malfunctions as an exception. In other words, you need to go through the chain, diagnosing each node, each link.

Ignition module

The failure of the SZ chainsaw is the most common reason why the tool engine does not start. It is recommended in most cases to start troubleshooting from here.

Here’s what to do:

  • First of all, carefully check the spark plug by carefully removing the armored wire from the head and unscrewing the spark plug from the socket using a special key;
  • The second is checking the spark supply with the help of the jerking of the starter when the cap of the armored wire is put on the candle;
  • Clearance check is the main topic of our article (more details below).

So, malfunction of the spark plug will clearly indicate its sputum. A wet spark device for igniting the fuel-air mixture indicates that there is an excess of fuel in the system, the carburetor is incorrectly configured, or there are malfunctions in the SZ.

The candle is checked only after drying. That is, it must be thoroughly cleaned with a napkin, drained inside of the ICE, clogged up the supply, and then start the starter a couple of times so that the excess combustible mixture comes out.

Then the spark device is put in place, and everything is checked again.

In general, a spark device can tell a lot about the entire ignition system. If a black deposit is observed on the candle, then this indicates a violation in the communications of the supply of the gasoline mixture. Here, either the ratio of gasoline to oil was violated, or a carburetor retuning was required. In some cases, this also happens due to poor-quality oil.

A dirty candle is cleaned of black soot with a needle or some other sharp object. Then, the electrode is cleaned with sandpaper (null) until a metallic luster appears. The spark device returns to its place, everything is checked again.

The next step: verification of spark supply. The skirt of the spark device is brought to the cylinder, the starter starts. If a bluish spark slips at a distance of 2-3 mm, everything is fine. A spark distance of 0.5-1 mm is already considered as a malfunction. There may be no spark at all, and this is also a big problem. Perhaps this is a broken wire.

And now we come to the topic of our article. A chainsaw may not start due to a violation of the gap between the ignition and the flywheel magneto. This gap should be within 0.2 mm. It is checked very simply: a special gasket is placed between the flywheel and the crib. If it goes in normally, not too loose and tight, then the gap is normal.

The flywheel itself drank is round, and checking the gap with a conventional probe is not possible. It would be more qualified to set the gap according to the special template, but it is not always possible to acquire it. Yes, and not everyone can afford to buy a template that is not cheap, for a one-time use.

However, instead of a foreign template, you can use a cut out strip from a plastic container of 1-2 liters from under the juice.

A homemade template is put like this:

  • The ignition fixing bolts loosen;
  • There is a plate between the flywheel and the crib;
  • Bolts are tightened.

How to check magneto chainsaws

Magneto, Babin, module is an ignition coil. It may be completely irrelevant to instrument failures, and the reason for hiding is only in the gap or in another. But in some cases, it is she who becomes a violation factor.

To check the babin herself, one should also, as in the case described above, use by eliminating the components from the chain. Or in other words:

  • Visually assess the condition of the woman’s body for cracks and other visible defects;
  • Check the purity of current communications of various nodes and elements;
  • To diagnose the insulation and serviceability of the armored wiring, the reliability of fixing the mounts, the absence of rust, etc.
  • Visually assess the state of the cap of the spark device;
  • Checking the health of the candles;
  • Circuit breaker diagnostics, which is especially true for Chinese-made chainsaws.

Video: Trimmer Clearance Between Coil


Again, as in the case described above, certain items are excluded from this chain, thereby finding the cause of the problem.

The woman herself is explored like this.

  • The magneto resistance is measured. However, this option is not always applicable, since you must first know the resistance parameters. In addition, for the formation of the required explosive pulse, it is necessary to separate the indicators of various semiconductor elements. A sign of a problem, as a rule, is the ringing of the circuit through the BB wire and minus. It should show either "open circuit" or a lot of resistance.
  • The check can be done like this – use the device that checks for the presence of a spark. It is installed in an open circuit between the explosive wire of the woman and the candles. The disadvantage of this method is that the device is so very expensive, it is used mainly in serious repair services.
  • "Dedovsky" verification method, which will save on an expensive device. It is used at your own peril and risk when there are no other options. The verification method comes down to the fact that a cap is removed from the candle, a carnation is inserted into it. The candle re-inflates. The carnation should be located at a distance of 6-7 mm from the cylinder. The chainsaw starts up. The spark is being investigated: it should be bright blue, if not, then this is a sign of a woman’s problem.

The "grandfather" way of checking a woman has many drawbacks. First of all, this applies to the electrical nodes in the system, which can easily deteriorate. The distance between the cylinder and the stud may differ depending on the different models of the tool.

As for the magneto tuning, it comes down to the study of grooves on the flywheel. UZO for most of the current models of saws do not need to be regulated. But it is possible to determine its exposure only by the angle between the mark after the groove on the flywheel and the magnets mounted, again, on the flywheel.

Properly and accurately set the gap between the magneto and the flywheel – this is more important.

You should be aware that the Babin on chainsaw systems is installed in the fuselage of the fan near the flywheel. The coil, in contact with the flywheel magnetic field, produces energy for a spark.

Replacing the coil itself will be much more difficult, since the installation location is too inconvenient. The installation of a new bobbin should be carried out so that the base of the coil is at a distance of 1-1.5 mm above the flywheel magnets.

In some cases, it is also recommended to check the crankshaft bearing for play.

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On gas trimmers, both two-stroke internal combustion engines (ICE) and four-stroke are used. But the ignition system in them is no different from each other, so the repair and adjustment of this fuel ignition system will be the same for different types of ICE.

How the trim system works

The ignition system of a two-stroke ICE consists of 2 elements: a flywheel and a coil (magneto). The image below shows how they look.

An impeller is located on the flywheel, which acts as a fan to cool the engine. Also on one side of the flywheel are permanent magnets, shown in the figure by an arrow.

When the flywheel rotates, an electric current is generated in the coil, which serves to produce a spark on the spark plug. A spark appears when the magnets are directly below the magneto.

Why do I need ignition adjustment

In some cases, when the engine does not start, ignition adjustment will be required. Of course, first you need to check the serviceability of the candle and high-voltage cable with a cap.

Ignition control on a two-stroke engine is necessary in order to ensure timely ignition of fuel in the engine combustion chamber. Below is a diagram from which you can understand the principle of the internal combustion engine.

A spark in the candle should appear at the moment of compression of the fuel by the piston, when it does not reach the top dead center (TDC) just a little. When the piston passes TDC, the fuel mixture ignites, as a result of which the piston goes down under the action of the explosion energy.

Therefore, if for some reason (mainly due to the displacement of the flywheel on the shaft relative to its initial position), the fuel ignites before the piston passes TDC, then it goes back and the crankshaft scrolls in the opposite direction. This movement can damage the starter assembly, cut off the starter cord, etc. In this case occurs early fuel ignition.

May also be late ignition on the trimmer: the piston after compression of the fuel, which did not ignite, goes down, and at this moment a spark appears. In this case, the engine will either not start, or it will significantly lose power and will not gain momentum well.

But such problems with early or late ignition on two-stroke ICEs are quite rare, since the flywheel with magnets is already installed in the correct position, which is perfectly synchronized with the movement of the piston. In addition, the flywheel is fixed to the shaft with a dowel and nut. Therefore, incorrect installation of the part is excluded.

How to check the health of magneto

Magneto is the main part in the engine ignition system and is a coil with primary and secondary windings located around the core. Often, due to a magneto malfunction, a spark disappears on the spark plug, and ignition of the fuel does not occur. To check the coil, you will need to use a tester, and perform the following steps.

  1. On the tester, going into resistance measurement mode, you need to set 200 Ohms. In this way, the primary winding will be checked.
  2. Connect one tester electrode to the “mass” of the coil, and the second to the contact coming out of the magneto. Normally, the resistance should be between 0.4 and 2 ohms.
  3. To check the secondary winding, you will need to set the switch of the device to 20 com. Further, one probe of the device is inserted into the cap of the candle, and the second is connected to the “mass”. Normally, resistance indicators should be in the range from 4-6 kom and above (depending on the model).

If you don’t have a tester, then you can use the following method, with great care so that the electrode does not touch the cylinder, otherwise the coil will burn out.

  1. Remove the cap from the candle. You do not need to twist the candle to maintain compression.
  2. Insert a nail without a cap into the cap. The nail should be of such a diameter that it holds well in the cap.
  3. Tie the cap with the nail to the cylinder using a dielectric so that the gap between the electrode and the cylinder body is between 5.5 and 7 mm (but by no means touches the “mass”).
  4. Using a starter, simulate the engine starting several times. The ignition button must be on.
  5. Observe whether the spark appears and what color it has.

Normally, the spark should be strong, white or have a bluish tint. If the spark is weak, and its color is orange or yellow – this indicates a faulty magneto.

It should also be borne in mind that sometimes a cold magneto can produce a good spark. But after heating due to internal malfunctions, it ceases to produce current. As soon as the coil cools down, the trimmer starts again and works for a while until the magneto is again heated. Such a coil must be replaced.

Ignition Algorithm

Ignition on the trimmer is fairly easy to adjust.

    Remove the casing from the engine by unscrewing all the bolts holding it. For example, on the Patriot (Patriot) PT 2540 lawn mower, to remove the casing, you will need to unscrew the air filter housing and remove it from the latches with a flat screwdriver. After that, the plastic case can be easily removed.

  • Using a screwdriver, unscrew the 2 bolts (it is not necessary to completely unscrew) holding the magneto.
  • Turn the handwheel so that the magnets are at the top.
  • Further, to correctly set the best clearance between the flywheel and the coil, you can use the usual business card or pocket calendar. If you don’t have either one at hand, then to set the ignition, you can use a sheet of A4 paper, folding it 2 times (in the end, you will get a thickness of 4 sheets). This thickness will be enough to get the optimal clearance and adjust the ignition. Insert a business card or paper between the spool and magnets.
  • A magnetic field will pull the coil to the flywheel. Holding magneto with your fingers in this position, tighten the bolts holding it.
  • Remove the business card. After that, the ignition on the trimmer will be adjusted.