How To Remove The Ignition On The Trimmer

Often, owners of gasoline braids are faced with the fact that ignition does not work on their equipment. In most cases, the problem is really in this node. To fix it, you need to adjust the ignition on the trimmer. But at the same time, it is not uncommon that the ignition coil is serviceable, and the breakdown must be sought elsewhere. The ignition system is designed identically on four-stroke and two-stroke internal combustion engines, therefore, troubleshooting of this unit is performed in a similar way. In addition, the equipment of different brands has almost the same construction of this most important component of the tool, which means that the adjustment process will be identical for the Soyuz or Foreman trimmers, as well as for Huter or samples of other brands.

Ignition on the trimmer. The principle of operation and possible malfunctions

If the owner of the lawn mowers wants to set the ignition system on their own, he should understand the principle of operation of this unit. In an internal combustion engine, it consists of a flywheel and a magneto (coil). In turn, the flywheel includes an impeller that performs the function of cooling the motor and a number of permanent magnets.

How To Remove The Ignition On The Trimmer

Operating principle

When the flywheel rotates, an electric current is generated in the magneto, creating a spark on the spark plug at the instant when magnets pass under the coil.

Typical malfunctions

Before starting to adjust the trimmer ignition, you need to cut off other probable causes of failure and make sure that the problem is really in this node. To do this, it is necessary to carry out a series of actions in the following sequence:

  • Inspect the ignition coil housing for damage and defects;
  • Make sure that all nodes and elements that conduct current, there are no pollution;
  • Check the integrity and insulation of the wiring, contacts, fastening strength, the presence of rust at the joints;
  • Inspect the candle cap, as it is regularly torn off from the high-voltage wire, and they try to restore it manually, and any unreliable connection reduces the power of the electric arc of the candle;
  • Check the candle, because the quality of modern gasoline very quickly disables this part, but there is another possible problem. The candle is wet;
  • Make sure the circuit breaker is working.

Eliminating all possible malfunctions, you can proceed to adjust the ignition of the coil.

When adjustment is needed

It is necessary to adjust the ignition system so that the fuel ignites in the combustion chamber at the right time.

If the flywheel is shifted on the shaft relative to its original position, the fuel ignites faster than the piston overcomes top dead center. As a result, the piston moves backward, and the crankshaft rotates in the opposite direction. You can determine the early ignition of a fuel by a broken launch cord, a broken starter assembly, or other breakdowns..

Sometimes ignition is late. The piston compresses the non-flammable fuel, and then goes down, and only then a spark forms. As a result, the engine either does not work, or its power decreases, and the speed rises much more slowly.

Typically, a flywheel with magnets is installed in an ideal position, precisely coordinated with the piston, and is carefully fixed to avoid bias. This suggests that incorrect part installation is not possible. But if the flywheel shift is a confirmed fact, then it is a malfunction or an accident. In this way, no ignition timing required, since problems with early or late ignition of the fuel are very rare.

Magneto Diagnostics

Magneto is a key component in engine ignition systems. This is a core coil that is surrounded by the primary and then the secondary windings. If this part is faulty, there is no spark on the spark plug, and the fuel does not ignite.

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First way

Check the performance of magneto using a tester. To do this, you must perform this sequence of actions.

  1. Correctly configure the tester: use the resistance measurement function and set 200 Ohms to take measurements of the primary winding.
  2. Direct the first electrode of the measuring device to the magneto “mass”, and the second to the output contact. If the primary winding is working, the indicators should be from 0.4 to 2 ohms.
  3. Set the tester switch to 20 Com to diagnose the secondary winding. Then direct the first probe into the cap of the candle, and the second. To the “mass”. If everything is in order, the indicators will vary from 4 to 6 Kom, depending on the trimmer model, whether it be the Patriot 547, Husquarna 128 r or a different brand of equipment. If the circuit is broken, an infinity value will appear on the tester screen. And if a short circuit occurs, the display will show zero.

Second way

If you can’t use the tester, there is another way to conduct a test. It is important not to touch the cylinder with the electrode, otherwise the coil will be damaged.

  1. It is necessary to remove the cap from the spark plug. Do not unscrew the candle, as this will allow to keep the compression.
  2. Then you need to pick up the nail with the hat removed and firmly insert it into the cap.
  3. Next, the cap with the nail should be firmly tied to the cylinder with a dielectric. In this case, the electrode should be at a distance of 5.5-7 mm from the cylinder body, but not touch the mass.
  4. Then the starter needs to perform an imitation of starting the engine with the ignition button on. In this case, it is necessary to carefully monitor whether a spark appears, and try to determine its color.

There is one important point that must be considered when diagnosing: unheated magneto in any state can form a powerful spark. However if it is faulty, then, having warmed up, it stops creating current, and the trimmer will not start. Later, after cooling down, the coil returns to the operating level again, the tiller turns on and for some time runs at idle or under load until the magneto temperature rises again. In this case, the part must be replaced with a new one.

Ignition Adjustment Procedure

Setting up the ignition system is simple and identical on different trimmers, be it Stihl FS55, AL-KO BC 4125 or another lawn mowing machine. First, you need to remove the casing from the engine, having previously unscrewed the fastening fixing it. This disassembly step may differ on different lawn mowing models (described below). Next, you need to partially unscrew the fastener fixing the magneto with a screwdriver and turn the handwheel so that the magnets are in the upper part.

To make the optimum clearance between the coil and magneto, you must use a special template. Buying it for a single use is impractical, therefore, as an alternative, you can use a business card or a small pocket calendar, as well as A4 paper sheet folded in four. Also, a strip cut from a plastic bottle or other improvised materials having the required thickness is suitable. The optimum distance is usually indicated in the user manual. The selected item must be placed between the magnets and the coil.

Then the coil will be attracted to the flywheel by a magnetic field. While holding the magneto in this position, you need to tighten the fixture fixing it, and then pull out the business card. After that, you need to scroll the flywheel several times to make sure that it does not touch the coil at all. The process is over. The ignition on the lawn mowing is set. In more detail, the process of adjusting the trim ignition system can be studied on the Internet, where there are manys dedicated to this topic.

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Features of adjustment on different models of trimmers

The ignition system is arranged in a similar way on the technology of various brands, so the process of its adjustment will look the same. The differences, if any, are insignificant. Basically they related to disassembling equipment. For example, removing the casing from the engine on different trimmers is performed with some differences. So, on Patriot devices, you first need to unscrew the bolts and disconnect the air filter housing with a slotted screwdriver. After that, the plastic cover will be very easy to remove. A detailed diagram and trimmer device for a specific model is usually shown in the tool manual.

So, you can do the ignition for a gas trimmer with your own hands. This process is simple if you know the correct procedure. But first you need to eliminate the possible malfunctions of other components and parts, for example, spark plugs or magnetos, which can be the reason for the lack of starting the engine of the lawn mowers. However, when analyzing equipment of different brands, it is necessary to take into account the likely differences in design, which are described in detail in the user manual.

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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.

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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.