How to properly set the ignition on the trimmer: adjusting the gap between the magneto and the flywheel
Gasoline trimmers are used as two-stroke internal combustion engines (ICE), and four-stroke. But the ignition system in them is no different, therefore, the repair and adjustment of this fuel ignition system will be the same for different types of internal combustion engines.
How the trimmer ignition system works
The ignition system of a two-stroke internal combustion engine consists of 2 elements: flywheel and coil (the magnet). The figure below shows, what they look like.
There is an impeller on the flywheel, which acts as a fan to cool the engine. Also on one side of the flywheel are permanent magnets, the figure is shown by an arrow.
When the flywheel rotates, an electric current is produced in the coil, which serves to create a spark on the spark plug. The spark appears in an instant, when the magnets are directly under the magnet.
Why do you need ignition control?
In some cases, when the engine does not start, ignition control required. Of course, first you need to check the condition of the spark plug and high voltage cable with the cap.
You need to adjust the ignition on a two-stroke engine, to ensure timely ignition of fuel in the combustion chamber of the engine. Below is a diagram, from which it is possible to understand the principle of operation of the internal combustion engine.
The spark in the spark plug should appear when the fuel is compressed by the piston, when it barely reaches the top dead center (TDC). When the piston passes TDC, there is an outbreak of fuel mixture, as a result of which the piston under the action of energy of explosion goes down.
So, if for any reason (this is mainly due to the shift of the flywheel on the shaft relative to its initial position) fuel ignition occurs earlier, than the piston will pass TDC, then he comes back, and the crankshaft scrolls in the opposite direction. This movement can damage the starter assembly, break the start cord, etc.. In this case, there is an early ignition of the fuel.
There may also be a late ignition on the Trimmer: piston after fuel compression, which did not ignite, goes down, and at that moment a spark appears. In this case, the engine will either not start, or significantly lose power and slow gaining speed.
But such problems with early or late inflammation on two-stroke internal combustion engines are quite rare, as the flywheel with magnets is already installed in the correct position, which is perfectly synchronized with the movement of the piston. Besides, the flywheel is fixed on a shaft by means of a key and a nut. Therefore, incorrect installation of the part is excluded.
Mainly, ignition control is to set the correct gap between the magneto and the flywheel.
How to check the serviceability of the magneto
The magneto is the main part in the ignition system of the engine and is a coil with primary and secondary windings, located around the core. Often, due to a malfunction of the magneto, the spark on the spark plug disappears, and fuel ignition does not occur. To check the coil, you need to use a tester, and follow these steps.
- On the testers, switching to resistance measurement mode, you need to set 200 Ohm. This will check the primary winding.
- Connect one tester electrode to the ground of the coil, and the other - to the contact, coming out of the magneto. Normal, resistance must be from 0,4 to 2 Ohm.
- To check the secondary winding, you will need to set the device switch to 20 lump. Further, one probe of the device is inserted into the candle holder, and the second - joins the "mass". Normal, resistance values should be in the range of 4-6 to whom and above (depends on the model).
If the circuit breaks, the device will show infinity, and in case of short circuit - 0 (zero).
If you do not have a tester, then you can use the following method, showing great accuracy, so that the electrode does not touch the cylinder, otherwise the coil will burn out.
- Remove the cap from the candle. You do not need to unscrew the candle, to keep compression.
- It is necessary to insert a nail without a hat into the cap. The nail should be of this diameter, to hold well in the cap.
- Tie the nail cap to the cylinder, using a dielectric, so, so that the gap between the electrode and the cylinder body was within 5,5 to 7 mm (but in no case did not touch the "mass").
- Use the starter to simulate starting the engine several times. The ignition button must be on.
- Watch it, whether a spark appears, and what color it has.
Normal, the spark must be strong, white or have a blue tint. If the spark is weak, and its color is orange or yellow - this indicates a faulty magnet.
That fact must also be taken into account, that sometimes a magneto in the cold state can give a good spark. But after heating due to internal faults ceases to produce electricity. As soon as the coil cools down, the trimmer restarts and runs for some time, until the magneto heats up again. This coil must be replaced.
Sometimes a similar problem with heating can be caused by a spark plug, even if the coil is working, so you need to check both parts.
Ignition control algorithm
Ignition on the Trimmer is easily regulated.
- Remove the cover from the engine, unscrewing all the retaining bolts. Example, on petrol mowers Patriot (Patriot) PT 2540, to remove the cover, you need to unscrew the air filter housing, and remove it from the latches with a flat screwdriver. After that the plastic case will be easily removed.
- Unscrew with a screwdriver 2 bolts (it is not necessary to unscrew completely), which hold the magneto.
- Turn the flywheel this way, so that the magnets were on top.
- Further, to correctly set the best gap between the flywheel and the coil, you can use a regular business card or pocket calendar. If not, you have nothing else at hand, then, to adjust the ignition, you can use a sheet of A4 paper, turning it 2 times (as a result, you will get a thickness of 4 list). This thickness will be enough, to get the optimal clearance and adjust the ignition. Insert a business card or paper between the spool and the magnets.
- The magnetic field will pull the coil to the flywheel. Holding the magneto with your fingers in this position, tighten the retaining bolts.
- Remove the business card. After that the ignition on the Trimmer will be adjusted.
