Ignition on a walk-behind tractor: characteristics and adjustment

The motoblock is now a fairly widespread technique. This article describes the ignition system, how to set it up and what problems may arise during the operation of the device.

The ignition system is one of the most important units of the walk-behind tractor mechanism, its purpose is to create a spark, which is necessary for the combustion of fuel. The simplicity of the design of this system allows users to successfully try to repair or adjust it themselves.

Typically, an ignition system consists of a coil connected to the mains supply, a spark plug and a magneto. When voltage is applied between the spark plug and the magnetic shoe, a spark is formed, which ignites the fuel in the engine combustion chamber.

If your walk-behind tractor does not start well, you need to pull the starter cord for a long time or the engine responds with a delay, most often you just need to set the ignition correctly. The procedure is described in the instruction manual of the device. But what to do if it is not at hand, and you don’t remember where you put this useful brochure?

Follow the guidelines below.

Close the spark plug with a square, press its body against the cylinder head by turning this element of the ignition system in the opposite direction from the hole in the end of the cylinder. Turn the crankshaft. You can do this by yanking the starter cord. As a result, a bluish spark should slip between the electrodes. If you do not wait for the spark to appear, check the gap between the stater and flywheel magneto. This indicator should be equal to 0.1 - 0.15 mm. If the gap does not correspond to the specified value, it needs to be adjusted.

You can try setting the ignition by ear, especially if yours is quite thin. This method is also called contactless. To do this, start the engine, slightly loosen the distributor. Slowly turn the breaker in two directions. At the maximum power and number of revolutions, fix the structure that determines the moment of sparking, listen. You should hear a clicking sound when you turn the breaker. After that, tighten the distributor mount.

Warm up the motor, connect the stroboscope to the power circuit of the motoblock device. Place the sound sensor on the high voltage wire from one of the engine cylinders. Dismantle the vacuum tube and plug it. The direction of the light emitted by the stroboscope must be towards the pulley. Run the engine idle, turn the distributor. After ensuring that the direction of the pulley mark coincides with the mark on the device cover, fix it. Tighten the breaker nut.

To prevent the occurrence of malfunctions in the ignition system try to follow simple recommendations:

• do not work on a walk-behind tractor if the weather is bad outside - rains, dampness, frost, or sudden changes in humidity and temperature conditions are expected;
• if you smell an unpleasant smell of burning plastic, do not turn on the unit;
• protect important parts of the mechanism from water penetration;
• replace the spark plugs about once every 90 days; if you actively use the device, this period can and should be shortened;

• the oil used for the engine must be of high quality and of a brand suitable for the given model, otherwise the spark plug will be constantly filled with fuel;
• carry out regular inspections of the ignition system, gears, in order to prevent the use of the unit with broken cables, and other malfunctions;
• when the motor heats up, try to reduce the load on the device, so you will protect the mechanism from accelerated wear;
• when you do not use the walk-behind tractor in winter, put it in a dry and rather warm room under lock and key in order to prevent hypothermia of the device.

The main problem is the lack of a spark... Most likely, the reason is in the candle - either carbon deposits have formed on it, or it is faulty. Unscrew it and carefully inspect the electrodes. If there is carbon deposits formed by filling with gasoline, in addition to cleaning the spark plug, it is necessary to check the fuel supply system, there may be leaks there. If there is no spark, you need to clean the spark plug. A good way out is to heat it over the switched on gas burner, scraping the frozen drips of the fuel mixture from its surface.

After cleaning the spark plug, test it for proper functioning. To do this, put a cap on the top of the part and bring it, holding it in one hand, to the motor block of the walk-behind tractor at a distance of about 1 mm. Try to start the engine with your free hand.

If not, check the electrode gap. Try to put a razor blade in there, and in case the electrodes grip it tightly, the distance is optimal. If there is a loose swing of the blade, the position of the electrodes must be corrected. To do this, lightly tap the back of the center piece with a screwdriver. When the electrodes are in optimum position, try starting the engine again. If the spark does not appear, test the magneto for serviceability.

Possible other problems with the ignition system:

• weakness or lack of spark;
• the feeling of an unpleasant smell of burnt plastic in the part of the mechanism where the ignition coil is located;
• crackle when starting the engine.

To do this, after unscrewing the mounting bolts, remove the upper part of the ignition casing. Then disconnect the power cord, pry the coil element and pull it out. Carefully inspect the appearance of the part - the presence of black spots indicates that the current did not flow to the candle, but melted the coil winding. This situation is especially relevant for motoblocks with contactless ignition.

The reason for this malfunction is in poor-quality contacts on the high voltage cable. It is required to strip or completely replace the wires... Devices with an electronic ignition system have an automatic fuse that cuts off the power in the event of a malfunction. If your car has any other ignition system, the cable will have to be disconnected with your own hands. If a spark pierces when turned on, check the tip of the spark plug, most likely it is dirty.

How to adjust the ignition on the walk-behind tractor, see below.