In detail: petrol trimmer mtd 790 DIY repair from a real master for the site my.housecope.com.
Modern technologies and equipment make it possible to produce the best and optimal technical solutions that become effective assistants in the arrangement of a summer cottage or a personal plot. The green lawn and other plantings can grow rapidly, a petrol cutter is used to tidy up the local area and mow the lawns, which is also called a brushcutter or trimmer, a petrol mower.
Traditional braids are inconvenient and unsafe to use, require a significant investment of time and effort, which will help save gas mowers, combining functionality and practicality in their design. In the photo of the petrol brush, you can see various high-tech devices, which are inherent in a set of operational characteristics, including such parameters as increased productivity and a long service life.
A convenient and reliable trimmer is a technical device consisting of individual mechanisms, parts and elements that can wear out, become unusable and damaged during intensive use.
Even with regular technical inspection, maintenance procedures and careful storage, such devices and their individual parts require repair and even replacement, all repair procedures can be performed independently.
Brief content of the article:
The easiest way is to give the petrol cutter for repairs, having allocated a certain amount of funds from the family budget, prompt and high-quality repair with your own hands is no less simple and convenient if you want to understand the design of the petrol cutter and fix all the problems.
Video (click to play).
The mass and piece production of trimmers is based on the use of generally accepted technology, a typical design scheme consists of certain elements and parts, it is important to know them when carrying out independent repair work:
top part. The basis of the entire structure, where all important elements are collected, such as a starter, a carburetor and a petrol cutter engine;
middle part. A hollow rod, inside it is a cable that connects the motor and the gearbox, which drives the cutting line. In this part, there are fasteners for distributing the weight of the entire structure and a belt for fixing the trimmer on the belt of a person using the trimmer for its intended purpose;
Bottom part. It houses the gearbox and cutting elements, which are hidden under a practical cover to protect the user. The casing provides an increased level of safety, preventing large fractions of debris, stones and glass from entering a person while working with a petrol cutter.
Knowing exactly the internal structure and the principle of operation of the trimmer, you can independently carry out repair measures for the structure or replace individual components that have become unusable, using the repair instructions.
The most common and common failures of the unit that need to be corrected on their own include the following problems:
engine malfunction, due to which the brushcutter does not start and does not work;
increased vibration of the brushcutter bar, which complicates its intended use;
increased overheating of the gearbox, its accelerated heating during operation;
slow and weak functioning of the cutting line at insufficient speed;
clogging of the starter grille, causing overheating of the engine and its refusal to work;
fast and frequent clogging of the carburetor due to the use of low-quality fuel;
clogging of the air filter due to non-observance of the measures for the care of the device.
All these problems can lead to the fact that the device will lose its working capacity. Before ordering the necessary spare parts for the mowing, a visual inspection and diagnostics of the device should be carried out.
Particular attention should be paid to individual spare parts and units of the device, to check them you do not have to contact a professional master, a set of diagnostic measures will help you to identify the consequence of a loss of performance with your own hands.
If the trimmer motor does not start or stalls immediately after starting, when the gearbox overheats or during the operation of the device, extraneous noises are heard and vibration is clearly felt, it is important to visually inspect and identify a non-working unit.
To optimize the preparatory measures before repairs, you should carry out a simple diagnosis and check step by step:
the presence of fuel in the tank and lubrication in the main units;
serviceability of the spark plug and its performance;
the cleanliness of the fuel and air filter of the brushcutter;
clogging of the outlet channel and breather of the device;
the quality of the fuels and lubricants used.
To determine the functional efficiency of the petrol-cutter's ignition, it is necessary to determine whether the spark plug is working by testing the appearance of a spark when it comes into contact with the body of the functional device.
The spark plug itself can be replaced with a new one, having previously dried the candle channel, if necessary, the old element is also dried, cleaned with special devices and returned to its place.
In the process of inspecting the carburetor, it is worth paying attention to the possible leakage of the fuel used; to identify problems with the carburetor, the following measures must be taken:
purging the fuel hose to eliminate possible blockage of the element;
checking and replacing the gasket between the engine and the carburetor;
determination of tightness and maintenance of constant pressure in the unit.
If necessary, you can personally disassemble and thoroughly clean the unit using gasoline, the jet and channels are cleaned using compressed air.
The gearbox transmits torque from the motor shaft to the cutting tool, its gears during operation must be absolutely clean and always lubricated with special grease.
Carrying out a technical inspection on your own once a season will allow you to get rid of the need to repair the gearbox or replace it, with the purchase of an expensive new unit.
The starter is necessary to bring the trimmer into working condition, its diagnostics consists in checking the tension of the starter cord connected to the teeth of the starter coil, which are often destroyed during an abrupt start.
An inoperative starter in a petrol cutter cannot be repaired; it must be replaced with a working unit as part of a mandatory technical inspection or a set of repair measures.
Cutting elements require special attention and care, which must always be cleaned of dirt and cut grass after use. Regular inspection and thorough preparation of the device for operation will help to avoid costly and time-consuming repairs, and always be confident in the performance of the petrol brush.
Petrolcutters, like all petrol powered tools for the garden, are not difficult to maintain. It is possible and necessary to repair, configure yourself. For example, adjusting the carburetor of a petrol cutter with your own hands is a matter of five minutes.
The carburetor from the petrol cutter is a unit in the power system. In it, like any carburetor, there is a process of mixing air and fuel (gasoline) for further supply to the engine cylinders.
In this process, the main thing is the correct proportion of fuel and air, for which the carburetor is regulated.
Mesh filter. There are often only two problems with this element:
In order to find out the cause of the breakdown, the fuel filter cap is unscrewed to remove the strainer. If dirt simply accumulates on it, then flushing in gasoline or blowing will help.
If there is visible damage to the mesh filter, it is imperative to install a new one. There may also be damage to the fuel supply pipe (during repair, they practice checking this element).
The carburetor starter in most cases does not function due to blockages. Use acetone or the same gasoline for flushing.
Blowing compressed air into clogged carburetor parts is an acceptable and convenient repair practice.
The throttle body, the places where the carburetor parts are bundled, the inlet or outlet pipe - all of these parts are susceptible to depressurization. You can check for sure in a primitive way - smear the problem area with soapy foam.
The basis of the carburetor of the petrol cutter is an aluminum body. It contains a diffuser (hole with inner contours). Air is blown through this hole. The flow rate of oxygen (air) depends on the cross-section (orifice) of the diffuser.
The diffuser is equipped with fuel channels. From them, fuel is drawn in by means of an air stream.
Outside the carburetor is installed:
fuel pump;
jet system;
a system for adjusting the mixture of fuel and air;
The throttle valve determines the amount of air to be supplied, and the engine power directly depends on this.
Fuel is sucked into the carburetor system by a pump (its membrane). Then it passes through the choke in the carburetor. The fluid then flows through the pump inlet and outlet valves. Filtered by the grid. It moves through the needle valve into the diaphragm chamber.
Phased operation of the device:
Air supply to a tube with an air baffle (damper). The baffle regulates the intensity of the air flow.
The fuel supply system is necessarily narrowed by a diffuser to increase the flow rate.
Gasoline through the float chamber and the nozzle tube with a constriction. A float chamber adjusts the temporary volume of gasoline. In the float chamber, the pressure level is neutral, and in the tube with a constriction it is already low. Due to the differential pressure, the fuel penetrates through the nozzle.
The acceleration of the air flow facilitates the transfer of fuel (gasoline) and its atomization. As a result, an air-fuel mixture of the required proportion or density is formed.
The air / fuel mixture enters the engine cylinder through the fuel pipe.
The level of air density in the system depends on the area of the open air damper. The wider the throttle is open, the greater the fuel consumption and power.
Simply put, adjusting the carburetor on a petrol cutter is the creation of an optimal fuel mixture due to the correct air supply.
Before adjusting, the filters must be thoroughly cleaned according to the maintenance instructions in the instructions.
Further adjustment of the carburetor of the petrol cutter with your own hands is carried out with the adjusting screws. There are three of them:
Right (L) - adjustment of the fuel mixture for low rpm.
You need to find the maximum idle speed. To do this, slowly unscrew the screw (L) left and right.
To adjust, turn the screw a quarter of a turn always counterclockwise.
Lower (T) - is responsible for adjusting the engine at idle speed.
clockwise - increase;
counterclockwise - decrease.
For the correct adjustment of the idle speed, it is characteristic:
stable operation of a cold engine;
not overestimated speed of a hot engine;
a large reserve of turns for the trimmer head;
stable operation of the engine when changing position (sharp lifting or lowering of the knife).
Left (H) - regulation of the mixture at high speeds. (The screw is adjusted last).
The left screw (H) determines the general adjustment of maximum speed, engine power, temperature and gasoline consumption.
Setting up the carburetor of the brushcutter with the last screw is done as follows:
Open the throttle to full, while at the same time give full throttle. Turn the screw clockwise until the revolutions drop (in this case, orientate by ear).
Turn the screw counterclockwise as slowly as possible until the engine runs unevenly.
Then turn back quite a bit, barely hearing a stable, even operation.
For a more visual use of skills, it is more convenient to consider the work of an experienced user:
Interestingly, from the point of view of the author of the video, the setting (its correctness) is determined by the color of the candle, and not only by the speed and stability of the engine.
Correct adjustment of the carburetor with your own hands in this case - combustion of the fuel mixture without residue, the color of the candle should be light brown.
