Carburetor for a motor-block: adjustment, repair, maintenance tips
Along with the engine, the carburetor is one of the most important elements of a motoblock, the main function of which is to enrich fuel with air and supply the ready mixture to the engine of the unit. From time to time the carburetor of an agricultural machine requires adjustment, which will help reduce the amount of fuel consumed and increase the power of the power tiller. Adjusting the carburetor is not difficult, but before the work, you should prepare and learn the sequence of steps in this procedure.
The carburetor is the part of the fuel system that mixes liquid fuel with air, atomizes the combustible mixture, and delivers it to the engine cylinders. The correct operation of this node determines whether the combustible mixture will be enriched with oxygen to the right degree and fed to the cylinders in a timely manner. The name comes from the French word carburation, which means mixing. In the automotive industry, carburetor engines are gradually being superseded by injection engines, but in machinery, including gardening, they are used very widely.
The basic parts of a carburetor are:
The venturi tube is an orifice through which air enters the engine. Its distinctive feature is its hourglass shape. In the narrowest part is the slide valve (in rotary models it is a cylinder, in plunger models it is a slider). Narrowing of the air inlet increases air velocity and creates a low pressure zone. The result is quicker, more efficient fuel delivery and improved low- and idle-rpm performance.
The high and low revs needles are spools with a pointed needle going through a “socket”. Adjusts the fuel flow by the sharp tip. The further the needle is pushed into the seat, the smaller the gap and therefore the fuel flow.
The carburetor is an integral part of the fuel system
A carburetor works as follows:
- The piston moves upward, sucking the air out of the chamber.
- New air flows in through the venturi tube. The air is taken from the outside environment.
- At the same time, fuel from the tank is pumped into the chamber through the connection fitting.
- Fuel flows through the main needle into the Venturi tube.
- When the throttle lever is depressed, the low-rpm needle shifts and a gap is created, allowing fuel to enter the chamber. Air and fuel are then mixed into a fuel mixture, which in turn enters the engine cylinders, where it explodes.
- The fuel flow is then controlled by the position of the main needle.
Types of carburetors
- Float. Most modern carburetors belong to this type. It consists of a float chamber, a mixing chamber, and various metering systems and components: nozzles, jets, valves. The float chamber ensures a stable fuel supply. Nowadays this type of devices provide the most stable parameters of fuel mixture and are notable for high reliability.
- Diaphragm-needle. Such a carburetor consists of several chambers separated by membranes. The chambers are connected by a rigid rod. Fuel valve operation is regulated by a needle at the end of the stem. Unquestionable advantages of this carburetor type are simplicity of its device and its ability not to depend on its position in space (it can be turned and even turned upside down). These carburetors are installed on chainsaws, lawnmowers, etc. At the same time, they are difficult to adjust, sensitive to acceleration, slow to switch between modes and sometimes sin unstable composition of the mixture.
The following types are also distinguished:
- Rotary. The design is based on a horizontal cylinder with a cross hole. The cylinder rotates inside the chamber, allowing air to enter through the hole. At the same time the cylinder moves inside the carburettor. Low speeds are adjusted by changing the orifice size. These carburetors are simple in construction, but have comparatively little power and are unresponsive to operate. Ideal in applications that do not require hard acceleration and sensitive throttle at low speeds.
- Plunger (slider). Has a solid cylinder (no hole). Air enters when the cylinder is shifted. At low speeds, it is completely in the carburetor and blocks most of the air flow, resulting in lower rpm. When the accelerator pedal is depressed, the cylinder extends, letting more air and combustible mixture into the engine. Carburetors of this type provide more engine power, but makes it difficult to steer, especially on roads with low quality traction.
The design of the carburetor of agricultural machinery Neva is quite simple. Its study will not make much difficulty, but it will allow later without difficulty to make not only adjustment, but also repair. if there is such a need. This part includes the following components:
- The float associated with the locking needle valve;
- float chamber;
- chamber in which the fuel is saturated with air;
- diffuser and fuel atomization system;
- throttle plate;
- air and fuel valves.
The purpose of the float, connected with the needle-type valve, is to act as a sort of regulator, determining the volume of gasoline in the float chamber. When the amount of fuel drops, the float moves down and opens the valve, which “takes in” a new volume of fuel and replenishes it to the required quantity. The float moves up as the chamber fills up and closes the valve when needed, preventing excess fuel from entering the chamber.
In this video you will learn how to disassemble the carburetor:
The function of the atomizer, located between the float chamber and mixing chamber, is to distribute the fuel into the mixing chamber, where it is saturated with air. Air enters this container through the inlet. Here it is worth emphasizing that the gasoline level in the float chamber should always be a few millimeters below the outlet channel
It is important, because when the machine engine is off, fuel must not spurt out of the float chamber, not only when it is on a level surface, but also when the single axle tractor stands on a slope
Carburetor Care, Replacement, and Repair
Sometimes to bring a carburetor for a power tiller to a stable, working condition, adjustment is not enough, repair or replacement is necessary.
It is possible that the carburettor choke does not close completely. To remedy this problem, the drive should be monitored. If you find jams, correct them. over, considering that the carburettor provides the fuel and therefore drives the single axle tractor itself, you should closely monitor the condition of this part and take proper care of it.
To avoid serious damage to the carburettor, it is necessary to constantly monitor its operation. In addition to adjusting the idle speed, you should regularly clean the carburetor and replace worn parts. Since the carburetor interacts with the fuel mixture and air, the cause of its pollution can be in the first or second source.
To keep the contamination level significantly lower, filters can be used, which should be cleaned and replaced as necessary. In addition, the quality of the fuel has a significant impact. Poor-quality fuel fluid can damage parts and lead to premature replacement. If necessary, you can buy a carburetor for your power tiller at the car market or in a store. Its replacement, adjustment and cleaning are also performed by specialists.
How to adjust the carburetor of a power tiller with your hands
The adjustment of the carburetor of the motor-block carburetor should be carried out periodically in order to ensure proper operation of the mechanism. A carburetor may be a possible reason for a difference in the work of the engine of the motorblock. The unit is disassembled, cleaned and adjusted (adjusted). Regardless of the carburetor brand or what machine it is installed on, the principle of regulation is the same for all. Only the number of revolutions can make a difference.
The structure of the carburetor of a power tiller. learn the mechanism from within
The carburetor for your MotoBlock has a fairly simple design. Nevertheless, you should study it, because in future it will help to perform timely adjustment and self-repair of the unit.
The device available in the engine block carburetor consists of the following elements:
- a float connected to a needle-type shut-off valve;
- the float chamber;
- the air mixing chamber with the poured fuel;
- the diffuser and the fuel atomization mechanism;
- of the throttle valve;
- air and fuel valves with nozzles installed.
a float connected to the needle valve plays the role of a peculiar fuel quantity regulator in the float chamber. As soon as the fuel level drops, the carburetor float lowers, causing the needle valve to open. This helps to get the missing amount of fuel inside the float chamber. After the chamber is filled with gasoline, the float rises, closing at the same time the needle valve.
between the float chamber and the mixing chamber is the atomizer, which distributes the gasoline into the mixing chamber. There the fuel mixes with the air, which, in turn, enters the carburetor through the inlet. Fuel available inside the float chamber is always a few millimeters below the position of the outlet. To prevent fuel from splashing out of the float chamber when the engine of the power tiller is off. Especially necessary if the single axle tractor is located on a slope.
Components of the power tiller and what they do
The classic power tiller includes the following systems and elements. Fuel system. It, in turn, consists of a carburetor; a tank with a fuel tap; a hose through which fuel flows; an air filter. Starter. Performs the function of cranking the main shaft. It comes in two varieties: electric. Professional models of power tillers are equipped with it; manual. On power tillers used for domestic purposes, the function of cranking the main shaft is performed by the starter cord. Gas distribution system. Supplies fuel mixture to the engine cylinders and ensures that the formed gaseous waste is discharged. Ignition system. Is responsible for the spark formation.
Setting the carburetor: step by step instructions
Carry out the adjustment of the carburetor of a motoblock Cascade, which is the most important element, namely KMB 5, is not as difficult as it seems at first glance. The main task when working independently. to make adjustments in compliance with all the requirements and instructions. And it is necessary to act in a certain order.
First we start the engine and warm it up for a few minutes. After screwing in the throttle screws to the end, and unscrew them a turn and a half back. After that the throttle lever is set at the lowest rpm of the engine and the minimum traction speed of the walking tractor is set. After making this adjustment, the engine is turned off. To make sure the adjustment is correct, you need to start it, and if it runs almost without noise and interruptions, the work was done correctly.
If a single-axle tractor won’t start, shuts down, or rattles, there’s no need to take it to a service station. You can repair it with your own hands. To help the novice mechanic. videos that show in detail how to adjust the carburetor on the tiller. No special tools are needed for this, all work can be carried out in the field.
Before adjusting, it is advisable to study the manufacturer’s manual, which indicates the parameters of the optimal setting for this model.
- Warm the engine up for at least 5 minutes. Carry out adjustment with the engine warmed up and running.
- Screw the needles (screws) of minimum and maximum revolutions up to the stop.
- Loosen the screws by 1.5 turns
- To set the gear lever to its minimum value.
- By loosening and tightening the throttle valve screw, you should set the minimum RPM, at which the engine operates steadily, without interruptions.
- Set the maximum idle speed by adjusting the throttle trigger.
- Turn off and on the engine, checking to see if the adjustment is correct. If the engine becomes unstable again, repeat the steps.
Incorrect adjustment of the carburetor on the power tiller is the cause of the vast majority of malfunctions. By learning to adjust the device yourself, you can fix these problems on the spot, without condemning the equipment to downtime, and the economy to losses. But if you’re not confident in your abilities or if you can’t fix the device, it’s certainly worth turning to the experts.