Petrol Trimmer Carburetor Adjustment

Adjustment and repair of the carburetor lawn mowers Instructions for adjusting the carburetor lawn mowers.

Principle of operation

The carburetor is a power system module in which liquid fuel and air are mixed before being fed into the engine cylinders. Mixing and feeding are adjusted accordingly depending on the tool and its mode of operation.

The carburetor device for lawn mowers is the same for almost all cases. It belongs to the category of float devices. The latter provide stable parameters of ready-made mixtures.

petrol trimmer carburetor adjustment

The principle of the module is as follows.

  • Air enters the body of the air damper tube. The latter increases or decreases the air flow depending on its position.
  • In the area where the gasoline feed hole is formed, the tube has a narrowing diffuser. Here the flow rate increases.
  • Fuel from the float chamber is fed through the nozzle into the tube. The float level determines the amount of fuel supplied. Since the pressure in the chamber is normal, and in the tube it is low due to the greater rarefaction of the air, gasoline is sucked in through the nozzle.
  • The accelerated air flow picks up the fuel and sprays it, forming an air-fuel mixture of the desired density.
  • The mixture is sucked into the cylinder through the pipeline.

The more open the air damper in the tube, the higher the density of the air flow, which means more fuel enters the cylinder. Adjusting the carburetor of lawn mowers is reduced to setting such a ratio of flaps, at which the density of the fuel mixture becomes optimal.

Adjusting and repairing the carburetor lawn mowers

The trimmer does not belong to complex household appliances, therefore most of its breakdowns are mechanical in nature and are quite successfully eliminated with their own hands. Even if the engine fails for serious reasons, damage to the piston ring, for example, repairs are reduced to replacing a part.

But even with a relatively simple design, such a part of the device as the carburetor needs to be adjusted.

Signs of imbalance

Debugging the carburetor must be done during the manufacture of the device. As a rule, the owners will learn about the need to adjust the fuel supply with their own hands only after serious enough breakdowns, in the process of correcting which, the module was removed and, for example, cleaned.

Signs of a configuration failure are the following:

  • Starts, but the engine immediately stalls because the engine can only work when a certain amount of gasoline is supplied, with too lean fuel, that is, blocking the supply channel, the engine will stop;
  • Too high fuel consumption, a lot of exhaust gases are the result of incomplete combustion of the mixture. In this case, on the contrary, there is too much fuel and the mixture is too dense.
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Carburetor Adjustment Lawn Mowers Highlights

Despite their high productivity, mobility and unpretentiousness in work, modern lawn mowers can hardly be attributed to complex devices. Over time, any mechanism is subject to wear and tear, and therefore parts and assemblies require special attention from the owner. One of these trimmer elements is the carburetor, designed to form a fuel mixture and feed it into the combustion chamber. Increased fuel consumption with proper observance of the proportions of gasoline and oil or a drop in engine power indicate the need to adjust the carburetor of the gasoline trimmer.

Adjusting the maximum speed screw for lawn mowers

After restoring the fuel supply at minimum speed and adjusting the idle speed, it is necessary to check the stability of the mechanism at an increased speed.

Tuning at maximum speed

The motor is adjusted at high speeds in order to protect against overheating and to reduce hand fatigue when pressing the accelerator button. If the internal combustion engine is unstable at maximum speed, screw H must be tightened slowly until smooth and precise operation is ensured.

During operation of the lawn mower it may be necessary to readjust the fuel screw (L) for optimal speed gain.

Adjusting the fuel supply at minimum speed

Before you start tuning the carburetor of the petrol trimmer, you need to warm up the engine to operating temperature.

Fuel adjusting screws

To do this, we start the internal combustion engine and, at idle, let it run for 10-15 minutes. In the first step, with the trimmer running, slowly tighten screw L until intermittent operation starts or until it stalls. Next, unscrew the screw ¼ of a turn and check the maximum speed set. If the lawn mower reaches high revs quickly and easily, this will be the most economical mode. In most of the models on the market, the fuel screw L is turned clockwise, however, there are trimmers where the decrease and increase in the mixture flow occurs in the opposite order.

Fuel ratio

I read somewhere that if different mixing ratios are indicated in the lawn mower’s manual and on the oil canister, the proportion indicated in the manual should be used.

For a long time, it did so from the engine to the gas tank, excess oil flowed down and carbon deposits constantly formed on the candle, since the manual indicated the proportion for the run-in engine 1:25, and on the canister 1:50. After switching to a 1:50 ratio, the appearance of oil drips stopped. The plug continued to burn, but with less intensity (the carburetor was not yet adjusted).

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Until now, some users of gasoline tools determine the proportion of the fuel mixture by eye. If the amount of oil is lowered during the preparation of the mixture, after a while an extraneous sound may appear immediately after starting the engine, gradually disappearing during warming up, and the engine stops with a sharp jerk. Continued use of the trimmer in this mode will result in its failure.

Carburetor adjustment

Flush the air filter before adjusting the carburetor. It is recommended to rinse it after every 10 hours of operation. After that, you can start adjusting. The photo shows the PRORAB-8406 petrol trimmer carburetor as an example. The numbers indicate the adjusting screws that we will use.

PRORAB-8406 petrol trimmer carburetor adjusting screws

Purpose of adjusting screws:

  1. Fuel mixture adjustment screw.
  2. Idling adjustment screw.
  3. Maximum speed limiting screw.

Start a lawn mower and wait for it to warm up.

Adjusting the carburetor lawn mowers, trimmer

Increased fuel consumption and the rapid formation of carbon deposits on the spark plug when using a properly prepared fuel mixture indicate the need to adjust the carburetor. Here’s how to tune trims with carburetors that have one fuel trim screw.

When is adjustment necessary at all?

Specifically, adjusting the carburetor of a chainsaw is required in rare cases, more often there are problems associated with the flow of fuel or wear of parts. But sometimes the symptoms indicate that it is necessary to precisely adjust the mechanism. Here are some signs:

  • After the engine starts, it immediately stalls. Alternatively, it will not start at all. The reason lies in the excess air and fuel shortage.
  • Increase in fuel consumption, and as a result, a large amount of exhaust gases. This is due to the reverse process of oversaturation of the mixture with fuel.

The reasons for the adjustment failure can be mechanical:

  • Strong vibration damages the protective cap, causing all three bolts to lose their position.
  • Due to wear on the piston part of the engine. In this case, adjusting the carburetor of the chainsaw will only help out for a while, it is better to replace the worn part.
  • Due to clogging caused by low-quality fuel, scale or damage to the filter. The carburetor requires complete disassembly, flushing and adjustment.

If the chainsaw suddenly stops working, you need to disassemble it to find out the reasons

Chainsaw carburetor adjustment: we analyze all the technical nuances of the work

Summer cottage construction and repairs are not complete without the use of a chainsaw, as well as garden maintenance. Due to a malfunction of the tool, all work can get up, so it is so important to be able to disassemble it yourself, find problems and fix them. With enough experience and skill, it is even possible to adjust the carburetor of a chainsaw, the procedure is complicated, or rather, jewelry. How to carry out the adjustment procedures, we suggest you disassemble today.

Step by step instructions for disassembly

The carburetor device of models of different brands is almost the same, so take the Partner chainsaw as an example. We carefully remove each element and put it in order to make it easier to assemble later.

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Chainsaw carburetors from different manufacturers, if they differ, it does not matter

The top cover is removed by unscrewing three screws. It is followed by foam rubber, an integral part of the air filter.

The arrows indicate the bolts that must be unscrewed to remove the cover

Then we remove the fuel hose, followed by the drive rod.

The upper arrow points to the fuel hose, the lower arrow to the drive rod

Next, remove the tip of the cable.

The arrow shows the end of the cable to be removed.

On the left from the fitting, we pull together the gasoline hose.

We also carefully remove the gasoline hose indicated by the arrow

We finally disconnect the carburetor, it is ready for adjustment. Its mechanism is rather complicated, therefore, if further disassembly of the carburetor is required, the elements should be removed very carefully, they are small, therefore they can be lost.

The carburetor consists of many small parts, which should be laid out in order during disassembly.

The main problems and malfunctions of the carburetor.

Mesh filter. There are often only two problems with this element:

  1. Blockage.
  2. Breaking.

In order to find out the cause of the breakdown, the fuel filter cap is unscrewed to remove the strainer. If dirt just 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 carburetor parts is an acceptable and convenient repair practice.

Do-it-yourself lawn mowers carburetor adjustment

Lawn mowers, like all gas powered garden tools, are not difficult to maintain. It is possible and necessary to repair, configure yourself. For example, adjusting the carburetor of a lawn mower with your own hands is a matter of five minutes.

A lawn mower carburetor 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.

Lawn mowers carburetor device

The base of the carburetor is an aluminum body. It contains a diffuser (hole with internal 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. Fuel is drawn in from them using an air stream.

Outside the carburetor is installed:

  • Fuel pump;
  • Jet system;
  • Fuel-air mixture control system;