Diy walbro carburetor repair

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Using the screws H and L, the ratio of the fuel-lubricant mixture and air is adjusted by opening the throttle valve. When the screws are tightened (clockwise), the mixture becomes leaner - low revolutions, when the screws are unscrewed (counterclockwise), the mixture is enriched, the revolutions increase

So, let's take a closer look at the partner chainsaw carburetor adjustment. It is worth noting that this example applies to the adjustment of the carburetor of the Ural chainsaw, and to the adjustment of the carburetor of the chainsaw calm.

Chainsaw carburetor adjustment.

The carburetor has three adjusting screws:
L - low speed jet screw
H - high speed jet screw
T - idle speed adjustment screw

Using the screws H and L, the ratio of the fuel-lubricant mixture and air is adjusted by opening the throttle valve. When the screws are tightened (clockwise), the mixture becomes leaner - low revolutions, when the screws are unscrewed (counterclockwise), the mixture is enriched, the revolutions increase.

Screw T adjusts idle speed. Turning clockwise increases the number of revolutions, counterclockwise decreases.

The basic carburetor setting is made at the factory during the saw test. The carburetor is adjusted for a richer than optimum mixture. This adjustment should be maintained during the first hours of saw operation. Then the carburetor is fine-tuned.

When turning the chain at idle speed, turn the screw T counterclockwise until the chain stops.

Fine adjustment of the carburetor can only be carried out in a warm state by specialists with special equipment (revolution counter).

The L screw is adjusted first, then the H and finally the T screw.

First you need to find the highest idle speed by slowly turning screw L clockwise (or counterclockwise). After finding the position of the highest revolutions, turn the screw L 1/4 turn counterclockwise. If the chain rotates at idle speed, turn screw T clockwise until the chain stops.

Adjusting screw H affects power and rpm. Lean carburetor adjustment will result in excessive revs and saw failure.

After warming up the engine at full speed for 10 seconds, turn the screw H by 1/4 turn counterclockwise. Let the engine run for about 10 seconds. Check the maximum speed with a tachometer. Repeat the operation if the maximum speed does not correspond to the passport one. The engine should sound like a four-stroke. Squeals when the chain is too lean. When the carburetor is adjusted to a too rich mixture, the muffler begins to smoke.

For optimal adjustment, you must contact a specialist with access to the tachometer.

Fine adjustment of the idle speed with the T screw is carried out after adjusting the L and H screws.

if it is necessary to adjust the idle speed, then with the engine running, the screw T must be turned clockwise until the saw chain starts to rotate. Then you need to turn the screw back counterclockwise until the chain stops rotating. The idle speed is set correctly if the engine runs evenly in all positions with sufficient reserve of revolutions when the chain starts to rotate.

The carburetor is properly adjusted if the engine accelerates immediately and noises like a full throttle four stroke.Adjusting the screw L to a too lean mixture will result in difficult starting and poor acceleration of the engine.

The carburetor has three adjusting screws:

L - low speed jet screw

H - high speed jet screw

T - idle speed adjustment screw

Using the screws H and L, the ratio of the fuel-lubricant mixture and air is adjusted by opening the throttle valve. When the screws are tightened (clockwise), the mixture becomes leaner - low speed, when the screws are unscrewed (counterclockwise), the mixture is enriched, the speed increases. The T screw regulates the idle speed. Turning clockwise increases the number of revolutions, counterclockwise decreases. The basic setting of the carburetor is carried out at the factory during the test of the saw. The carburetor is adjusted for a richer than optimum mixture. This adjustment should be maintained during the first hours of saw operation. Then the carburetor is fine-tuned.

Starting this article, I do not pretend to be the "last resort", and therefore any criticism, pointing out errors in the semantic content of the article and even in grammar are accepted in any form and in any volume. I would be glad to hear feedback and suggestions.
The article does not consider any specific carburetor model, since it is simply impossible to cover the entire range of carburetors manufactured by Walbro in the article. But given the increasing prevalence of engines of large cubes in modeling (which are also equipped with Walbro carburetors), I would like to explain the principle of operation and the physical processes occurring in carburetors with a built-in fuel pump. Understanding and correct representation of the processes taking place in the carburetor will allow the user to operate correctly and quickly eliminate the deviations from normal operation that have arisen.

General Provisions
The tasks of the carburetor include mixing fuel and air in an optimal ratio for any operating conditions of the engine, and as a result of fuel atomization, preparing the mixture for evaporation.
Fuel is atomized in the carburetor and only a small portion of it evaporates. (for this, manufacturers
some effort is made - for example, a heat-insulating gasket between the carburetor and the crankcase). The heat necessary for the evaporation of fuel is taken from the parts of the power plant itself, with which the fuel mixture comes into contact during its flow in the intake tract. And further complete evaporation of the fuel mixture occurs already in the engine cylinder.

The removal of heat from engine parts necessary to evaporate the fuel mixture, causing these parts to cool down is called internal cooling.

Theoretically, with a fuel mixture of 14.8 kg of air and 1.0 kg of gasoline, the air number lambda = 1
At this ratio, the fuel mixture burns out completely.
This attitude is called ideal.
The fuel mixture is combustible with lambda values ​​between 0.7 and 1.25.

The actual properties of the fuel mixture differ from the theoretical ones, depending on external conditions (temperature, air humidity, atmospheric pressure) and on the engine operating modes themselves (start, idle, partial load, full load).
If the actual composition of the mixture differs from the ideal, then the mixture is either lean or rich.

Poor mixture contains more air
With a lean mixture, due to a lack of fuel in the mixture, the engine does not develop full power, in addition, the engine has an increased temperature due to the worst internal cooling.
Due to the reduced volume of the oil-containing new portion of the fuel mixture, the lubrication conditions deteriorate, which leads to an increased risk of scuffing the piston-cylinder pair.

A rich mixture contains less air.
With a rich mixture, incomplete combustion of the fuel mixture occurs. The unburned mixture also shows itself in the form of smoke from the muffler.

Design and function
Consider the general design of a carburetor with a built-in fuel pump.
Carburetor

Chainsaw carburetor adjustment

The carburetor has three regulating screws:

L - low speed jet gwent

H - gwent of a jet of high wraps

T - idle speed regulation

For the help of the H and L gvints, the control of the fire-and-mastic sums is regulated and, as it happens, the opening of the throttle flap starts. When twisted gwints (for a year old arrow), it’s crazy to grow up - low wraps, when you wind up guints (against a year old arrow), it’s back to backward, turn to grow.

Gwent T adjusts idle wrap. When turned over a year old arrow, the number of wraps increases, and against a year old arrow, it changes.

The main setting of the carburetor is carried out at the virobnik plant when the file is vyprobuvanny. The carburetor adjusts to the bagatsu below the optimum sum. The same regulation is to blame for the first years of the robotic file. Then the carburetor is more precisely regulated.

Adjusting the carburetor of the chainsaw When wrapping the lancet on blank wraps, it is necessary to turn the gwent T of the antigodinnikovaya arrow until the lanceyug is quietly turned off.

Accurately regulating the carburetor can be carried out only in the rosette station with the help of special possessions (turnover switch).

Some gwent L can be adjusted, sometimes H and in kintsi gwent T.

A lot of it is necessary to drive the most idle speed, by and large turn the screw L for the old arrow (or against). To make sure that the largest wraps are placed, it is necessary to turn the screw L by 1/4 of the wrapper against the old arrow. Yaksho lantsyug at all turn around at idle speed, turn gwent T, having forgiven the year's arrows, leave the lantsyug not to zupinitsya.

The regulation of the gwent N is injected into the tightness and the frequency of wraps. Adjust the carburetor to make the sum up to overspeed, and drank it out of the way.

While running the motor on the main run in the plinth for 10 seconds, turn the screw H by 1/4 the wrap of the anti-clockwise arrow. Dati dvigunu popratsyuvati close to 10 seconds. Change the maximum wrap with a tachometer. Repeat the operation in case of inconsistency of the maximum wraps in the passport. Dvigun is guilty of pratsyuvati by the sound of yak chotiritaktny. When it’s busy, it’s a saw to squeal. When the carburetor is adjusted on the back of the bagatu, the muffler will fix the dimity.

For optimal regulation, it is necessary to turn up to the fachivtsya, you can access the tachometer.

More precisely regulation of idle turnover with the help of the gwent.

If there is a need to adjust the number of idle wraps, then when the engine is running, it’s necessary to turn over the old arrow, while the pilal lance doesn’t turn around. Then it is necessary to turn the gwent back against the old arrow until it stops turning. The number of idle wraps is set correctly, as long as it moves smoothly in all conditions with a sufficient supply of wraps, if the lance starts to wrap around.

The carburetor adjusts correctly, so that the engine does not run smoothly and is noisy because of the new gas. Adjust the gwent L on the back to the bottom of the sumish until the difficult start and the filthy sprint of the dvigun.

Wee read the article on the topic - Chainsaw carburetor regulation
chainsaw trike

Many owners of such garden equipment are wondering how to regulate the number of revolutions in their unit. We will give the answer to this question in this article on adjusting the chainsaw carburetor.
How to set up a chainsaw carburetor

In general, almost all carburetors, be it the Stihl chainsaw carburetor or the Ural chainsaw carburetor, have three adjusting screws. The screw, designated T, adjusts the idle speed.The L screw controls low rpm and the H screw controls the high rpm, these elements also regulate the fuel / lubricant mixture and air ratio. While tightening the screws clockwise, the carburetor of the chainsaw calms down to low speed, as the fuel mixture becomes leaner. When unscrewing in the opposite direction, the fuel-lubricant mixture is enriched, therefore, the speed increases. The T screw, which is, for example, the carburetor of a husqvarna chainsaw, regulates the idle speed. Turning it clockwise increases the idle speed, in the opposite direction it decreases.

The basic setting that a chainsaw carburetor undergoes occurs at the factory during the testing of the tool. A more accurate carburetor adjustment is made after the first few hours of operation.
Chainsaw fine tuning

The exact adjustment to which the carburetor of the Ural chainsaw is subjected should be carried out only in a heated state, preferably by specialists with the necessary equipment. The order of adjusting the screws is as follows: first screw L, then H and finally idle screw T.

First, the highest idle speed is determined. To do this, screw L is slowly turned, and after the position of the highest revolutions has been found, the screw is turned ¼ of a turn against the clock.

The H screw affects the power and speed at which the carburetor of the chainsaw is calm. It is necessary to warm up the engine at full speed for 10 seconds, turn the screw ¼ of a turn against the clock. Let the engine run, and then check the maximum rpm with a tachometer.

Fine adjustment of the T screw is carried out with the engine running, the screw is turned clockwise until the saw chain starts to rotate. Then screw T must be turned in the opposite direction until the chain stops.

To adjust the imported husqvarna chainsaw carburetor, it is best to contact a specialist who can correctly adjust all the necessary parameters using a tachometer.

What keys do we use?: Adjusting the chainsaw carburetor partner adjusting the chainsaw carburetor Ural adjusting the chainsaw carburetor calm

A chainsaw is needed in construction, and in gardening, and in landscaping - its presence greatly simplifies the implementation of a number of tasks for processing wood. The main unit of this tool is the engine, the operation of which largely depends on the state and settings of the carburetor. This is where the fuel mixture is prepared. This means that if the saw does not start, stalls or does not provide the required power, it is likely that the reason for this is improper operation of the carburetor. Fortunately, you can handle this yourself in many cases. Only for this you need to know and understand the device and principle of operation of this unit and, of course, the chainsaw itself.

The main purpose of the carburetor is to mix fuel with air in the required proportions. If the latter are violated, this is almost instantly reflected in the operation of the engine.

Stihl MS 181 C BE chainsaw carburetor

Chainsaw carburetors may vary in design. However, their basic elements and the principle of operation remain approximately the same.

Carburetor device:

This is a wind tunnel, across which the air damper is located - with its help the intensity of the air supply is regulated.

This part is located where the base tube is narrowed - here the air flow rate increases, i.e. air is always supplied to the carburetor under some pressure.

In this area, the fuel comes into contact with the air stream. Fuel enters the atomizer from the float chamber through the nozzle (metering device).

1. Float chamber

This is a container that allows you to keep the fuel mixture in a stable state.

Structural diagram of a chainsaw carburetor

The chainsaw carburetor works according to the following principle:

• when the engine is started, the main flap opens and a stream of air is supplied into the air channel at a certain speed;
• the air flow rate, as well as the level of the float in the chamber, are regulated by the position of the damper, namely, due to the difference in pressure in the float chamber and the air channel;
• the fuel from the float chamber is sucked into the nozzle, and from there into the diffuser;
• passing through the diffuser, the air captures the fuel entering there;
• the resulting mixture is fed into the cylinder chambers through the inlet channels.

The principle of operation of the chainsaw carburetor

The pressure in the float chamber is approximately equal to atmospheric, but in the air channels of the carburetor, when the engine of the chainsaw is started, a vacuum occurs. Opening the damper increases the air flow rate. As a result, more fuel flows into the carburetor, and the number of revolutions of the engine shaft increases.

In the first hours of operation, the 2-stroke engine of the chainsaw requires running-in, on which the quality of its further work depends. During the running-in process, the primary adjustment of the carburetor is performed - the optimal parameters for the preparation and supply of the fuel mixture are set.

Chainsaw initial break-in: working with thin material

Most modern chainsaws are sold adjusted. Nevertheless, the quality of the factory settings does not interfere with checking - in the end, you will have to work with the instrument.

The first time you start the chainsaw, it must be gentle. Therefore, for several hours after the start, it is recommended not to overload the engine and only cut small branches and trunks up to 10 cm thick.

To insure against malfunctions in the carburetor of the chainsaw, simple rules will help:

Always mix gasoline and oil in accordance with the manufacturer's numbers.

The proportions of the fuel mixture for the chainsaw engine

Do not prepare the fuel mixture in advance - the properties of gasoline and oil when mixed will lose over time. An exception is fuel for an intensively used tool, however, here, one should not exceed the approximately weekly rate.

Use the oil specified for your chainsaw engine. A fuel mixture with a non-standard composition will disable it seriously and for a long time.

When preparing the fuel mixture, take into account the influence of climatic conditions on its components.

The chainsaw must start correctly, provide a stable sprocket speed and smooth power increase / decrease. When the engine is running, there should be no extraneous knocks, pops and noises.

Professional hand-held chainsaw at work

The main thing during the initial running-in of the tool is to ensure that the fuel consumption corresponds to the power used, i.e. in practice, the saw should not go out, "sneeze", smoke and work in jerks.

Typical carburetor malfunctions are easy to recognize. They are expressed in the fact that the engine of the chainsaw starts up and immediately stalls or does not show signs of life at all. Well, or it consumes fuel with might and main, producing clouds of black smoke and aggressive vibrations instead of the required power.

Chainsaw carburetor operation diagram

Carburetor settings can be affected by:

lack of fixing the adjusting screws;

Chainsaw adjusting screws

New CPG chainsaw Husqvarna 365

blockage of the fuel-air channels;

damage to air filters;

Chainsaw air filter with nylon insert

If any problems are found, they should be rectified immediately. But how do you know if the carburetor is the problem? To do this, watch how your tool works.

Typical signs that carburetor settings are out of order include:

1. Unstable motor operation

As a rule, the reason for this is the use of an incorrect (lean) fuel mixture.

1. Excessive consumption of fuel

It is expressed in an increased emission of waste exhaust, which turns black. This means that the fuel is not completely consumed, i.e.the mixture is oversaturated.

Carburetor set correctly - saw starts the first time

May be associated with damage to the fastening of the adjusting screws or the protective cap.

1. Increased fuel consumption accompanied by vibrations and pops

It speaks of critical wear of the piston group, therefore, adjusting the carburetor will postpone the overhaul only for a while.

1. "Sneezing" and engine jerking

This picture is observed when the carburetor channels are clogged or its filters are malfunctioning. In this case, adjustments should only be made after thorough flushing of the assembly.

Chainsaw fuel filter

Despite the fact that the carburetor is the most difficult part of the engine, you should not be upset if it detects malfunctions in its operation. Instead, you need to arm yourself with some tool, a knot design, and some healthy logic.

Chainsaw carburetor being repaired

First of all, you need to prepare a place for disassembly. This can be a workbench or a regular table. In addition, you need a rectangular piece of cloth or cardboard - on it you will neatly fold the carburetor parts. And, finally, a tool: for disassembly, you will need a set of open-end wrenches and screwdrivers, a special cleaning compound and an ultrasonic cavitation bath.

Chainsaw carburetor repair tool

First, you have to dismantle the chainsaw carburetor. This is done in this order:

To get to the carburetor, you need to remove the top cover of the chainsaw, which is fixed with three bolts.

Removing the carburetor cover

After removing the cover, do not forget to remove the gasket, which is an integral part of the air filter, and the body of the latter, for which you need to unscrew the corresponding nuts and / or remove it from the clips.

On the right side of the carburetor there is a fuel hose, it must be removed together with the air damper drive rod, not forgetting to pull it off the fitting on the left.

Removing the fuel hose and drive rod

After removing the hose and rod, remove the throttle cable tip from the fixing socket and finally dismantle the gasoline hose.

Removing the throttle cable

The carburetor can then be removed from the mountings for later disassembly.

After removing the gasoline hose, the carburetor is ready for disassembly.

Disassembly of the carburetor must be carried out in the manner prescribed by the design and functional solutions of its elements. Chainsaw carburetor parts do not differ in size, so they need to be folded carefully and in order, trying not to lose anything.

After disassembly, it is necessary to carry out troubleshooting and replace damaged or worn parts. Next, the entire set should be rinsed with a special product, dried and wiped with a dry, lint-free cloth. The jets and tubes of the assembly must be blown out with compressed air, or, in order to more thoroughly remove the formations on their inner surfaces, they must be treated with ultrasound before that.

Reassembly of the carburetor is carried out only after complete cleaning, drying and blowing with compressed air. At the same time, do not forget that some gaskets and seals, even if they are not damaged, must be replaced.

You can start adjusting the carburetor provided it is correctly troubleshooting, high-quality assembly and flawless re-installation on the engine.

Carburetor setting principles:

• screws H and L adjust the ratio of air and combustible mixture, i.e. throttle position. Tightening the screws clockwise leads to a depletion of the mixture and the transition of the engine to low revs. When unscrewing (counterclockwise), the mixture is enriched, and the engine speed increases;
• screw T is responsible for adjusting the idle speed: turning it clockwise gives an increase in their number, against - a decrease;
• screws are adjusted in L-H-T order.

Chainsaw Carburetor Calibration

The general adjustment algorithm looks like this:

1. Initially, the highest idle speed is found by turning the screw L and then returning it by ¼ turn counterclockwise. If the chain rotates at idle speed, turn the screw T in the same direction until it comes to a complete stop.
2. With the engine warm, running at full speed, turn the screw H by ¼ turn to the left, then let the engine run for 10 s, check the maximum speed using a tachometer. It must correspond to the number indicated in the instrument's passport.
3. After the calibration with screws L and H, the idle speed is adjusted with screw T. If done correctly, the engine will run evenly in all positions.

Memo for calibrating the carburetor on the body of the chainsaw

Upon completion of the adjustment, it remains to reinstall the cover of the chainsaw with an insulating gasket, after which you can start the main work. If the settings are correct, the chainsaw engine will get the optimal fuel mixture. This will ensure its normal efficiency, as well as the overall comfort and safety of working with the tool.

The engine picks up speed poorly, runs intermittently, power decreases... These problems are often caused by a clogged air filter.It will be necessary to remove the cover that covers the filter and clean it, which consists in washing with detergent.

In general, timely adjustment, as well as timely repair of the chainsaw carburetor, can significantly extend the life of the entire piston system of the engine. Therefore, the tuning of this component of the fuel system must be treated with great care.