How to adjust the carburetor on a Goodluck chain saw

adjust, carburetor, chain

Setting the carburetor of a chainsaw: adjustment of different models (features)

On its way from the fuel tank to the combustion chamber, the mixture bypasses a very important element of the. The carburetor that supplies the engine with a regular supply of fuel has a particular influence on the chainsaw’s performance. Even a small malfunction in the settings of the miniature mechanism of this device, causes pronounced deviations in the work of the entire tool, reducing efficiency and increasing fuel consumption. In this topic, you’ll learn how the adjustment screws affect the system and how to achieve their optimal position.

The more complete the understanding of the principle of operation of the device, the easier it is to operate, maintain or repair. The mechanism of the carburetor is quite multifaceted and interacts with several adjacent assemblies (crankcase, gas pedal and tank). It is actuated by tremors of air, wiggling the diaphragms, but more about that in due time. For now, let’s look at the device in general.

As should be the “heart” of a fuel system, the carburetor design is not simple, but is understandable with a smooth and consistent disassembly. Let’s start with a general list and go straight to the interaction of components. Depending on the model, the mechanism may contain about 20 parts, the location of which is clearly illustrated by the following diagram of a modern chainsaw carburetor (actual since the 90s).

adjust, carburetor, chain
  • Fuel connection. Connects to the hose from the gas tank.
  • impulse line nozzle. Connects to the engine crankcase, which displaces and sucks in air that acts on the diaphragm.
  • Fuel pump diaphragm. Performs the function of pumping the fuel into the chamber and its further supply into the fuel channel.
  • Inlet valve. Controls movement of mixture, allowing it to enter the diaphragm chamber and limiting movement back.
  • Exhaust valve. Functionally identical to the previous item, but controls overflow from the diaphragm chamber to the fuel line.
  • Filter element. The final frontier for keeping fine particles out of the fuel. Made in the form of a fine mesh screen.
  • Fuel line. Supplies mixture to the bottom of the carburetor.
  • Needle. Blocks the fuel channel, keeping the mixture from flowing back to the top of the mechanism. Functionally similar to valves, but with a more complex design.
  • Control diaphragm. Acts on the needle through a spring-loaded lever mechanism, changing its position depending on the amount of fuel in the chamber.
  • High speed adjustment screw (H). Connected to a needle whose tip restricts flow to the stroke and idle nozzles.
  • Operating stroke restrictor. Provides metered flow of mixture to sprayer.
  • Idle speed adjustment screw (L). Identical in structure and function to the previous screw, but its needle limits the flow to the other two outlets.
  • Middle (left) and idle jets (right). Process ports that produce a regular injection of mixture into the mixing chamber with air.
  • Throttle valve. Auxiliary component required to start a cold engine. In operation, always in the open position.
  • Throttle valve. Adjusts the fuel mixture intake volume in the mixing chamber. In the closed position engages only 1 idle throttle, and when open, alternately activates the other 2.
  • Diffuser. The constricting part of the carburetor‘s main channel, where the fuel and air mix. The peculiar shape, provides an increase of speed of airflow.
  • Fuel cell. Fuel mixture accumulation place, where it is fed by the diaphragm pump, and from where it is distributed, passing through the nozzles into the mixing chamber.

The mixture starts its high-speed route through the fuel system of the instrument, from there it is sucked in through the filter and through a hose, through the nozzle, goes to the fuel pump chamber, passing the inlet valve. As the engine piston rises, the air in the sealed crankcase is compressed, pressing the diaphragm against the top cover, to which it connects through the impulse hose (this is how gasoline is pumped in). When the piston goes down, the pressure in the crankcase increases and bends the diaphragm in the opposite direction, directing the accumulated in the chamber mixture through the only accessible way, through the exhaust valve into the fuel line.

Prior to entering the fuel cell, fuel flows through the homologous channel through the cone shaped needle tip which is compressed to the passage port by a spring. The position of the needle is controlled by a control diaphragm that retracts into the carburetor when a vacuum is formed, pushing the tip back and allowing the mixture to enter the chamber. When filling (even partially), the vacuum weakens and the spring presses the needle again, closing the channel.

From the fuel chamber, the mixture is directed to the nozzles, passing through the technical openings, the width of which is regulated by the screws (L and H). At the outlet of the nozzles, the fuel is caught by the air current and atomized to small particles. With the throttle closed, fuel is drawn only from the last port (idle) closest to the engine. When the throttle trigger is pressed smoothly, the flap opens, gradually increasing the activity of the neighboring nozzle (middle stroke). In the maximum position, the outermost atomizer (high rpm) is engaged, increasing the amount of fuel and piston speed, speeding up the whole system.

Tuning tools

Like any maintenance procedure, chainsaw adjustments require certain tools that allow you to interact comfortably and efficiently with the mechanism. Fortunately, the basic arsenal for conducting such an event, consists of only one slotted screwdriver with a long rod. Important for 95% of carburetors, domestic, amateur and professional chainsaws.

The most precise adjustment is made with a special electronic device that reads the speed of the crankshaft. If you want to get optimal results, it is better to buy a budget tachometer and figure out how to measure the RPM of a chainsaw with a simple and effective method. For experienced users, who can distinguish defects by the sound, the device is not particularly useful, but beginners sawyers can seriously help.

Some manufacturers overly unique their products, equipping them with elements with a non-standard design. For example, adjusting the carburetor of a Husqvarna 135 or Jonsered CS2238 chain saw requires a screwdriver with an extremely unusual shaped bit that you can not get everywhere. This complicates the procedure of self-adjustment and forces to turn to special. service. If your saw’s carburetor has unusual screw heads, but you want to do the adjustment yourself, it is better to order the required tool in advance (you can find it on ali and in some online stores).

Tuning tools

Like any maintenance procedure, chain saw adjustments require certain tools that allow you to interact comfortably and efficiently with the mechanism. Fortunately, the basic arsenal for such an activity consists of just one long-stemmed slotted screwdriver. Applicable to 95% of carburetors, domestic, amateur and professional power saws.

Maximum fine tuning is done with a special electronic device that reads the speed of the crankshaft. If you want to get an optimal result, it is better to buy a budget tachometer and figure out how to measure the RPM of a chainsaw with a simple and effective method. The device is not particularly useful for experienced users who can distinguish defects by their sound, but for beginner sawyers it can be of great help.

Some manufacturers overly unique their products, equipping them with elements of non-standard design. For example, adjusting the carburetor of a Husqvarna 135 or Jonsered CS2238 chain saw will require a screwdriver with an extremely unusual shape bit, which you can not get everywhere. This complicates the procedure of self-adjustment and makes it necessary to apply to special service. service. If your saw has unusual screw heads on the carburetor, but you want to do the adjustment yourself, it is better to order the required tool in advance (you can find it on ali and in some online stores).

Adjusting the carburetor of a Chinese chainsaw

Once you’ve mastered the theory and have the proper tools ready, you can confidently move on to the process. The first instruction deals with domestic and amateur saws with standard carburetor types, which are more widely used than the more expensive brands. Here are described the nuances of adjusting the classic model at 45-52 cc (with and without primer). To fully convey how to adjust the carburetor on a Chinese chainsaw, each movement and task is explained.

For understanding, let’s briefly label each screw and its purpose. L (Low). is responsible for low and medium revolutions. H (Hight). adjusts RPM at maximum stroke when the throttle is fully open. T (TAS). Throttle Adjustment Screw). adjusts throttle gap when throttle is closed, affecting idle RPM when throttle is fully released. The rotation of the screws, is done through special holes located on the left side of the tool.

First of all, the saw has to be started and warmed up, about 1 minute with a short startup. If the engine refuses to start because of an out of tune carburettor, it should be reset to the factory settings by turning the screws all the way in (clockwise, without fanaticism) and unscrewing them to the desired position. The standard number of revolutions from the zero point for the carburetor at 45-52 cm³, without primer, is 2 full turns for the screw L, and 2.25 turns for screw H. With the primer, the low values are slightly different: L = 2.25, and H = 2.25 turn.

To clarify the position when turning, a mark can be made on the handle or rod of the screwdriver. You could draw it with a marker, glue a thin strip of duct tape on it or mark it with a file.

Adjustment of the carburetor is performed with the engine running and starts with the screw L. By turning the screwdriver counterclockwise (½ to 1 full revolution) the chain will rotate.), it is necessary to achieve maximum rpm at idle speed. The main thing is to be careful not to turn the screw all the way back.

Following the low revs, adjust the idle speed screw (T), which is responsible for the base position of the throttle. Tighten the screw until the chain starts to move, then unscrew it (about 1/2 way) until the chain stops. This way the optimum distribution at idle speed is achieved.

The final stage of adjustment involves the last screw (H), which is responsible for high revolutions when the throttle trigger is pulled completely. To see the change in performance, the throttle has to be fully open, so you have to hold the throttle for a moment to adjust. Just turn the screw slightly clockwise or counterclockwise to get an adequate engine sound. Without tachometer, this operation is done by ear, trying to achieve a moderate heartbeat (the saw should not roar).

When measuring with a tachometer (on a 45 engine), the following values should be achieved: 10,000 rpm for maximum stroke and about 3,000 for idle. For engines with other displacements, the plus and minus values are similar.

For a more complete and clear view of the process, check out the following video showing how to adjust the carburetor on a Chinese chainsaw. The video contains valuable Комментарии и мнения владельцев from an experienced rebuilder, and shows techniques for perfect tachometer tuning. Even if you adjust by ear, you can be guided by the sound of the engine from the video.

Adjusting a chainsaw carburetor

Most chainsaws have three adjustment screws on the carburetor. In order about each:

  • T.Idle speed screw. The idle speed screw controls the throttle valve position when the throttle trigger is fully released. If the choke is not open enough, the engine will stall when the handle is released because the choke will cut off the fuel mixture. In case when throttle is opened more than it should be, the chain will rotate, which is categorically forbidden by the safety regulations when working with a chainsaw.
  • L-Screw for low RPM. This screw controls the amount of fuel in the fuel mixture when the chain saw is idle. If the fuel quantity is too much, engine will choke under load, if there is not enough fuel, engine overheating, scuffing will follow.
  • H-High RPM adjustment screw. Adjusts the amount of fuel in the fuel mixture when the chain saw is running. If this adjustment is set for a larger amount of fuel, the engine won’t run in a rush and it will smoke and if it is set for less, you will get too high rpm and overheating.

Carburetor adjustment step by step

  • Check the condition of the air filter. Remove and either clean or replace. If the air filter is clogged with dirt and sawdust, chain saw operation will not be normal.
  • Check the condition of the silencer. The muffler should be clean and unclogged. Learn more about silencer cleaning TEXT.
  • Before you start adjusting the carburetor, it is worth to fill the fuel tank at least half.
  • If the chainsaw is able to start it should be run for a few minutes to warm up. If you adjust it “in the cold”, the mixture will be over-enriched after warming up.
  • Start with the idle speed adjustment. screw L. It is highly desirable to have a tachometer, then we focus on 2700 rpm. If not, we need to find the highest rpm at idle. The chain should not rotate. If it still revolves (of course the chain, not the ground) stop it by turning the T screw. The chain saw should sound like the one on the file below.
  • Adjust the high revolutions. screw H. If we turn it clockwise the rpm will go up, if we turn it counterclockwise the rpm will go down. We turn it until there is no gap in the ignition. After that turn it back about a fifth of a turn. The sound of the chainsaw when running at maximum rpm should be as you listen to the file below.
  • Checking your chainsaw’s acceleration. It should be able to get it going smoothly and quickly. If the RPMs are slow, then turn the L screw a little.

Remember that the optimal carburetor adjustment is:

Does it need to be disassembled?

To adjust the carburetor chain saw can be generally without any disassembly, in rare exceptions have to remove the air filter cover. Here there is no small amount of contradiction: on the one hand the chainsaw is designed for easy access to the adjustment mechanism and on the other hand it is recommended to address it as seldom as possible.

True, experienced woodcutters and sawyers always carry a flat screwdriver with a long stinger and periodically adjust the carburetor. The reason for this is simple: when the chainsaw is built, its carburetor is fine-tuned for a specific air and fuel composition. It is clear that the conditions on site are not the same as on the bench.

When changing the brand of gasoline or, for example, increasing humidity, an experienced chainsaw user will always tweak the mixture quality for greater performance and less wear on the piston part. But this, we repeat, requires considerable experience with a particular chainsaw and knowledge of the peculiarities of its behavior. In addition the adjustment is incredibly fine. the screws are turned only by 1/10 1/20 of a turn.

Another reason for adjustment is to repair or replace the carburetor. In any case, you should adjust the mixture quality only if the carburetor is known to be in good working order (no debris, no gaskets leaking), the air filter is clean, the spark plug, the clutch and the ignition system are all in order. Otherwise, there is a good chance that the malfunction will be fixed at one point and the adjustment will abruptly become incorrect and the engine will begin to run on wear and tear.

Efficiency of the method

This method of adjustment is effective for those machines that are not equipped with tachometers. But it will work effectively only under the following conditions:

  • the fuel filter is free of mechanical damage and dirt;
  • The exhaust system is not clogged with carbon deposits and allows you to gain high revolutions;
  • the ignition system is fully functional: the spark plug and ignition module ensure stable operation;
  • all the fasteners are in place and screwed all the way in before starting the adjustment, so that you can then start adjusting them from the same positions.

If it was possible to carry out the adjustment of the equipment without a device that measures the speed of the carburetor, then you do not need to do anything else. It is only worthwhile to periodically tighten the screws in the event that they become loose.

To make the adjustment of the carburetor chainsaw, it is not necessary to have at hand a tachometer. With the help of the adjusting elements you can adjust the operation of this device for a long time without going to the service. The main thing is to know how many turns to turn the screws, and in what sequence to do it. Then the chainsaw will not need adjustment for a long time.

Adjustment and tuning features

To learn how to adjust the carburetor on a chainsaw, you should learn to distinguish between three screws (some models have only one).

L and H screws are similar in appearance only, in fact they are different

Each screw has its own letter designation:

  • The “L” is for the low speed setting;
  • “H” is needed to adjust the upper rpm;
  • “T” is needed to adjust the idle speed (models with one screw have only it).

Factory adjustment is optimal, and with the help of screws adjust the operation of the engine in special situations (work associated with different climatic conditions).

The diagram shows the output of the carburetor adjustment screws with the cover closed

A special tool is used to adjust the chainsaw

Only the L and H screws can be adjusted. To increase the RPM, turn the screws clockwise. To lower. counterclockwise. Sequence of use of screws: L. H. T.

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If there are any doubts about the adjustment, it is better to contact a specialist, because the wrong setting can put the engine out of operation.

Adjusting the Husqvarna chain saw

During the break-in period of the Husqvarna 142, 240, 236, 137 and other similar models the carburetor settings are adjusted so that the engine speed is 600-700 lower than normal working speed. If it is not possible to adjust the working frequency by the tachometer, it is not recommended to override the factory settings by the H screw.

It is strictly forbidden to exceed the working RPM on your own. When, after adjusting the carburetor, the chainsaw chain moves at idle speed, then by turning the screw T counterclockwise, you need to stop it.

In order to tune the saw accurately, it should be placed on a flat surface with the bar facing forward. You also need to warm up the engine for at least 12-15 minutes. First of all, determine the highest number of idling speed. To do this you need to turn the L screw on the chain saw clockwise and then counterclockwise. Once the desired frequency has been determined, turn this same screw anticlockwise from 12 to 25% of its full rotation.

The idle speed of this manufacturer’s models is adjusted with the jets with the letter T. To adjust: Turn it clockwise until the chain moves. Then turn easily counter-clockwise until the chain stops moving.

The H chain saw is correctly adjusted only when the saw makes little noise when the throttle is fully depressed and no weight is placed on the saw.

If the saw makes too much noise when working and smokes, then this nozzle must be turned from left to right to adjust.

STIHL and Partner saws

In chain saws STIHL 250, 361, as well as Partner 351, 350 carburetor adjustment is made with the screws H and L by adjusting the proportions of gasoline and air. If you release them, there will be an addition of a large portion of fuel and therefore the rpm will be high, otherwise the opposite will drop.

Idle speed in Partner chain saws is regulated with a screw with the letter T, and in Stihl you usually have to look for the marking LA. The standard setting of the chainsaw is done during the final tests. Generally after such adjustments the percentage of fuel in the working mixture is higher than the percentage of air, which does not correspond to the optimum parameters. But it is necessary to keep them in the first hours of work during the running-in of the device. After that you can adjust the saw yourself, but it will also work well on the factory settings.

But if you decide to adjust it yourself, then the actions need to be performed in this sequence:

  • adjustment of the L screw;
  • then adjust the H nozzle;
  • Then go on to the idle speed setting with the T screw (if your STIHL chain saw is a LA).

First turn the screw L in both directions to find the maximum RPM of the motor. If the point is found, turn the same screw ¼, thus slightly reducing the rpm. If the idle chain continues to run, turn the T-screw (LA) immediately until the chain comes to a complete halt.

After having set the maximum rpm with the H screw, check the engine rpm with the tachometer. In case it does not correspond to the values given in the service book, the setting should be repeated. If at maximum rpm, there is a lot of smoke coming out of the exhaust pipe, the mixture is too rich in fuel; if you hear noises and the engine heats up a lot, it is too lean. Then it is necessary to adjust the idle speed. When properly adjusted, the engine should sound smooth at low rpm and the chain should not move.

How to set the carburetor on your chain saw with your own hands

The chainsaw’s carburetor is set at the factory for optimum fuel and air intake. But they can go haywire during work due to vibration. even a ¼ turn shift of any of the screws can result in serious changes in the fuel-air mixture preparation parameters and it is necessary to adjust the chainsaw carburetor.

There are three screws marked H (High), L (Low) and S for adjusting the chain saw carburettor. the last screw can have other names depending on the brand and manufacturer, e.g. T or LA.

  • H: is responsible for the operation of the main nozzle and regulates the maximum rpm.
  • L: adjusts the idle speed nozzle and lets you set the RPM.
  • S/T/LA: to adjust the throttle speed of the engine.

To know how to properly adjust the carburetor on the chainsaw, you need a technical data sheet. it contains information about the angles of rotation of the adjusting screws. After that you go straight to the adjustment. By the way, here you will need a screwdriver for adjusting the carburetor of a chainsaw or an ordinary flat screwdriver:

  • Place the chainsaw on a flat surface, preferably a table or something similar. IMPORTANT: the chainsaw always has to be positioned so that the bar is pointing in the opposite direction. The engine should be turned off.
  • Use a wrench or screwdriver to unscrew the housing cover fasteners and remove it to reach the carburetor.
  • Remove the air filter that covers the carburetor for the chainsaw. The manufacturer may install a foam padding on top of the carburettor and you have to remove it as well.
  • Now begins the adjustment of the chainsaw carburetor. Screws L and H have to be tightened as far as they will go. Screw them in slowly and carefully so as not to break.
  • Screws on about 1.5 turns unscrew both screws.
  • Start the engine and let it work for about 7-10 minutes, so he warmed up well. on a cold engine carburetor gasoline chainsaw will not work.
  • After the engine has warmed up, set it to run at medium rpm.
  • Slowly begin to turn the idle speed screw counter-clockwise. Crank it until the engine is running smoothly. If the engine starts to stall, you need to continue adjusting the chainsaw carburetor and slowly return the screw clockwise.
adjust, carburetor, chain

After the adjustment of the carburetor chain saw chainsaw Chinese or any other, it is necessary to “drive” the engine at different speeds.

How to remove the carburetor from a chainsaw?

Either the engine doesn’t start or immediately shuts down, most likely the carburetor is clogged and needs to be cleaned. How to Check a Chainsaw Carburetor? You have to disassemble it, there is no other way.

Before cleaning the carburetor on the chainsaw, it is still recommended to check the other assemblies: air and fuel filters, spark plug and muffler. It’s possible that they’re clogged. it’s easier to clean the filter or replace the spark plug than to clean the carburetor on a chainsaw. By the way, it is a problem with the plugs is the reason why the chainsaw shoots into the carburetor. too late ignition leads to the fact that there is an excess of fuel-air mixture, as it does not have time to burn completely.

In case the problem is not eliminated, you will have to remove the carburetor. To do this is very easy:

  • Remove the plastic rear cover. it is held in place by a latch or thread.
  • Dismantle the air filter.
  • With a flat screwdriver you need to pick up the air rods and remove them. There can be two or three tie rods, depending on the model.
  • The carburetor is fastened with two mounts. they are arranged diagonally. It is necessary to unscrew them.
  • Disconnect the gasoline hose, through which the fuel is supplied to the carburetor from the gas tank.

Step by step setup

“Partner 350” is regulated similar to many models of chainsaws.

After production, these chainsaws are set for more mixture than necessary. It should be like this only during the first hours of work.

When the engine is warmed up it is better to change the setting. At idle, turn the T screw counterclockwise until the chain stops, then adjust each in order: L, H,T.

Screw L should be turned counterclockwise ¼ of a turn at the moment when the idle speed begins to have the largest turns.

The H screw is adjusted as follows: warm up the carburetor and turn it counterclockwise by ¼ of a turn. To check if everything is OK, you need a tachometer. The rpm should be the same as the maximum rpm indicated in the chainsaw’s data sheet.

Your actions should cause the engine to immediately accelerate and make a quadruple noise.

The Husqvarna carburetor is adjusted in the same way.

Partner 351 differs only in the fact that his factory settings initially supply the optimal amount of mixture, that is, everything should work correctly at once. But, if necessary, the above instructions will help you set the carburetor correctly.

Adjustment of Ural

The adjustment is a little different in that it should not be carried out at the sharp maximum rpm, but make sure that the chain gained them quickly but smoothly, without shifting on the bar.

In any case, you should take the setting very seriously, because if it’s done incorrectly, it won’t keep your saw with you for a long time. Take care of your tools and if you’re not sure of your abilities, it’s better to take it to a professional.

Any of them, even the sturdy Druzhba, needs attention and care. And then your chainsaw will be your faithful helper for years to come.

Purchasing a chainsaw HUS365 you should be ready that after a month of its use you will not want to deal with any saw other than this one. The reason for this is its reliability, affordability and, most importantly, its ease of use.