Chainsaw carburetor design and adjustment

The carburetor is one of the most important components of any modern chainsaw. Its main task is to mix the fuel mixture with air, as well as the further delivery of the finished fuel into the cylinder of the gasoline engine. During the use of a chainsaw its carburetor is constantly working, so over time, this node begins to need adjustment and flushing. To perform these procedures is simple enough, if you are very careful and follow the correct order of.

Almost all carburetors used in chainsaws have the same mechanism. Only the mechanisms with which Chinese garden tools are equipped make the difference.

As standard, the fuel assembly consists of the following parts:

  • Float chamber. this element is designed to continuously maintain the required amount of fuel. When the assembly operates, the fuel is transferred to the atomizer through the built-in nozzle;
  • tube. fuel flows into the carburetor chamber in portions through the tube. The fuel supply is regulated by the position of the built-in factory shutter;
  • atomizer. this detail is necessary for injection of fuel into the intake air stream.

The principle of operation of a chainsaw carburetor is quite simple. During operation of the assembly, air is drawn in by a tube and passes through it at a speed that is regulated by the built-in flapper. When the choke opens, the float in the chamber is actuated. After passing through the diffuser, the air is mixed with the fuel and atomized instantaneously. The air-enriched, high-quality fuel mixture then passes through the intake manifold and enters the engine cylinder. You can visually see how a carburetor works in the diagram.

Fuel circulates in the node under pressure. In the float chamber, it is close to atmospheric air, but in the standard suction tube, it is more rarefied. Thanks to the difference in pressure that is formed, the fuel mixture enters the tube. The higher the amount of fuel, the higher the RPMs a chainsaw‘s engine is capable of generating.

How to adjust the carburetor of a chainsaw. Chainsaw Maintenance. Part 11

In this video we will answer the question how to tune or adjust the carburetor of a chainsaw with your own hands.

Carburetor. is a part of the engine power system, the main purpose of which is to prepare the fuel mixture.

Today we’re going to level out the idle speed of a chainsaw.

Says Stepan LatypovDirector of the enterprise Belarbo Building Knowledge Base

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How to tension the chain on a chainsaw, Husqvarna and STIHL.

Hello! On my 361, the chain at idle and then does not rotate about 50 \50.I need to get the revs down? And another question about the bar and chain.There are 0.325 pitch chains; there are 3\8. There is a 1.3 thick (if I understand correctly), there is a 1.5. Will I be able to put another thickness of chain on the bar instead of one and what will happen? I counted the links in my saw and bought a chain with the same number of links! Didn’t even think about the thickness.And where is it on the package??

Hello, what do you need to adjust if after releasing the throttle button the chain keeps spinning for another five seconds.?

Good evening, I’m new to sawing trees. I just had the carburetor tuned. In principle, it works great if you saw a log diameter of 20-25 cm, cut itself and goes like clockwork. But if you saw a log with a diameter greater than 30-cm and a little pressure on the saw, the chain stops. Is it because the carburetor is not set correctly or just not enough power to the saw? A 2 horsepower saw with a 40 cm tire.

Hello, watched your video went to adjust the STIHL 180 carburetor chainsaw but there is only one screw how to do ?

Hello. My saw, which is a MC 180 high idle turns the chain, the adjustment screw is fully turned, help me understand the reason. The saw starts fine, though. Thanks for the video tutorials very helpful.

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Absolutely! To make one eyebrow higher than the other when adjusting! For the importance of procession!))))

That’s clear. But how do I get the saw to come back quickly after a load?? I think you should turn down the H screw ? I already told you the problem)

Good evening! Can you please tell me about the adjustment of all 3 screws on the carburetor. All the settings have been messed up and can not adjust. Jonsered 2041 Turbo

Tell me, I bought the saw and it was working fine. But then the chain started spinning without pushing the throttle, before a little bit of chain spinning without pushing the throttle, now at full throttle! I haven’t turned it, I haven’t twirled it, tell me what to do? I don’t know much about it, what could it be??

Hi. I need some advice. McCulloch 340 saw, the band and carburette are from Husqvarna 236. Came to me like this, won’t start. Inspection and as a result of changing the group. Now it starts but does not hold load, I mean, the chain is off and the saw is working. I know there could be a lot of reasons to narrow it down. The group on the sealant, the boys are good, the only thing between the cylinder and carb on the sealant may have closed a hole? The most obvious causes removed (fuel, fuel-in leaks, etc.).ะด). Screws do not turn, but I am not sure that the first owner did not turn, tell me L H how much where?? Thanks.

Good evening! My chainsaw stalls after starting (won’t run on dry running), if I start it up and press the gas immediately, it starts but once I release the gas, it shuts down. What could be the problem (filters are clean)?

There are two nozzles on the carb of the chainsaw for the fuel.For what it is necessary and where it is better to put the hose from the gas tank.

Hi watch the video and tell me if you have to do it or not?

Hello! How do I adjust the Goodluck 4500 to be a little more efficient? it eats gasoline like water.

My chain spins on its own after starting the saw. I have to press the gas briefly and it stops. It should be? Either something needs to be adjusted?

Chainsaw Attitude/Idle Adjustment

Stepan, everything is clear. But it’s better not to tell people about these screws, they will screw the wrong one in any case))))

STIHL 360 in cold conditions and only starts when I put oil in the cylinder.But when it is hot it starts fine.What does this mean? low compression?

what does the idle speed and carburetor adjustment have to do with it? idle speed is a far cry from adjusting the fuel/air mixture.

Hello. My idle speed is fine. The problem is in a different way: You start sawing a bundle of humpback logs, you just slightly press the saw and the tire stops, as if not enough power at full throttle, while the gas is not stopped, but stupid as a tire stuck. The chain’s dry, no dull chain. Almost new. As a result, I saw some way almost without pushing, the flour is wild. Any tips? It’s true the saw is almost 10 years old. Bicor bbp 2340. I ain’t done nothin in it but cleaned spark plug and air cap.

Worked in Yakutia.62 not a single saw works only the Stihl 180, and wrapped with mullet and duct tape.

Idle began to drop and the chainsaw “on top” stalled. Spin the blanks, and you will be happy)))) What a pain in the ass for these wizards. Explain to me how the idle speed adjustment and “stalled at the top” are related.

The quality of mixture at the carburetor outlet

Directly in the carburetor is a working mixture, the composition of which can be adjusted in quite a range of operating adjustments. When the engine works with an enriched mixture the fuel does not burn completely which reduces traction and the engine burns fuel with lower efficiency.

Poor mixture combustion is characterized by engine overheating, loss of power, deterioration of lubricating properties of the oil component of the fuel mixture, appearance of detonation phenomena unsafe for the power unit structure.

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Factory default settings are based on average values and do not take ambient conditions such as air pressure, temperature and load conditions into account.

Periodic adjusting of the gasoline-air emulsion composition allows maintaining the traction characteristics of the power train at a given level and stabilizing the economical fuel and engine oil consumption regime.

Adjusting the carburetor on a STIHL STIHL 180 chain saw.

There is only one adjusting screw for adjusting the carburetor on the STIHL STIHL 180 chain saw. the no-load adjustment screw.

Standard idle speed adjustment (abbreviated as x.ั….): turn screw counterclockwise until it is tight, then make two revolutions clockwise and that’s it. 2. If the rpm is too low x.ั…., then turn the screw clockwise until the chain starts to move and then turn it another 0.5 turns counterclockwise. 3. If rpm is too high x.ั…., If it is too low then turn the screw counterclockwise until the chain stops turning and then turn it another 0.5 turns counterclockwise.

That’s it, adjustment of the carburetor on the STIHL 180 chain saw is complete.

To adjust the carburetor on your chain saw

Adjusting the chainsaw carburetor allows the tool to operate efficiently at full power with economical fuel consumption. Adjustment should be performed with a clean fuel and air filter. For more carburetors adjustment is done with three screws: maximum, minimum and idle speed adjustment.

The H and L screws adjust the gasoline/air mixture ratio determined by the carburettor choke opening. When loosening the screws the mixture is enriched and rpm drops correspondingly, when tightening the screws the mixture is depleted. rpm increases.

The designation H refers to the maximum rpm screw that controls the main nozzle, L. to the minimum RPM screw that controls the idle speed nozzle. The idle speed is fine-tuned by means of the S screw. Sometimes, to simplify adjustment, the number of available adjusting screws on the carburetor is reduced.

Setting up the carburetor of a chainsaw is divided into two steps. the basic (factory settings), carried out with the engine turned off. and final, performed with the engine running warm. The exact value of the rotation angles should be taken from the instruction manual of the particular chainsaw. Failure to follow the manufacturer’s instructions may result in damage to the engine.

adjust, idle, speed, chainsaw

The maximum H and minimum L rpm setting screws should be turned slowly clockwise as far as they will go and then turned back two revolutions

adjust, idle, speed, chainsaw

to find the highest idling speed, turn slowly the L screw in different directions. After finding the highest rpm position, turn the L screw a 1/4 turn counterclockwise. If the chain still rotates at idle speed, turn the screw T or (S) clockwise until it stops.

Checking and adjusting maximum rpm.

Change of maximum rpm is done with the screw H. When turning it in (clockwise rotation) the rpm increases, when turning it out. decrease. Chainsaw engines have the highest rotational speed from 11500 rpm. up to 15000 rpm. A higher speed is not provided by the ignition, moreover, it becomes dangerous for the engine. Limit revolutions can be determined by the ignition interruption. If this occurs, turn the screw H slightly anticlockwise.

If the engine is not tested for acceleration and maximum rpm, the tuning of the chain saw is not finished.

adjust, idle, speed, chainsaw

When smoothly pulling on the throttle trigger the engine should go from idle to maximum rpm (2800 rpm or more) quickly and surely.up to 11500-15000 rpm depending on the machine). If rpm comes on slowly, with a lag, the screw L should be turned slowly counter-clockwise, but not more than 1/8 of a turn.

After adjusting the acceleration and maximum RPM, the idle speed of the saw should be checked again. the engine should run steadily, the chain should not move. The saw adjustment must be repeated if this condition is not fulfilled but with the exception of the basic adjustment step.

Adjusting and checking the maximum rpm.

Adjust the maximum engine speed with the “H” nozzle. The RPM increases as the “H” screw is turned in. Gasoline saws have a speed ranging from 11,500 rpm to 15,000 rpm.

The highest revolutions are determined by the occurrence of interruptions in the ignition system of the saw’s engine. If they are found, turn the “H” nozzle slightly anticlockwise.

When a chainsaw carburetor adjustment is necessary?

Here’s a list of the most common cases in which a chainsaw carburetor adjustment is needed:

  • The engine starts but the chain saw stalls or fails to start. The cause could be too much air in the fuel chamber.
  • Increased fuel consumption. It can occur due to excessive saturation of the mixture that enters the engine with fuel. For the engine to run well, the mixture must be of the right quality.
  • Bolts in the carburetor have lost their fixation due to a damaged carburetor housing.
  • Debris in carburetor. This can occur if the filter is damaged or if low-quality fuel is used. You will need to completely disassemble the carburetor, wash it and readjust.
  • The engine does not work well at idle or does not develop the full power.

Important! If the engine doesn’t run well because the piston is worn out, adjusting the carburetor will not work. In addition, it is desirable to clean the carburetor from debris along with the tuning. this will increase the efficiency of the procedure.

Adjusting the carburetor of a chainsaw

Today we will talk about how to adjust the carburetor on a chainsaw. You don’t know how to tune the carburetor on your chainsaw yourself? Next, we will introduce useful tips on how you can do it on your own.

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But if you do not have time, or you can not do it yourself, then you can contact us at “Rem Tech Service” Call us by phone: 063-202-90-70 or 097-023-42-42. Our experienced specialists will be happy to advise you on how to properly adjust the carburetor on a chainsaw, or do it themselves in a very short time.

The principle of operation of all carburetors is absolutely the same, although they may differ slightly in appearance, but they all work the same. The principle of a chainsaw carburetor is no exception, also the same.

So, in details, how to adjust the carburetor on a chainsaw

There are three adjustment screws that adjust the carburetor on chainsaws. One bolt is designated by the letter. T, that is, the tact, it regulates the frequency of idling on the chainsaw. Also, there are two more bolts that are designed to adjust the fuel supply, they are denoted by English letters. L (little) at idle and H (hot) load hot. First of all, you need these bolts after disassembly, assembly of the carburetor, cleaning, it is necessary to screw to the stop and then the bolt marked with a bead. L, unscrew to 2.5 turns full, and the bolt. which. H (fuel supply under load) unscrew to 1.25, or 1.5 turns. these are standard factory settings.Then try to start the saw and with the largest screw adjust the idle speed marked with the letter. T. After these manipulations, your chain saw will work either at high RPM, or vice versa will start to stall at idle, for this you need to make adjustments with these two bolts L and H.

If the engine speed is too high, unscrew the L bolt half a revolution or a full revolution, depending on the condition of your piston group and the way the engine draws in the fuel.

After you have set the idle speed to normal and stable, let the chainsaw reach its maximum rpm (it should be running smoothly and steadily).

Also, it is recommended to try to saw off something with it, because under load, it can behave, let’s say, not quite adequately. To do this, there is a bolt that is marked with the letter H, in case the saw stalls and does not develop full power, then you need to unscrew the bolt to 0.25 or half a turn, and then try again (this bolt adjusts the fuel supply under load).

You do not know how to adjust the carburetor on a chain saw, and how to properly adjust the carburetor on the chain saw? Contact us at our service center and we will help you to promptly cope with the problem, and what is important at affordable prices. Call us or leave a request on our site.

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