Adjusting a chainsaw carburetor

Today we will talk about how to adjust the carburetor on a chainsaw. You do not know how to adjust the carburetor on a chainsaw yourself? Next, we’ll point out some helpful tips on how you can do it yourself.

But if you have no time, or do not do it yourself can not, then you can contact us in the “Rem Tech Service” Call by phone: 063-202-90-70 or 097-023-42-42. Our experienced specialists will gladly suggest how to adjust the carburetor on a chainsaw, or do it themselves in a very short time.

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

So, in more detail, how to adjust the carburetor on the chainsaw

There are three screws for adjusting the carburetor on chainsaws. One bolt is identified by a letter. T, that is, the stroke, it adjusts the idle speed on the chainsaw. Also, there are two more bolts that are designed to adjust the fuel supply, they are designated by English letters. L (little) idle and H (hot) hot load. First of all you need these bolts after the disassembly, assembly of the carburetor, cleaning, it is necessary to screw in to the stop and then the bolt marked buva. L, unscrew it by 2.5 full turns, and the bolt. which. H ( fuel supply under load) unscrew by 1.25, or 1.5 turns. this is the factory default setting.Then try to start the saw and with the biggest screw adjust the idle speed marked with the letter. T. After these manipulations, your chain saw will work either at high RPM or will idle and idle will start to stall, which is why the two bolts L and H have to be adjusted.

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

After you have regulated the normal, stable idle run, you should give the chainsaw a chance to reach the maximum rpm (it should run smoothly and steadily).

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

You don’t know how to tune the carburetor on your chainsaw, and how to properly adjust the carburetor on your chainsaw? Contact us at our service center, and we will help you promptly cope with the problem, and what is important at affordable prices. Call us or leave a request on our website.

Adjusting the carburetor of the STIHL MS 250 chain saw (with RPM meter):

Before adjusting the carburetor on your STIHL chain saw, carry out service (clean the carburetor, clean the engine, replace the spark plug, clean the air filter, check the chain tension, adjust the idle speed, warm up the engine).

Turn the H and L screws (on a stopped chainsaw) until they stop and then turn them both out a full turn. 2. Start the chain saw and let it warm up. Full throttle and turn the “H” screw to get the maximum engine speed of 14000 rpm. watch the tachometer (engine revolution counter). Hold the maximum rpm for no more than 10 seconds for adjustment! 3. Use the “LA” bolt of the idle speed stop to make the chain start moving and then turn it ¼ turn counterclockwise. 4. If, after this adjustment of the chainsaw carburetor, the idle speed is not stable and the chainsaw accelerates badly, then it is necessary to turn the screw “L” a little counterclockwise until the chainsaw will quickly gain speed and work well at idle speed. Then adjust the screw “LA” (idle RPM should be 2800 RPM according to the tachometer).

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Note: You can not adjust the carburetor of a chainsaw if there is air leakage into the engine from the side (through the gasket under the carburetor, through the gas pedal pump of the carburetor, through the crankshaft glands of a chainsaw or somewhere else).

When do you need to adjust the settings at all??

Specifically adjustment of the chainsaw carburetor is required in rare cases, more often there are problems related to the flow of fuel or wear and tear of parts. But sometimes the “symptoms” are an indication that the mechanism needs adjustment. Here are some signs:

  • After the engine starts, it immediately cuts out. Alternatively, it may not start at all. This is due to an oversaturation of air and a shortage of fuel.
  • Increases in fuel consumption and therefore a high level of exhaust emissions. This is due to the opposite process. oversaturation of the mixture with fuel.

Causes of adjustment failure can also be mechanical:

  • The safety guard is damaged by heavy vibration and as a result all three bolts loose their hold.
  • Due to wear and tear on the piston part of the engine. In this case, adjustment of the carburetor chainsaw will help only temporarily, it is better to replace the worn part.
  • Due to clogging, which occurs due to poor-quality fuel, scale or damage to the filter. The carburetor needs to be completely disassembled, flushed and adjusted.

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

Adjusting the carburetor of a chainsaw with their own hands

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

Use the H and L screws to adjust the gasoline/air mixture ratio as determined by the carburetor throttle opening. untightening of screws enriches the mixture and correspondingly lowers revolutions, tightening tightens the mixture. revolutions increase.

The designation H refers to the maximum rpm screw that controls the main nozzle, L. L designation refers to the low RPM screw that controls the idle speed restrictor. Use the S screw to fine tune the idle speed. Sometimes, to simplify adjustment, the number of available carburetor adjustment screws is reduced.

Setting up the chainsaw carburettor is divided into two steps. the basic (factory setting), which is carried out with the engine turned off. and the final, made on a running warm engine. The exact value of the angle of rotation should be taken from the instruction manual for the particular chainsaw. the maximum speed screw that controls the idle speed restrictor.

Maximal RPM H and minimal RPM L revolutions adjustment screws should be slowly turned clockwise up to the stop and then turned back two revolutions

Find the highest idle speed by slowly turning the L screw in different directions. After finding the position of the highest engine speed, you must turn the L screw 1/4 turn counterclockwise. If the circuit is rotating at idle speed, the T or (S) screw should be turned counterclockwise until it.

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Check and adjust maximum rpm.

Change the maximum rpm with the screw H. If it is turned clockwise (clockwise rotation), RPM increases, if it is turned counterclockwise, RPM decreases. decrease. Chainsaw engines have the highest rpm between 11500 rpm. to 15000 rpm. A higher speed does not provide ignition, moreover, it becomes dangerous for the engine. Limit revolutions can be determined by the ignition interruption. if so, turn screw H slightly anticlockwise.

If the running of the engine is not checked for acceleration and maximum rpm, the adjustment of the chainsaw cannot be considered complete.

adjust, idle, speed, chainsaw

When smoothly pulling the gas pedal trigger, the engine should quickly and surely gain speed from idle to maximum rpm (2800 rpm and higher).up to 11500-15000 rpm depending on the machine). If the revolutions are slow and lag behind, the screw “L” should be turned slowly anticlockwise, but not more than by 1/8 of a turn.

After adjusting the acceleration and maximum rpm check again the idle speed of the machine. the engine should run steadily, the chain should not move. Chainsaw tuning must be repeated if this condition is not met, but except for the basic tuning step.

Setting the factory setting for the nozzles.

Slowly turn back the screws “H” and “L”. Then turn in the opposite direction by two revolutions. For the exact number of revolutions refer to the instruction manual.

Find and set the maximum rpm by slowly turning the “L” in different directions. When the maximum rpm is set, turn the L jets counterclockwise by 1/4 of a turn.

If the chain is still moving at idle speed turn the small adjustment screw “S” anticlockwise until the chain stops moving.

When is it necessary to adjust your chainsaw carburetor??

Here’s a list of the most common cases in which you need to adjust your chainsaw carburetor:

  • The engine starts but the chain saw stalls or fails to start. the reason may 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. The mixture must be of the right quality to keep the engine running properly.
  • Screws in the carburettor have lost their fixation due to a damaged carburettor body.
  • Debris in the carburetor. This can happen if the filter is damaged or low-quality fuel is used. You will need to completely disassemble the carburettor, rinse it and readjust it.
  • The engine does not idle or does not develop full power.

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

How to rebuild the carburettor

Any model has three tuning screws. Do idling, high and low revolutions with their help. To set the parameters you need, turn these screws correctly.

Before you adjust the carburetor of chain saw, it is mandatory to read the technical documentation for the tool to understand all the design features of the model. The manual shows how to position the adjusting screws.

adjust, idle, speed, chainsaw

Electronic tachometer will help you to fine tune the gasoline saw. The complete conditioning procedure includes the following steps:

Chainsaw Carburetor Adjustment | How to Tune ‘Correctly’. by Craig Kirkman

  • Base adjustment of carburetor on chainsaw. This is done by turning the high and low revolutions. First you need to twist them behind the shank up to the stop, then two times in a clockwise direction.
  • Testing of idle speed is started by turning the respective twist to the position where the idle speed is highest. A tachometer will help you to find these indicators. Then turn the low revolution screw one-quarter turns against the governor shaft. If there is rotation of the lance, turn the idle screw against the throttle trigger until it stops.
  • The high revolution screw is used for setting the maximum revolutions. If you twist it, torque increases, if you twist it, torque decreases. On most models the maximum rpm are from 11500 to 15000 rpm. Exceeding the admissible quantity may cause ignition failure.
  • To check the acceleration, you need to press the start button of the tool. The motor will then very quickly increase the number of revolutions. If the gauges are increasing steadily, tighten the low revolution screw 1/8.
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After all the adjustment steps are done, check how the tool operates at idle speed. If the engine works well and the valve is not damaged, it means that the adjustment was performed correctly. If the motor does not work properly and in case of a loss of the lance, the motor must be controlled again but without the basic step.

Carburetor adjustment

Exact work should be done only when the engine is hot. So start the engine and warm it up for 10 hvillyns. Then turn the adjusting screw against the throttle trigger to stop the engine.

Before adjusting the carburettor, lay the tool on a level hard surface. Keep the adjusting screws “H” and “L” in the direction nonhazardous. Do not place objects close to the cutting edges of the tool.

To regulate the carburetor operation, three screws are used, each of them has its own designation:

  • H. Control the master switch designed for tuning the upper wraps.
  • L. Controls idle speed restrictor, recommended for low revs.
  • Т. adjustment of idle speed.

Adjustment is done with screws “H” and “L”. To reduce the octane number of the gasoline saw the regulators are turned from the left to the right (behind the engine barrel). This procedure is designed to increase engine RPM. To increase the octane number the gears rotate in the opposite direction, from right to left. Thus, the speed is set to low.

The sequence of regulation is as follows: L → H → T.

Cranking up to the maximum of screw “L”, from left to right or in the opposite direction you find the limit number of wrapping. Then we turn back to ¼ of a revolution.

When the engine is hot, proceed in the same way with the “H” screw. Allow the chainsaw to run for a few seconds. Using a tachometer or a good ear, read the maximum rotational speed by the sound. It must correspond to the values defined in the equipment data sheet.

If the lever is in the neutral position when idling, turn the knob “T” in the same direction until it stops completely.

Please note that if the regulator “H” does not set the revolutions point accurately, the engine will fail and will require expensive and time-consuming repair. The idle speed is controlled with the “T” screw. Turn the knob against the mainspring (right to left) until the flange comes to a complete stop.

If the carburettor is properly regulated you should be able to see this:

We hope that our article has helped you to solve such a problem, as in the regulation of the carburetor chainsaw, and you will be able to carry out self-treatment. If in the process of corriguing you have arise doubts, it is better to entrust this process to the staff of specialized service center, where there are all the necessary components for the repair of machinery.

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