How to Adjust a Husqvarna Chainsaw

Husqvarna 240 Carburetor adjustment at home

The first thing to do is to understand the adjustment screws on the Husqvarna 236 chain saw.

The manufacturer has equipped the model in question with 3 screws:

  • The L-screw adjusts the nozzle at low speeds;
  • The H screw is used to adjust the nozzle at higher rpm;
  • The T screw is used to adjust the idle speed operation.

If it is necessary to adjust the fuel, lubricant mixture and air supply, the first 2 elements must be used. By turning them clockwise, it is possible to deplete the mixture and reduce the rpm. By working in reverse order, i.e. unscrewing the elements in the opposite direction, the mixture is enriched and the rpm increases.

The work of the idle speed is adjusted by the third element. Turning it clockwise, the revolutions increase, and to reduce them, the screw is simply turned in the opposite direction.

Technical characteristics of Husqvarna chainsaw 240

The Husqvarna 240 is based on a 2-stroke engine with a carburetor. works on gasoline-oil mixture. Lifetime increased by improvements of crank mechanism and special cylinder coating. 20% better fuel economy thanks to the innovative X-Torq system, which also lowers harmful exhaust emissions. With a roomy fuel tank and low fuel consumption, it extends tool life without stopping for refills.

Otherwise, the saw has these technical specifications:

  • 2 liter capacity. с.;
  • chain pitch is 3/8″;
  • Fuel tank capacity is 300 ml;
  • oil tank. 200 ml;
  • tire length. 40 cm;
  • weight. 4,7 kg.

When adjustment is necessary

The need to adjust the carburetor on a chainsaw is rare. often there are problems with fuel, air or component wear. But sometimes adjustments are necessary:

  • a started engine stops after a few seconds, or fails to start. the cause is too rich mixture;
  • Excessive exhaust, high rpm, increased flow rate. in this case, on the contrary, the mixture is too lean, t. е. not enough air;
  • revolutions are held at the same level after their reduction or increase by the operator. the cause may be a stuck needle valve.

Factors leading to these changes may be the following:

  • Strong vibration damages the protective cap and the adjustment jets unscrew, changing the setting. In this case it is possible to adjust the carburettor on the chainsaw.
  • Worn piston system components. carburetor adjustment in such a situation may help temporarily. Replacement of worn components is recommended.
  • Poor quality fuel, a faulty filter or long storage time can cause clogs. In this situation, the carburetor must be removed, washed with a special liquid or pure gasoline, reassembled and re-adjusted.

The best way to start tuning up your saw is to check the nozzles, fuel and air supply. After that, go to the removal of the carburetor, and then. to check the piston system.

Adjusting the Husqvarna 137 carburetor

The best advice I can give you is to ask a professional! For a small amount of money, the experts will adjust the carburetor, check the overall condition of the saw. If you still need to adjust the carburetor on the Husqvarna 137 without assistance from others, then I will try to carefully outline the process. Also, at the bottom of the post added a video that actually how to adjust the carburetor chain saw at idle speed.

There are three screws to adjust in the picture above. They have their own professional purpose:

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The T screw is needed to adjust the idle speed.

Screw L is used to adjust low rpm.

At first we use the L screw (by turning it) to find the highest rpm at idle speed. If you have found them, you should turn this screw a quarter of a turn against the clock hand. If the circuit is still running, turn the T screw to stop it.

adjust, husqvarna, chainsaw

Then warm the engine at full throttle for about 10-15 seconds and turn the screw H a quarter counterclockwise. Wait 10 seconds and listen, the engine should sound like a 4-stroke. If you hear a squeal, the mixture is lean (turn the screw out), if the smoke is enriched mixture (turn the screw in).

After adjusting the low and high revolutions, set the idle speed with the T screw. We do it this way:

4.5.Turn the T-screw clockwise until the chain starts to rotate.

3.Turn the screw the other way until the chain stops.

With a properly adjusted carburetor, your chain saw has a rapid progression and sounds just like a 4-stroke motor.

adjust, husqvarna, chainsaw

How to adjust the carburetor on a chainsaw

Remember, you need a tachometer and experience to properly adjust your chainsaw carburetor. That’s why it is better to go to a special service!

adjust, husqvarna, chainsaw

Adjusting a chainsaw carburetor allows the tool to operate efficiently at operating power while consuming less fuel. Adjustment should be performed with a clean fuel filter and air filter. For more carburettors adjustment is done with 3 screws: for high and low revs and idle speed adjustment.

Use screws H and L to adjust the ratio of petrol and air consistency determined by the carburettor choke opening. Unscrewing the screws broadens the consistency and the engine rpm will drop accordingly, tightening the screws broadens the consistency and the engine rpm will increase.

The designation H refers to the highest rpm screw that controls the main nozzle, L. to the low speed screw that controls the idle speed nozzle. With the help of the S screw the idle speed is precisely adjusted. From time to time, in order to simplify the option the number of available adjusting screws of the carburetor is reduced.

Setting the carburetor chain saw is divided into two steps. the basic (factory options), carried out when the engine is off. and final, performed on a running warm engine. The exact values of the turning angles are to be found in the instruction manuals for each chain saw. Failure to comply with the manufacturer’s instructions leads to engine damage.

The adjusting screws of high H and low L revolutions slowly turned clockwise at full speed, after which unscrew them backwards by 4.5 turns, other options are also possible

Find the highest idle speed, for this purpose, you slowly turn the screw L in different directions. After finding the high RPM position of the motor you need to turn the L screw 1/4 turn counterclockwise. If the chain still rotates at idle speed the screw T or otherwise (S) should be turned clockwise until it stops.

Checking and Adjusting the Maximum RPM.

The maximum rpm is changed with the screw H. When it is turned in (clockwise rotation) the revolutions go up, when it is turned out. decreases. Chainsaw engines have the highest rpm at 11500 rpm. up to 15,000 rpm. Slightly overspeed is not provided by the ignition, today, it becomes unsafe for the motor. The RPM limit is determined by the ignition interruption. if they come on, the H screw is turned counterclockwise a little.

If the engine is not tested for acceleration and maximum rpm, the chainsaw adjustment is not considered complete.

When you press the trigger smoothly, the engine should confidently and rapidly gain speed from idle to the greatest (from 2800 rpm and above).up to 11500-15000 rpm. depending on the unit). If revolutions are slow and lag behind, it is necessary to turn counter-clockwise slowly, but not less than 1/8 of a turn.

After adjusting the acceleration and maximum rpm check again the idle speed of the saw. the engine should run steadily and the chain should not move. Chainsaw adjustment must be repeated if this condition is not performed however except for the basic adjustment step.

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Most chainsaws carburetors have three screws for adjustment:

  • L. nozzle adjustment screw for low rpm
  • H. nozzle adjustment screw for higher rpm
  • Screw. T at Partner and Husqvarna (at Stihl LA ). the chainsaw‘s idle speed adjustment

Use screws H and L to adjust the petrol/air consistency ratio determined by the carburettor choke opening. When you unscrew the screws, the mixture becomes richer and the rpm increases accordingly, when you tighten the screws, the mixture becomes depleted and the rpm drops.

The chain saw won’t start or won’t start well.Cause and how to fix it

The T(LA) screw is for adjusting the idle speed. The basic adjustments are done at the factory during the final testing of the chainsaw. carburetor, you are adjusted to a richer (than the best) fuel consistency. You need to keep the factory settings for the first hours of operation. Then (not necessarily) the carburetor is adjusted more accurately.

Start with the idle speed option; turn the adjusting screw T (LA) counterclockwise until the chain stops working and the engine rpm is stable.

How to remove the carburetor and whether to do it before adjusting

If the chainsaw has lost rpm or if it runs too high, the carburettor can be adjusted without removing the carburettor.

But if the chainsaw won’t start, the RPMs hang in one place, or it runs unsteadily. Tuning a chainsaw carburetor won’t make a difference. It should be removed for cleaning or replacement of parts. Act in the following order:

  • After unscrewing the retaining clamps, remove the saw’s top cowl.
  • Remove the gasket and part of the air filter by unscrewing the bolts or by releasing the retaining clips.
  • On the right side of the carburetor is the fuel hose. Let’s take it off together with a control rod of air flap.
  • Remove carburettor from retaining hardware.

Disassemble the carburetor according to the instructions supplied with the kit. When disassembling, particular care should be taken to stack the parts on a pre-prepared cloth. Because of the small dimensions, there is a risk of losing components during disassembly and flushing.

All parts obtained in this way are washed in a special liquid, dried and wiped with a lint-free cloth.

Channels, tubes and jets are blown with compressed air, if possible, prewashing them in an ultrasonic bath.

What tool do you need?

First of all, it is necessary to prepare a tool for adjusting the carburetor of a chainsaw. You will need a set of screwdrivers and open-jaw wrenches, a special cleaner that dissolves carbon deposits and debris.

It is better to disassemble on a table or workbench. On a part of the table, lay a clean, preferably light and solid-colored cloth, on which the parts to be removed and the container for washing will be placed. It is optimal if it is an ultrasonic bath.

How to do it right

There are 3 adjusting jets in the construction of the device. The no-load adjustment screw (T) is located on the top of the carburetor. Below there are a pair of fuel adjustment nipples at minimum (L) and maximum (H) rpm, left and right respectively.

The order of adjusting the carburetor on the chain saw Husqvarna following:

  • Warm up within 5 minutes.
  • Turning the L screw, bring the engine to its highest rpm in an unloaded state and bring it back a quarter-turn.
  • Hold the gas pedal button with one hand for 15 seconds. at this time turn the nozzle H to the right until it stops and reaches maximum rpm. Then turn it back a turn and a half or until the engine “squeal” stops.
  • Release the throttle and turn the idle speed screw (T) clockwise until the chain starts to move. After that turn it in the opposite direction until the chain stops moving.

While adjusting it you might get a situation where the chain saw stops. It could be because the jets were turned out too much or the mixture was too rich or too lean.

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If this happens, it is necessary to twist the jets of minimum and maximum revolutions up to the stop. Then turn them back a turn and a half and try to start the saw.

Adjusting the ignition after adjusting the carburetor

If cleaning and adjustment of the carburetor has not corrected the existing problem, it is necessary to check the spark plug and adjust the engine. You should act in the following order:

How to Tune a Carburetor on a Chainsaw! EP 73

  • Unscrew the spark plug and conduct a visual inspection. If it is dry with a light brown soot it can be considered serviceable.
  • If traces of gasoline are found on the spark plug, the carburetor should be re-adjusted. This is because it supplies an excessive amount of fuel to the internal combustion engine, flooding it.
  • If the spark plug looks normal, check the electrical system. First of all, the cable that supplies current to the spark plug. The end is brought a short distance to the cylinder grill and the cord is used to crank the starter. A spark should strike. If it is missing, the cable is checked with a tester and replaced if necessary.
  • If the cable is good, test the ignition coil. If examination does not reveal fried or broken wires, the coil is testered, comparing the data with the accompanying documentation. If deviations are found, the unit is to be replaced with a similar.

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

After replacing the coil block, the gap in the magneto should be adjusted. The gap between the ignition coil and the flywheel should be 0.2 to 0.4 mm. A set of feeler gauges is needed to set the gap, or a foil of suitable thickness can be used. the probe is clamped between the coil and the flywheel when installed and then pulled out.

Adjusting the carburetor with your own hands on the chainsaw

Allows the tool to operate efficiently at full throttle with economical fuel consumption. Adjustment should be done with a clean fuel and air filter. There are three screws to adjust: for maximum, minimum and idle speed.

Screws H and L adjust the ratio of the mixture of gasoline and air, determined by the opening of the carburetor throttle. When the screws loosen, the mixture is enriched, and the turns correspondingly fall, when twisting, the mixture is depleted. RPMs increase.

The designation H refers to the maximum speed screw that controls the main jet, L. refers to the minimum speed propeller that controls the idle jet. With the S screw the idle speed is precisely adjusted. Sometimes the number of carburetor adjustment screws available is reduced to make adjustment easier.

The chain saw carburetor adjustment is divided into two steps. Basic (factory default) settings performed with the engine turned off. and final released on a running hot engine. Exact angular values are to be taken from the instruction manual of the particular chainsaw. The engine may be damaged if the manufacturer’s instructions are not followed.

Headset

This assembly consists of a 15-inch removable guide bar, 0.325-inch pitch cutting chain. A drive sprocket and tensioner are also included. It is possible to install other kits of smaller size, which mainly meet the requirements of the intended purpose.

Chain lubrication prevents overheating and accelerated wear. The system is equipped with an oil pump with adjustable capacity, which receives the operating fluid from an integrated 200 ml reservoir.

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