Chainsaw partner 350 DIY carburetor repair

In detail: chainsaw partner 350 do-it-yourself carburetor repair from a real master for the site my.housecope.com.

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.

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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.

Video (click to play).

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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 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.

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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:

  1. Always mix gasoline and oil in accordance with the manufacturer's numbers. Image - Chainsaw partner 350 DIY carburetor repair The proportions of the fuel mixture for the chainsaw engine
  2. 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.
  3. 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.
  4. 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.

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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.

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Chainsaw carburetor operation diagram

Carburetor settings can be affected by:

  • lack of fixing the adjusting screws; Image - Chainsaw partner 350 DIY carburetor repair Chainsaw adjusting screws
  • wear of the piston group; Image - Chainsaw partner 350 DIY carburetor repair New CPG chainsaw Husqvarna 365
  • blockage of the fuel-air channels;
  • damage to air filters; Image - Chainsaw partner 350 DIY carburetor repair Chainsaw air filter with nylon insert
  • poor quality gasoline or oil.

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.

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Carburetor set correctly - saw starts the first time
  1. Arbitrary changes in engine power

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.

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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.

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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.

Image - Chainsaw partner 350 DIY carburetor repair

Chainsaw carburetor repair tool

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

  1. To get to the carburetor, you need to remove the top cover of the chainsaw, which is fixed with three bolts. Image - Chainsaw partner 350 DIY carburetor repair Removing the carburetor cover
  2. 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.
  3. 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. Image - Chainsaw partner 350 DIY carburetor repair Removing the fuel hose and drive rod
  4. After removing the hose and rod, remove the throttle cable tip from the fixing socket and finally dismantle the gasoline hose. Image - Chainsaw partner 350 DIY carburetor repair Removing the throttle cable
  5. The carburetor can then be removed from the mountings for later disassembly. Image - Chainsaw partner 350 DIY carburetor repair 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. Image - Chainsaw partner 350 DIY carburetor repair 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 of a turn to the left, then let the engine run for 10 s to 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. Image - Chainsaw partner 350 DIY carburetor repair 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.

Among the huge selection of models on the modern construction market, the Partner 350 chainsaw stands out, which is produced by a subsidiary of Husqvarna.

General view of the Partner 350 chainsaw

Simple and easy to use, reliable and unpretentious, this saw has gained wide popularity among summer residents and owners of country houses. Sawing firewood, pruning trees and branches - this is not the whole list of works that this model will cope with without problems.Despite the well-thought-out design and layout of the units, over time, wear of the power unit, transmission elements and fuel system occurs.

Experienced fellers know that a competent and accurate determination of the nature of a breakdown is half of the repair work done. Based on many years of experience in repairing the partner 350 chainsaw, specialists have developed a special method for diagnosing problems.

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Major chainsaw breakdowns Partner 350

It should start from the simplest nodes and mechanisms, ending with more complex ones.

This allows you to significantly save time and avoid unnecessary operations. Troubleshooting is recommended in the following order:

  1. Chainsaw spark check;
  2. Ignition coil;
  3. Diagnostics of the fuel supply system;
  4. Inspection of the crankshaft bearings.

To diagnose the presence of a spark, it is necessary to remove the candle and, without removing the high-voltage cable, make several jerks with the starter. If there is a discharge, you will need to set the gap between the central and side electrodes. Its value in Partner 350 should not protrude beyond 0.7 to 1.2 mm.

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Adjusting the spark plug gap with a feeler gauge

Failure to reach this distance can lead to incomplete combustion of the fuel mixture and, as a consequence, increased fuel consumption with limited power of the unit. As a result of exceeding this parameter, there is an inconsistency in the occurrence of a spark and interruptions in the operation of the internal combustion engine.

If there is no spark on the electrodes, it is necessary to replace the spark plug and repeat the diagnostic manipulation described above.

If no discharge is observed on the replacement spark plug, it is necessary to check the integrity of the high-voltage wire and, if necessary, replace it.

The absence of a bright blue spark in the plug may indicate the need to inspect the ignition module and adjust the gap. For these purposes, we remove the plastic protective cover from the saw and check the condition of the coil. The wires leading to it must be firmly fixed with screws; they must not dangle at the connection point. Moisture must not be present on the flywheel of the drive shaft as it interferes with the generation of an electromagnetic field.

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Flywheel and ignition module of the Partner 350 chainsaw

In the absence of such inconsistencies, you must make sure that the clearance between the module and the flywheel is correct. Its value should be no more and no less than 0.2 mm, and therefore, if it does not coincide with the recommended distance, you need to independently adjust the ignition of the Partner 350 chainsaw.

For the most accurate adjustment, you need a regular coin-shaped or flat probe, which you can buy in specialized or automotive stores.

After checking the ignition, proceed to the diagnosis of the fuel supply system.

An important influence on the correct operation of the saw is played by the fuel system, which consists of a gas tank, pipes and a carburetor.

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Carburetor Partner 350 disassembled

If the mixture does not flow from the tank, it is necessary to inspect the built-in filter and breather (hole in the lid). If the fuel filter becomes clogged, it will need to be replaced. To clean the breather, you can use an ordinary sharp needle, carefully removing the remnants of dirt and sawdust from the valve. If the carburetor becomes clogged, it will need to be dismantled and thoroughly cleaned.

It must be remembered that the partner chainsaw carburetor is a complex assembly consisting of many small parts. Therefore, when dismantling, cleaning and assembling, maximum attention is required.

The carburetor is used to mix the fuel mixture (oil and gasoline) with air. Its work begins with the jerk of the saw starter, which forces the membrane to pump fuel. After that, a diaphragm-controlled needle valve supplies gasoline to the main chamber, through which it enters the cylinder. The throttle valve can be used to "enrich" or "lean" the fuel mixture with air.When it is closed, less air will flow into the cylinder at the same fuel level. In this case, consumption will increase, coupled with a decrease in engine power. Therefore, the adjustment of the Partner 350 chainsaw plays an important role in creating an optimal balance of moderate fuel consumption with high tool performance.

It is recommended to make self-tuning only if you have special tools and skills.

Before starting adjustment work, it is necessary to clean the main fuel unit from dust and dirt. To do this, you can use a compressor with compressed air or a broom brush.

To adjust the carburetor, holes are provided on the left side of the power unit, however, for the convenience of determining their position, experts recommend dismantling the protective plastic casing. First, turn the screws of the fuel quantity and quality fully clockwise until they stop, loosening them after 1/5 ... ¼ turn.

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Partner 350 chainsaw carburetor with adjustment screws

When the cover is removed, you need to know that the screw for the quality of the fuel mixture is on the right and, accordingly, the screw for adjusting the amount of gasoline is on the left. For convenience, the carburetor body is marked under the bolts:

- "L" - screw for the amount of fuel (adjustment at low speed);

- "H" - screw of the amount of the mixture (setting at maximum speed);

- "T" - idle speed adjustment bolt.

It must be remembered that the adjustment of the carburetor of the Partner 350 chainsaw must be carried out on a warm engine. At high temperatures, the metal expands linearly, as a result of which the throughput of the channels increases.

As soon as the cylinder becomes warm, turn the screw "L" until the internal combustion engine produces the maximum crankshaft speed. Then we twist it a quarter of a turn. It is worth noting that in this position, the screw for the amount of supply of the mixture should support the operation of the motor at idle. If such a setting is not enough, then boldly unscrew the “T” bolt until the engine runs stable. Using the screw "H" we correct the work of the Partner chainsaw at maximum speed.