Dismantling And Assembling the gas trimmer Carburetor

Necessary special tool:

  • Special screwdrivers.

When disassembling the carburetor, special screwdrivers, shown in the figure and in the table, should be used to unscrew the fuel nozzles of the main dosing systems and air nozzles of the idle systems, in order to avoid damage to the threads of the channels and slots of the nozzles.

Dismantling And Assembling the Benzotrimmer Carburetor

Table. The main dimensions of special screwdrivers for disassembling the carburetor K-126P

Name of carburetor part Screwdriver Dimensions, mm
d l s
Idle air jet 6.5 6 0.8
Main fuel jet 8.5 8.2 1
Auxiliary valve 10 9 1,6

The sequence of operations:

  1. Unscrew strainer plug and remove filter.
  2. Disconnect the link connecting the levers on the axes of the air and throttle valves, for which remove the cotter pin from the upper bent end of the link.
  3. Remove the screws that secure the upper and middle parts of the carburetor; remove the upper part and the gasket.
  4. Take out the axis of the float and remove the float.
  5. Remove needle valve with damping spring. Release needle valve housing.
  6. Unscrew idle fuel jets.
  7. Unscrew plugs covering idle air nozzle ducts and unscrew nozzles.
  8. Unscrew the air jets of the main metering systems.
  9. Release emulsion tube wells and remove emulsion tubes.
  10. Unscrew plugs that allow access to main fuel jets and unscrew jets.
  11. Unscrew the fuel-conducting screw and the screw that secures the spray gun housing of the accelerator pump and additional system; remove spray gun housing and gasket. Carefully turning the carburetor body, remove the pressure valve of the accelerator pump from the channel.
  12. Remove the four screws securing the bottom of the carburetor to the middle. Separate the lower part of the carburetor while simultaneously pressing on the drive bar of the accelerator pump and remove the earring connecting the lever of the throttle axis to the rod of the drive of the accelerator pump.
  13. Remove the accelerator pump drive stem with the bar and piston and remove the rod return spring. Remove the inlet valve safety ring from the accelerator pump well and, turning the body of the float chamber, remove the inlet valve. Release valve for auxiliary system.
  14. Remove idle adjustment screw from carburetor mixing chamber.
  15. Bend the edge of the lock washer on the throttle axis and unscrew the nut that secures the throttle actuator forks; remove the fork and the intermediate lever from the axis. Release two screws securing the cover of the rocker mechanism of the throttle actuator of the secondary chamber and remove the cover.
  16. In case of emergency (for example, when replacing the throttle return springs), the throttle axis is dismantled in the following sequence:
    • A) unscrew the nut of fastening of the accelerator pump drive lever on the throttle axis, remove the washer and lever;
    • B) unscrew the two screws securing the throttle on the axis, remove the valves and remove the axle with spring from the housing of the mixing chambers.
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    The axis of the throttle of the secondary chamber is dismantled in the same way. Subsequent installation of throttle valves with axles is carried out in the reverse order. After installing and fixing the throttle valves on their axes, the screws must be loosened.

    All disassembled carburetor parts must be thoroughly washed with gasoline.

    In the presence of abundant tarry deposits on the parts, they can be washed with acetone or thinner.

    It is absolutely unacceptable to use wire, even if soft, to clean the jets. With this method of cleaning, the calibration of the nozzles is inevitable. The consequence of this will be a deterioration in the traction of the car and an increase in the operating consumption of gasoline. The washed parts and carburetor channels must then be purged with compressed air.

    The carburetor is assembled in the reverse order. In this case, it is necessary:

    1. Inspect the gaskets installed between the upper and middle and between the middle and lower parts of the carburetor. Replace damaged gaskets with new ones.
    2. Check the valve of the accessory system for leaks and if it seizes in the seat guide. Check if the piston of the booster pump moves easily in the cylinder. It should move in the cylinder without jamming.
    3. Check, with the throttle fully open, the clearance between the adjusting nuts (valve stem of the auxiliary system valve and the piston rod of the accelerator pump) and the drive bar. On the piston rod of the accelerator pump, this clearance should be 1 mm, on the valve stem 15 mm.
    4. When installing large diffusers, fuel and air jets, both main dosing systems and idle systems, in both chambers of the carburetor, one should strictly follow the technical data of the carburetor.
    5. When wrapping plugs covering the carburetor channels (drain, etc.), pay attention to the presence and quality of their fiber gaskets. Damaged gaskets replaced.
    6. Check the tightness of the needle valve for the fuel supply and make sure that when there is no load, the damping spring 2 of the needle valve 3 extends 0.7-1.3 mm above the end of the rod.
    7. Check the float before installing it in the cover of the float chamber for leaks. If soldering the float is necessary, take appropriate precautions to prevent the explosion of gasoline vapors. After soldering, maintain the weight of the float within 13.3 ± 0.7 g.
    8. Check the position of the float relative to the needle valve. To do this, turn the cover 1 of the float chamber 180 ° and, slightly pressing the float 5 with your finger, measure the distance from the top surface of the float to the plane of the cover with the cardboard lining removed. This distance should be 42 ± 0.4 mm and controlled by a special template. If necessary, the correct position of the float can be restored by appropriate bending of the tab 4 of the lever of the float in the direction from the lever.

    Video: Dismantling And Assembling the gas trimmer Carburetor


    Suburban construction and repair can not do without the use of a chainsaw, as well as garden care. Due to a malfunction of the tool, all the work can get up, so it is so important to be able to disassemble it yourself, find problems and fix them. With enough experience and dexterity, even adjusting the carburetor of the chainsaw is possible – the procedure is complex, or rather, jewelry. How to carry out adjustment procedures, we suggest that you take apart today.

    Chainsaw carburetor device

    Not a single repair measure is complete without knowledge of the fundamentals of the mechanism. Understanding the components and the principle of operation, it is easier to determine the cause of the breakdown.

    Any malfunction in the carburetor threatens to stop the engine

    The carburetor is one of the main functional parts of the engine, which serves to prepare and supply the fuel mixture, consisting of certain proportions of fuel and air. As soon as the proportions are violated – the engine begins to "junk", or even completely stops working.

    You can achieve the correct operation of the carburetor by examining its "filling":

    • Tube with transverse flap for adjusting air flow.
    • Diffuser – constriction to increase the air flow rate, located near the fuel inlet.
    • The atomizer from which the fuel is supplied (fuel needle in the diagram).
    • A float chamber that controls the fuel level at the entrance to the channel.

    Here’s how it looks in the diagram:

    The diagram shows the interaction of fuel and air flow

    Principle of operation: the air stream in the diffuser atomizes the fuel, creating a mixture entering the cylinder. The greater the amount of incoming fuel, the higher the engine speed. Carburetors of various models work according to the same scheme.

    When is adjustment necessary at all?

    Specifically, adjusting the carburetor of a chainsaw is required in rare cases, more often there are problems associated with fuel intake or wear of parts. But sometimes “symptoms” indicate that it is necessary to regulate the mechanism. Here are some signs:

    • After the engine starts, it immediately stalls. As an option – it won’t start at all. The reason is an excess of air and a shortage of fuel.
    • Increased fuel consumption, and as a result – a large amount of exhaust gas. This is due to the reverse process – supersaturation of the mixture with fuel.

    The reasons for the failure of adjustment can be mechanical:

    • Due to strong vibration, the protective cap is damaged, as a result, all three bolts lose their installed fixation.
    • Due to wear on the piston of the engine. In this case, setting up the carburetor of the chainsaw will help out only for a while, it is better to replace the worn part.
    • Due to clogging caused by low-quality fuel, scale or damage to the filter. The carburetor requires complete disassembly, flushing and adjustment.
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    If the chainsaw suddenly stops working, it is necessary to disassemble it to find out the reasons.

    Step-by-step disassembly instructions

    The carburetor device of models of different brands is almost the same, so let’s take the Partner chainsaw as an example. Each element is carefully removed and stacked in order, so that later it is easier to assemble.

    Carburetors of chainsaws from different manufacturers, if they differ, then not fundamentally

    The top cover is removed by unscrewing the three bolts. Following it is foam rubber, an integral part of the air filter.

    The arrows indicate the bolts that must be unscrewed to remove the cover

    Then we remove the fuel hose, followed by the drive rod.

    The upper arrow indicates the fuel hose, the lower arrow indicates the drive rod.

    Next, remove the cable tip.

    The arrow shows the tip of the cable to be removed.

    To the left of the fitting we tighten the gas hose.

    We also carefully remove the gas hose indicated by the arrow

    The carburetor is finally disconnected, it is ready for adjustment. Its mechanism is quite complicated, therefore, if further disassembly of the carburetor is required, the elements should be removed very carefully – they are small, therefore they can be lost.

    The carburetor consists of many small parts that, when disassembled, should be laid out in order

    Features of adjustment and adjustment

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

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

    Each screw has its own letter designation:

    • “L” is used to set low revs;
    • "H" is needed to adjust the upper revs;
    • "T" is needed to adjust the idle speed (only one screw is present on models with one screw).

    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 outputs of the carburetor adjustment screws with the lid closed

    A special tool is used to set up the chainsaw

    The adjustment is carried out only with screws L and N. To increase the speed, they are rotated clockwise. To lower – counterclockwise. The sequence of use of the screws: L – H – T.

    If you have doubts about the adjustment, it is better to consult a specialist, as improper tuning can damage the engine.