Adjusting the carburetor of a STIHL fs 38 brushcutter

STIHL Fs 38 carburetor adjustment

The use of gasoline pumps in the works on gardening involves the presence of wear and sometimes breakage of its mechanisms. But because this tool can not be classified as a complex household appliances, all failures are purely mechanical, which can be corrected by your own hands. In some cases, it is enough to make adjustments that return the tool to normal working condition. One such operation is the adjustment of the carburetor in manual mode. The task of the carburetor. Air and fuel need to be mixed before filling the engine. And if the proportions don’t match, the grass trimmer will have visible malfunctions:

The whole process of adjusting the carburetor of a motorcycle race brand involves only debugging the position of the three screws: L. Adjusting the gasoline supply to the braid at low RPM, H. adjusting speed and fuel flow, T. idle. Thus, if it is necessary to configure the carburetor of line 54 gasoline casting or other types of this series, the following steps are performed:

  • Engine warms up (10 minutes is sufficient).
  • Adjust the H screw by turning to the left/right to the maximum idle speed.
  • From the point found, turn it counterclockwise by 1/4 turn, which will set the desired operating position.
  • Mower speed adjustment is the same, turn counterclockwise (speed reduction) and clockwise (speed increase). The position of the maximum stability of the engine in different positions is reached.
  • Screw L is adjusted in the same way, with low revs to maximum.

Therefore, the whole process is done by ear, so you need to buy a tonometer for more successful work. The most accurate tool maintenance is available from Kosa Motors’ technicians, as well as for the purchase of compressor oil and the purchase of all necessary parts and components for timely maintenance.

Why do I need to adjust the carburetor?? 55

STIHL petrol grass trimmer cuts out when the throttle is on full throttle. CAUSES OF DISEASES !

Adjusting the carburetor for grass trimmer STIHL FS 55 in the video performs to adjust the idle speed

Working with a series of gasoline trimmers foreshadows their active use, because the performance of this device is not limited to leveling lawns. As a result, the engine does not run properly and carburetor adjustment 55 with the introduction of simple manipulation. The resulting irregularities are unpleasant and promise low performance or waste on fuel consumed in large quantities. You should think about adjusting the carburetor grass trimmer in cases where:

  • Unexplained engine stoppages appear after it is started;
  • During operation, the 250 Series braid engine, through an untuned feed mechanism, “roars” under load.
  • Operation is accompanied by an increase in exhaust fumes.

In any case, each cause is the mixing of air and gasoline, where the tuning of the carburetor model 130 will avoid unexpected stops of the engine in the middle of work. Professional gasoline 130 system with rigid drive shaft provides fast cutting of wood, which will stifle the engine if there is a lack of air in the fuel. On the other hand, a tuned 38 ruler or model 450 grass trimmer mixer will not spill gasoline under applied weights when there is often a shortage of air in the carburetor. At Kosa Motors, you can buy all the components for motorists, find out information about installations, and buy a spark plug wrench and other replacement parts for successful repairs.

A little about the manufacturer

STIHL is the name of a group of companies involved in the development, production and sales of agricultural, forestry and construction machinery. One of these companies is VIKING, which produces gardening tools. Founded in 1926 in Weiblingen-Neustadt, Germany.

The products are sold through our own sales and service network of 32 distribution and marketing subsidiaries and around 35,000. Worldwide dealerships. In 1971 the chain saws under this trademark became the best-selling chainsaws on the planet. All continents, except Antarctica, have agencies all over the world. STIHL is always focused on the customer and this has translated into success. Company slogan: “A chain saw is only as good as its servicing” was defined by its founder Andreas STIHL.

“Made by STIHL” on the product label assures you of reliable products and service. According to many developments, the company holds a leading position among manufacturers of such equipment. All implemented innovations are aimed at improving the comfort, safety, functionality and environmental friendliness of products manufactured under this brand. Recognized by customers in more than 160 countries.

adjusting, carburetor, stihl, brushcutter

How to choose the right garden shredder: shredder for branches and grass

Tools for grass mowing

A great number of various tools are designed for grassland treatment. Choosing such equipment, you need to get acquainted with the range of products. The company STIHL has the following types of gasoline machines:

  • FS 38, FS 45 C-E, FS 50 C-E, FS55, FS.
  • Powerful models FS 70 C-E, FS 94 RC-E, FS 100, FS 120, FS 130, FS.
  • battery-powered grass shredders.
  • Running from the mains.
  • Trimmers.
  • Grasshopper mowers.

Gasoline grass trimmers of this brand are very popular. Choosing equipment, you need to know all the features of a particular model.

Lawn mower carburetor housing

Lawn mower carburetor base. duralumin housing. It contains a diffuser (hole with internal circuits). The air is forced through this port. The speed of oxygen (air) delivery depends on the section (orifice) of the diffuser.

Fuel lines are routed through the diffuser. How to adjust the carburetor on the brushcutter carburetor adjustment in practice. video. Airflow draws fuel from them.

Adjusting the carburetor STIHL FS 55 lawnmower

Adjusting the carburettor on a STIHL lawn mower

FS 55 Parts Shop

The fuel is sucked into the carburetor system by the pump (its diaphragm). Trimmer carburetor Then passes through the fitting in the carburetor. The fluid travels on through the inlet and outlet valves of the pump. is filtered by membrane chamber. Fuel flows through the needle valve into the diaphragm chamber.

  • Air is fed through a tube with an air baffle (damper). A baffle plate controls the intensity of the air flow.
  • The fuel system is inevitably narrowed by a mixer to speed up the flow.
  • Gasoline through the float chamber and nozzle tube with constriction. Float chamber controls temporary volume of petrol. In the float chamber the pressure level is neutral, but in the tube with constriction, the pressure level is already low. Fuel oozes through the nozzle through the pressure differential.
  • Acceleration of air flow promotes the transfer of fuel (gasoline) and its atomization. Finally an air-fuel mixture of required density or proportion appears.
  • The air-fuel mixture enters the engine cylinder through the fuel tube.

READ STIHL 250 Carburetor Adjustment Video

The area of the open air damper depends on the level of air density in the system. The wider the choke is open, the higher the fuel capacity.

Simply speaking, adjusting the carburetor on a gasoline mower is about creating a good fuel consistency by correcting the airflow.

How to adjust the carburettor on a chain saw

Before adjusting, the filters must be thoroughly cleaned according to the maintenance instructions.

Further adjustment of the lawnmower carburetor with their own hands is performed by the adjusting screws. There are three of them in total:

The right screw (L) is for adjusting the fuel mixture for low revolutions.

Find the maximum idle speed. To do this, slowly turn the screw (L) to the right and left.

How to adjust the carburettor on a STIHL 55 trimmer.

For adjustment turn the screw a quarter of a turn, always counterclockwise.

Bottom (T). responsible for adjusting the engine at idle.

Proper adjustment of idle stroke is characterized by

  • stable operation of the cold engine;
  • Do not overrun the hot engine revolutions;
  • for the trimmer head a large RPM margin;
  • stable motor operation during changes of position (sudden raising or lowering of the blade).

Left (N). adjustment of the mixture at high revolutions. (The screw is the last one to be adjusted).

The left screw (H) determines the overall adjustment of maximum rpm, engine power, temperature and gasoline consumption.

Adjustment carburetor mower with the last screw is done as follows:

  • Open the throttle to full throttle while giving full throttle. Turn screw clockwise until rpm drops (in this case, guided by hearing).
  • Turn the screw as slowly as possible counterclockwise until the engine is uneven.
  • Then turn back just a little bit, hardly having heard a stable, smooth work.
  • For a clearer application of skills it is more convenient to look at the work of an experienced user:

It is interesting that from the point of view of the author of the video, adjustment (its correctness) is defined by color of a spark plug, and not only by revolutions and engine stability.

The correct setting of the carburetor with their own hands in this case. the combustion of the fuel mixture without residue, the color of the candle should be light brown.

Quickly starting the lawnmower: tips

Some people pull the handle with such force that they have to make repairs to the starter lawnmower with their own hands. This is only possible if the cable is torn or the cable handle is broken. In other cases, it is recommended that the starter motor be replaced. The assembly is sold as a complete unit.

Lawnmower carburetor adjustment and repair

trimmer for grass to complex household equipment does not apply, because most of his breakdowns are of a mechanical nature and quite successfully eliminated with their own hands. Even if the motor fails for severe reasons. damage to the piston ring, for example, the repair comes down to replacing the part.

The carburetor is relatively simple to operate and needs some adjustment.


The STIHL FS 55 petrol grass trimmer and ride-on mower is a lightweight, mobile grass trimmer with plenty of power. Indispensable for mowing meadow and decorative grass, when mowing undulating or rugged terrain. This unit efficiently shines over soft grass and clears thickets of bushes or overgrown grass with the same efficiency. The small bar enables mowing in hard-to-reach places: along the house wall, around bushes, posts, benches.

  • STIHL FS 55 petrol grass trimmer and ride-on mower. Model advantages
  • STIHL FS 55 gasoline grass trimmer/ lawnmower. Model specifications
  • Running in the STIHL FS 55 petrol grass trimmer/ lawnmower. User manual

STIHL FS 55 petrol grass trimmer / lawnmower. Model advantages

  • Ergonomic two-handled handle in silver color. Fits well in the hand, does not slip out when working.
  • Handlebar-mounted motor control. To make it safer to use.
  • Replaceable cutting attachment increases the functionality of the machine. The STIHL FS 55 petrol/diesel trimmer comes complete with a disc for hard and overgrown grass and a disc for trimming bushes.
  • Eye protection goggles. Gives direct and lateral protection, radiates on the inside, does not create a greenhouse effect of windows, gives a good panoramic view.
  • STIHL shoulder strap. Comfortable use of the trimmer increases productivity, reduces energy loss, distributes the load evenly, no shoulder pressure. Keeps hands free for productive mowing, holds the brushcutter securely in place during operation.
  • The tank is made of semi-transparent material, which allows the operator to visually monitor the fuel level.
  • Fuel consumption is controlled by special system. Gas-saving t-handle design ensures low fuel consumption and minimal exhaust emissions.
  • Easy trimmer operation. No particular knowledge or experience required. The buttons on the handle are marked with standard symbols and are self-explanatory for the user.
  • No electric drive. The chain saw works anywhere in a large area without mains power.

STIHL FS 55 gasoline grass trimmer / lawnmower. Model Technical Description

  • Total weight 5 kg.
  • Power output 1.1 л.С.
  • Straight-line boom design.
  • T-handle design.
  • Cutting tools trimmer line, metal disc.
  • Maximum permissible mowing area up to 1000 m2.

Test drive of the STIHL FS 55 petrol grass trimmer/ lawnmower. User manual

The grass trimmer requires a running-in period to operate properly and for a long time afterwards. The running-in period warms up the moving parts, increases the initial resistance in the drive train and lightly wears parts down to reduce this resistance. The Running-in Process is also a great opportunity for the beginner to learn how to control the trimmer.

  • Before starting work prepare a fuel mix of the recommended oil and gasoline specified in the data sheet. Mix the fuel mix in approx.5 liter AI.95 add 100 grams of STIHL oil in the red package. A plastic container made of plastic resistant to aggressive liquids or an aluminum tank should be used for mixing. An ordinary canister is always with rusty micro-parts, accumulating in the carburetor of the saw, rust leads to clogging and failure of the assembly.
  • Total running-in time is 3 to 4 hours. During this period, it is not advisable to run the tool for more than 15 minutes at idle speed. Continuous starting up for 20-30 seconds is necessary.
  • You can combine a running-in period with light-duty tasks, e.g. mowing non-rigid material.
  • Once in half a year bring the tool with a warranty period to the service center for technical inspection and carburetor adjustment.

Special features of operation

Every STIHL lawnmower is designed precisely for the intended purpose, taking into account engine power. The manufacturer expressly recommends against any unauthorized additions or improvements to the brushcutter. Before you buy a STIHL lawn mower, it is important to understand what you have to do.

It would not be a good idea to buy a powerful trimmer for occasional lawn mowing.

When operating it is important to:

  • Work/rest intervals of 20 minutes.
  • Use only high-quality gasoline that does not exceed Ai-92.
  • Use original STIHL engine oil (50:1) for the fuel mixture.
  • You should not operate the engine until it has been run-in for 2 to 3 full loads.
  • To reduce the risk of engine damage, always remove any gasoline residue from the fuel tank before storing the brushcutter for the winter or before taking a break in service.
  • Check the fuel filter regularly. clean it or replace it with a new one. to ensure proper operation.
  • To prevent serious malfunctions, you must avoid clogging the air filter.
  • Observe the safety precautions for your STIHL lawnmower.
adjusting, carburetor, stihl, brushcutter

The STIHL brushcutters are designed for long life and trouble-free operation, as long as you pay attention to the advice in the operating manual.

Special features

Every STIHL brushcutter is designed precisely for the intended use, depending on engine power. The manufacturer strongly recommends against self-adjustment or any kind of upgrading of the STIHL grass trimmer. So before you buy a STIHL lawn mower, it’s important to know what you’re working on.

Do not buy a large grass trimmer for the occasional lawn mowing. a light gasoline mower or electric mower may be adequate.

The important thing is to:

  • Working and resting at 20 minute intervals.
  • Use quality gasoline not lower than AI-92.
  • Use original STIHL engine oil (50:1) for the fuel mix.
  • When running-in the engine up to 2-3 full fills of fuel, do not operate the engine at maximum load.
  • If you leave the STIHL brushcutter in the winter or if you don’t intend to use it for a while, always drain the gasoline from the fuel tank to avoid damage to the engine.
  • To ensure a stable operation, the fuel filter should be inspected regularly. cleaned or replaced.
  • To prevent serious malfunctions, the air filter must not get clogged.
  • Follow the safety precautions for your STIHL ride-on mower.

STIHL brushcutters are designed to provide long, trouble-free cutting performance by following the instruction manual as closely as possible.

Weaknesses of trimmers and chain saws

STIHL brushcutters are renowned for their reliability. Unlike many other brands, they are equipped with a quality motor, cutting lines and top-quality construction. However, a long service life without the need for replacement parts is only possible if your STIHL brushcutter is serviced regularly:

  • Inspecting and cleaning the machine;
  • Disassemble the machine and remove the soot from the internal parts;
  • Replacement of worn parts;
  • New lubrication.

If this is not done, the STIHL FS 38 weed trimmer carburetor will soon need repair because the engine parts cannot tolerate a lack of lubrication or unsuitable fuel.

Gasoline tool breakdowns and their signs

These are not all the reasons why you need a STIHL 38 grass trimmer repair. But these faults are solely the fault of the user and occur in 85% of cases.

Important! Some problems are hard to pinpoint and require diagnosis by yourself.

For this procedure, experts use technical equipment available only in service centers. On your own to find the cause of the breakage will take up to 3-4 weeks.

How to correctly replace a spark plug?

As you can see, there is nothing very complicated about this procedure.

A new spark plug for the two-stroke internal combustion engine of the gasoline grasshopper is installed to replace the old part that has failed

Starter malfunctions

The starter in a chain saw fails in these situations:

To repair, the starter unit must be disassembled and the faulty part replaced. If the belt spring breaks, it must be replaced.

Damaged cord should also be replaced with a new one. In the case of a displacement of the tape spring (out of engagement with the pulley), it should be returned to its original position, which will require a certain force.

Sometimes the drive cord gets caught on the shaft, as a result of which not only tears, but also damages the starter housing. In such a situation, the assembly is not repairable, it must be replaced with a new one.

Instructions for users

Any gasoline-powered tool needs a pre-run-in phase before use. At this time, the moving parts are lapped to reduce resistance. Since this stage takes place at low revolutions, it is easier for a beginner to master such equipment.

Before starting work, the mixture must be prepared. Its parameters and the materials used are listed in the technical documentation for the product. It looks something like this: 2.5 liters of 95-grade gasoline mixed with 100 grams of STIHL oil from the red package. This procedure must be performed in a container that is resistant to aggressive liquids. A simple metal canister is not suitable because of the rusty areas that can not be detected inside. Corrosion particles entering the carburetor, clogging it, which leads to failure of the part.

During the warranty period, the lawnmower needs maintenance and adjustment of the carburetor. To have your mower serviced by an authorized service center.

Pros and cons of the model:

Naturally, the list of positive points should include the veracity of the brand itself.

  • Necessity to constantly check the fuel level;
  • A small motor life;
  • Low capacity;
  • Expensive;
  • meager equipment.

The presence of not particularly disastrous shortcomings of the model does not have a negative impact on the popularity of the unit, because there is simply no perfect technique.