Adjusting the carburetor of the Huter bs 52 chain saw
Adjusting the carburetor of Chinese Husqvarna chainsaw
Under atmospheric pressure, the air after going through the preliminary purification enters the narrow part of the tube, where its flow is regulated by the choke. This is also where the air becomes discharged and the resulting vacuum draws combustible fluid from the fuel line. A special needle connected to the nozzle chamber is used to adjust the fuel flow rate. The quality of the fuel mixture is regulated with the help of the choke. when the air is opened, more fuel begins to flow into the carburetor and the power of the power plant increases.
To avoid problems with the work of the tool, it is necessary to periodically adjust the chainsaw. When too much air enters the mixture, it becomes depleted, and engine power decreases. The lack of air also negatively affects the operation of the unit, because the fuel consumption increases. At the same time, it does not burn completely, which leads to the appearance of soot on the walls of the cylinders. It is quite obvious that the question of how to adjust the carburetor on a chainsaw, many owners of this tool ask.
First, however, it is worth noting the signs of a quality power plant:
- RPMs are quickly gained.
- The sound when the engine is running is similar to a four-stroke.
- No cranking is observed when the engine is idling.
The carburetor’s purpose, design and principle of operation.
The carburettor is needed to prepare the air-fuel mixture for feeding the engine. If the proportions in this mixture are not correct, the engine malfunctions. If the proportion is not correct, the mixture is called oversaturated, but if the fuel is low, the mixture is called lean. Both have a bad effect on engine operation.
In different models of chainsaws carburetors differ in design, but in principle they are similar. The air moves at high velocity through the air duct. The choke, which closes the channel, allows you to change the speed of the air jet. the fuel is pumped through the nozzle into the channel, where it mixes with the incoming air and forms an air-fuel mixture. The resulting mixture is fed to the engine.
The pressure in the float chamber, where the fuel is before mixing, is almost equal to atmospheric. But a vacuum is created in the air duct, so the fuel is drawn into the air flow. The more the choke is opened, the faster the air travels and the fuel quantity also increases. the engine speed rises. This is a simplified representation of the carburetor principle.
Adjusting the chainsaw’s carburetor is necessary for efficient, smooth operation, maximum output, and economical fuel consumption. Check the fuel and air filters before adjustment. they must be clean. On most chainsaws the adjustment is made with three screws: idle, high rpm, low rpm. The following signs are indicative of the carburetor’s proper tuning:
- No movement of the chain at idle speed.
- The engine accelerates smoothly and quickly.
- The sound of the engine is smooth, like a four-stroke engine.
How to adjust the carburetor on a chainsaw
Care must be taken when adjusting the carburetor, because mistakes in adjustment can have very serious consequences, up to and including engine malfunction. If you are not absolutely sure, call a service center.
When adjustment is needed
Modern “three-screw” Carver chain saw carburetors are not designed for manual adjustment at home. Screws are factory-set and are locked against rotation from vibration by clinging springs, so they don’t turn freely.
But the screws on the carburetors of Carver chain saws can be adjusted through special holes without removing the cover, with a simple screwdriver. This suggests that these models are designed from time to time need to adjust the carburetor.
The reason for this cannot be determined from a technical point of view. Only versions are possible:
- Carver chainsaw carburetor is in the zone of high vibration, because of that the screws untwist spontaneously.
- A coarse spring is installed, which cannot fix the screw, as on other models.
- Periodic adjustment is required because of the technical characteristics of the carburetor and the Carver chainsaw engine in general.
Repair of carburetor with your own hands
That the carburetor needs repair can be determined by the following signs: unstable operation of the motor, excessive fuel consumption, spikes in engine power, pops.
Huter chainsaw is not considered a complex tool for disassembly, so if you have the initial skills of a mechanic. mechanic, improvised tools and the desire to make a replacement parts yourself will not be difficult.
What can be replaced in the carburetor without going to a specialist:
- fuel filter (flush or replace). when engine jerks and sneezes;
- Needle valve. if the needle is jammed in the valve or stuck;
- fuel pump diaphragm. wear
- the gasket under the main chamber cover. leakage.
- Disassemble and flush the carburetor if the air filter is clogged;
- tighten the bolts if they are loose due to intensive vibration of the chainsaw.
Walbro company produces extended repair kits for self-replacement, which include almost all carburetor parts (fuel inlet needle, rocker, rocker axle, filter screens, diaphragm).
Important recommendation to avoid carburetor malfunction: do not leave fuel mixture in non-operating saw more than 12 hours, such negligence could lead to clogging of channels.
How to adjust the carburetor of a chainsaw without a tachometer
Such equipment requires tachometer adjustment. If you improperly adjust the carburetor on equipment without a tachometer, the chainsaw can quickly fail. However, you can also tune the saw if you don’t have a measuring device. Here’s a step-by-step guide to setting up your chainsaw.
Screws tightening and loosening
In the device of the chainsaw carburetor there are adjusting elements of different classification. This can be adjusted with a standard screwdriver. There are three of these items in total:
- H screw. Required to adjust the maximum speed of the equipment;
- T screw. Responsible for the idle speed setting;
- L screw. Adjusts the chain saw’s low RPM.
Turning each screw changes the setting. First you need to tighten the screws H and L until they are fully seated, but not too much, and then gently unscrew them two turns, no more. Screw T goes all the way in without loosening.
Starting the chainsaw
After the initial settings are made the machine should be started. After that loosen the idle speed screw and the spindle adjustment knob a little to make the chainsaw work steadily. In case of low idle, turn screw T.
Check for acceleration
When you increase the speed of the equipment, the stroke should not fall off. If there is a problem with this setting you should adjust the RPM dropping by turning the L screw.
RPM drop moment
The last step is to catch the torque drop. You can do this by adjusting the screw H. But it’s important to watch how you turn it, you don’t want to overdo it
To do this, you need to squeeze the throttle to maximum power and twist this element. The next step is to catch the moment of overfuel and a drop in rpm to start cranking the propeller harder. This lets you correctly adjust the saw without a tachometer in terms of RPM. Once these have been set the chainsaw can be operated.
Types of faults and troubleshooting
If you do not start the Chinese chainsaw or it works, but not effectively, with interruptions, make a diagnosis to accurately identify the cause before disassembling the tool and looking for parts to replace.
If the engine is silent after starting the starter mechanism, the cause may lie in:
- malfunctions of the main engine components (improper fuel supply or exhaust, problem with the ignition system, with the cylinder and its piston group);
- Faulty lubrication system, chain brake mechanism, problems with the clutch (its clutch) to the tire, etc.д.
These same causes can lead to these “symptoms”:
- engine stalls a couple of minutes after starting;
- the main unit is working irregularly;
- the engine only runs well at idle, and when you increase the RPM it stalls, dramatically losing power.
Faulty ignition system
When the Chinese chainsaw stalls, inspect the spark plug. If it is completely dry, it is an indication that no fuel has entered the cylinder, so the cause of the tool malfunction should be sought in another node. If the candle is filled with oil, it is necessary to carry out adjustment of the carburetor.
You should also clean the spark plug thoroughly, cut off the fuel supply, ventilate the chamber after removing traces of fuel, and then start the starter system. When the spark plug is installed in place, check the engine.
If you notice black fouling, change the oil to a quality one, or adjust the ratio of the consumables. In this case also conduct cleaning of the spark plug (in some cases a needle or awl is needed), as well as stripping it with an electrode skin.
When you put the spark plug back in place, don’t forget to set the electrode gap correctly. The optimal width is 0.5 millimeters.
Important! In some cases, a new spark plug is needed, but before that check for spark presence using a method that is convenient for you.
Fuel system malfunction
There may be several reasons for this problem:
- Contaminated fuel filter. It is easy to identify the cause by inspecting the fuel system after removing the hose. A weak fuel jet indicates the necessity of cleaning the fuel filter. If cleaning did not help, a new hose is installed in this node.
- The breather plug installed on the tank lid is clogged. Use a needle of proper diameter to clean it.
- The fuel mixture is too rich. It helps to cope with this problem again, cleaning the fuel filter.
- Improper carburetor adjustment. It is possible to adjust it yourself, based on the instructions provided in the operating manual of your power unit.
Defective chainsaw muffler
This problem is indicated by disabling the engine in operating mode (the engine works fine at idle speed). Check the spark plug which can be cleaned of fuel mixture combustion products. To do so remove the silencer and seal its seat with a clean rag. Remove the soot from the muffler with detergents. Before installing this part, it is thoroughly dried.
If your chainsaw doesn’t run or runs erratically, perhaps this article will help you. why the spark plugs on your chainsaw are pouring? The problem is common on Chinese tools.
A faulty cylinder and its piston group
You can suspect a problem when the engine is not running at full throttle. It may also fail to start as little pressure is generated in the cylinder. In order to accurately identify the cause of the malfunction, check the crankshaft bearings, the cylinder pistons, the cylinder itself. All of these parts can wear out. To examine such parts of this assembly, first remove the muffler. The overview will be limited, but it is enough to understand the condition of certain parts.
Faulty chain lubrication system
- Oil leaks, you will notice with the naked eye. In this case it will be necessary to check the connection point of the pump tube and its connector. Cracks in the oil pump and housing may be the cause of the problem. The malfunction can be corrected by replacing the tube and sealant.
- Insufficient oil supply, which can be preceded by clogging of the lubricant supply channels. You can solve the problem by cleaning them.
- Cracks in oil pump, its body. Only replacement can help.
Broken chain brake system
Brake system may malfunction or not function at all, causing problems with powertrain operation due to a clogged surface hidden under a protective cover. Another possible cause is a worn brake band. The tape can be replaced and if it’s clogged you have to clean it thoroughly.
In order to encounter various problems in the operation of the saw less often, check the different parts of the device for wear, including the anti-vibration unit, the guide rail, all the sprockets, including the main.
Adjusting the carburetor of a chainsaw on the example of Huter BS 45
It should be noted that during the manufacture of Huter chainsaws, the carburetor is not precisely factory-adjusted due to the fact that the test conditions of air and fuel composition differ from the conditions in the real mode of operation.
Therefore, in most cases, the carburetor needs a more thorough adjustment, immediately after the initial running-in.
Which carburetor is installed on the Huter BS 45 chainsaw?
As written above, this model of the line of chainsaws Huter is equipped with a membrane carburetor firm Walbro. The advantage of such a carburetor lies in the ability to dose the quality and quantity of fuel mixture, as well as, in contrast to the float carburetors, the ability to work in any position.
Design and operating principle of the carburetor
The carburetor is one of the most important parts of a chainsaw and is used to mix fuel with air and deliver this mixture into the engine combustion chamber.
For self-tuning a Huter carburetor, it is important to know how it is built and understand its principle of operation.
Walbro carburetors are simple to set up. Have a monobloc through-hole type housing. Inside the hole there is a diffuser. narrowing of the passage with a fuel injection channel. On both sides there are sliders: the smaller one is a throttle valve, it regulates the amount of fuel mixture to be supplied to the cylinder. A larger flap. air, serves to limit the flow of air during a cold start.
Scheme of the carburetor chainsaw Huter BS-45
In the engine cylinder, a vacuum is created and a diaphragm pump doses fuel into the carburetor chamber through a diaphragm pump channel by deflection of the control diaphragm and moving a needle to the lower position. Valves and flaps open due to the difference in pressure, thereby letting in and directing these elements through channels to the diffuser, where air and fuel mix, atomize and enter the engine cylinder.
What you need for adjustment
Before you start adjusting the carburetor, you should prepare the necessary tools, materials and instruments that will be useful in the process.
You can buy them in specialized stores.
Electronic tachometer for adjusting engine speed
How to adjust. step by step algorithm
Adjusting the carburetor of a Huter chainsaw is done with the help of three adjusting screws
- L. adjustment of low revolutions (responsible for fuel quality);
- H. adjustment of high revolutions (responsible for the amount of fuel);
- T. adjustment of idle speed.
Location of the adjustment screws on the carburetor Huter In the same order should perform the adjustment.
Remember that the tool must be plugged. Remove dirt and dust in the carburetor area. Place the saw on a stable surface, point the chain away from you and begin making adjustments.
- After turning the L screw all the way in, use a screwdriver to loosen it by 2.5 turns.
- Turn the screw H, also turned in advance up to the stop, 2.5 turns.
- Start the saw and warm it up for 5-10 minutes.
- After warming up the saw, slowly turn the screw L clockwise (turning the screw in this direction will deplete the fuel, resulting in an increase in RPM), using the tachometer you should find the maximum engine RPM at idle and then release the screw 1/4 turn, counterclockwise.
- Adjust the maximum engine rpm with screw H following the principle described above.
- Next, on the T screw, adjust the idle speed (counterclockwise). Set it so that the engine runs steadily, without noise, and until the saw chain stops moving when idling (if it is rotating).
- Re-start the saw and check that it runs smoothly without any smoke or squeal.
It is important to know that the adjustment of the carburetor is carried out only after a complete diagnosis of the saw, excluded, troubleshooting of other parts of the chainsaw (air and gasoline filter, spark plug, gasket between the engine and carburetor).
The gasket, which connects the engine and carburetor of chainsaw Huter very often fails (shrinks, cracks), in the place of the defect begins air leakage (mix is depleted, then enriched), resulting in a stable operation (the saw starts floating, loses power, lagging occurs).
When to regulate by yourself and when it is better to give in the service center
It is possible to adjust the carburetor yourself if you have an idea of its working principle, and exactly follow the sequence of the adjustment algorithm. If after the adjustment at home, the stability in the work of the chain saw has not been achieved, you should contact a specialist to avoid irreparable damage to your chain saw Huter.
Adjusting the carburetor of a Chinese chainsaw with your own hands
Not all carburetors of Chinese chainsaws have an adjustment procedure. Today there are many models of domestic class chainsaws, including European brands, on the carburetors which regulating screws simply do not. Or there is only one idle speed adjustment screw.
Such carburetors only need adjustment when the chainsaw idles and emits too little and sometimes stops. The following text will discuss the algorithm for adjusting the idle speed of the carburetor on the Chinese chainsaw.
A screwdriver suitable for the slots of the adjusting screws is needed for adjustment. On different carburetors they may be flat, Phillips, with an internal or external hex, star, etc.п.
Adjustment algorithm for a carburetor
Before adjusting you should make sure that it is necessary. All Chinese carburetors, on every chainsaw have a factory setting, which is knocked down very rarely. Adjustments may require adjustment of a new carburetor, or in rare cases, an old carburetor.
The cause of engine deterioration with signs similar to poor fuel mixture, in most cases, are:
If this is not the problem, try adjusting the carburetor.
Engine must be warm. A cold engine works differently when warmed up to operating temperature. Therefore, adjustment will not be correct when the engine is cold.
- Open the access to the adjusting screws. On some chainsaws it is sufficient to remove the cover and the air cleaner. On others, it is necessary to remove a part of the housing. On some of them there are holes in the housing for a screwdriver.
- There are screws marked T (or LA) L and H on the carburetor or near the holes. Screw T (or LA) is for idle speed adjustment. Always located away from the L and H screws, which are next to each other.
- If the chainsaw stalls when turning on the gas. the engine doesn’t have enough fuel to rev up. Adjust the fuel rate with the H screw (main screw). unscrew it by 1/4 turn and throttle up. If the engine became better, unscrew another 1/4 turn. (If worse, turn it 1/4 turn in the opposite direction).
- if the engine starts to run like at idle it means there is too much fuel, turn back the H screw.
- Check peak rpm by ear or tachometer. The maximum rpm for each chainsaw is given in the manual. (10,000. 12,500 rpm). In practice 10,000-11,000 rpm in the “full throttle” position is normal.
- increase the amount of fuel with the screw H and correct the quality of the fuel mixture with the screw L. It increases and decreases the amount of air in the mixture. If there is not enough air, the fuel will not burn out, and as a result, the engine smokes, does not develop power, and consumes extra fuel. The L turnscrew also affects engine operation at low and medium rpm.
- After adjusting the H screw, turn out the L screw by 1/4 turn. If there is smoke in the exhaust, and the engine goes from low rpm to medium and high with dips, the L screw is unscrewed more.
- Stop adjusting the L screw when the engine runs smoothly from low rpm to high rpm and does not smoke.
Position of the adjusting screws is marked with a red square. To access it, just use a screwdriver. There is no need to disassemble anything.
Idle Speed Adjustment
Idle speed adjustment sequence:
- Start the engine and warm it up for 5-7 min.
- The screw is unscrewed, increasing the RPM until the chain begins to crank.
- Then turn the screw back about 1/4 turn.
If there is an electronic tachometer, its readings should be used for adjustment. Most chainsaws should reach an idle speed of 2500 rpm.
Nuances that arise in the process
Screw L must not be turned too far out with respect to screw H. This leads to a lean fuel/air mixture (less gasoline. more air). With this mix, the piston is dry during operation, gets very hot and can fail.
New carburetors on Chinese chainsaws, sold separately, are factory-adjusted by the standard number of revolutions or arbitrarily. Therefore, they may require adjustment after installation on the chainsaw.