How many revolutions makes a chainsaw.

The structure and principle of operation of the carburetor of a modern chainsaw, scheme with a description

The carburetor is the node of the chainsaw, which is responsible for supplying fuel to the engine, the quality of operation of all other mechanisms depends on the correctness of its work, which ultimately affects the performance. In this article we will consider in detail its construction, purpose. Also considered are the main faults and recommendations for troubleshooting.

The carburetor is the main component of gasoline internal combustion engines. This is a device by which gasoline is mixed with air. The result is a combustible mixture that keeps the engine running. It is the basis for the entire work of the chainsaw, because through this node, the fuel is prepared for further entry into the combustion chamber.

Chainsaw carburetors come in diaphragm and float.

When working with chain saws, it is necessary to constantly turn them at a certain angle, so there was a need to create the best option. Engineers have created the diaphragm, a carburetor model that is specially adapted for harsh working conditions. It could work even upside down.

Old models, such as the Druzhba, the Ural could not boast of such an option. The user had to resort to various tricks to turn the saw and still keep it running. Such saws were equipped with a special mechanism that allowed to separately rotate the bar itself, giving it a horizontal or vertical direction.

Chainsaw engine malfunction

Signs of chainsaw engine malfunction:

In certain situations it is better to seek help from professionals and take your saw to an authorized service center. But with some malfunctions you can cope with yourself.

In general, in order to eliminate the cause, you must first correctly identify it, otherwise the entire repair will be tantamount to shooting sparrows with a cannon, and perhaps even shooting at the “imaginary” sparrows, because there may be no breakage.

If you try to start the chainsaw and it does not start and does not make any strange sounds (knocking, grinding), it means that you just start it incorrectly (if you pull the chainsaw on the suction, the engine is flooded with fuel, and after that it is difficult to start it).

How to start a cold engine correctly? 1. Move the lever or switch to the “choke closed” position. 2. If your model is equipped with a priming pump, pump the fuel mixture into the carburetor. 3. Pull the starter grip until there is resistance, then yank vigorously to the amplitude of moving your hand to the side (2-3 times). Don’t try to pull the chain saw out of the starter cord! Saw should start and then stop. 4. If the engine fails to start, put the lever in the half throttle or work position and then try starting the chain saw in that position. Please note: some models have an ignition switch, make sure it is turned on.

What to do if the engine still does not start? First unscrew and examine the spark plug. It happens that when they start the chainsaw in the cold, accidentally fill the combustion chamber with fuel mixture. In this case you should also unscrew the plug, dry the combustion chamber with idle power, clean the plug, and try to start the saw again.

How to check the spark plug? Place the unscrewed spark plug onto the cylinder and pull the starter. Be careful! Do not touch the spark plug with your hands during this procedure! If you see a blue spark then the spark plug is fine. Re-insert the spark plug and try to start the saw again. If it fails again. check the connection of the high-voltage wire with the spark plugs, the coil and the ignition system.

The condition of the spark plug is telling you what’s wrong with the chain saw:

• Dry spark plug. Apparently the fuel mixture is not getting into the cylinder. It is not the spark plug that is the problem, so screw it back on. And check the fuel system.
• Wet, heavily fueled spark plug. The reason for the excessive fuel level is hidden in either a violation of the model’s winding rules or improper carburetor adjustment.
• The spark plug is covered with black soot. This could indicate the use of poor-quality oil (so use only original oil for your saw), a misadjusted carburetor, or an improperly prepared fuel mixture. The spark plug should be washed and well cleaned from sludge with an awl or a needle, wiped with an emery cloth and screwed back in place.

When checking the spark plug, pay attention to the electrode gap (it should be 0.5. 0.65 mm). Worn gasket must be replaced.

Signs of an improperly working carburetor

Improper carburetor operation may be due to clogged inlets and improper adjustment.

Signs of incorrect operation:

Do Adjustments Always Need to be Made

Before tampering with the factory carburetor settings, make sure it’s the carburetor that’s causing the chainsaw to malfunction:

First, make sure there is fuel mixture in the tank of the reluctant saw and that it is flowing into the carburetor.

If the tank is full, check the gas line. Disconnect tube from carburetor and prime. If everything is okay, gasoline will spit out in spits according to the manufacturer’s standards.

Low flow indicates a clogged channel or fuel filter. In this case it is enough to clean the fuel pipe and change the filter.

Malfunctions can be caused by an overfilled chainsaw tank. In this case there will be leakage under the crater cover. If so, check the fuel pipe connection to the carburetor. It is sometimes squeezed out when screwing the cap on an overfilled tank. The engine may not start for this reason.

The quality of the oil-and-gasoline mixture may be the cause of the chainsaw’s poor performance. If you do not drain the oil and gasoline mixture and leave the tool in storage for more than 2 weeks, tarring and polymerization of the components will begin to occur in the tank. This can cause fouling on the piston, rings and cylinder liner. Therefore, always prepare the mixture just before working in the required amount.

If there is nothing wrong with the quality of fuel, the chainsaw engine may not start, from the clogging of the fuel and air filters:

To diagnose the fuel filter, disconnect the gasoline line from the carburetor and prime the carburetor. If there is little or no pressure in the nozzle, disconnect the filter.

Before doing this, empty the tank from the mixture and remove the filter element itself. A clogged replacement cartridge can be cleaned, but it is best to replace it with a new one. When working with the tool in dusty conditions, cleaning should be performed regularly.

Be careful when removing the air cleaner so that dirt that has accumulated during operation does not get into the carburetor: it could be expensive to repair.

After disconnecting the cartridge, thoroughly clean any dirt that may have accumulated and rinse it with detergent. Then dry it and refit it carefully.

Step-by-step Instructions for Adjustment

Adjustment of the carburetor on the Chinese chainsaw, and not only, should always take place in 2 stages:

This is not an easy task, but this approach gives you the best result. Let’s take apart.

Stage 1. Idle

Start the engine and warm it up at medium and low rpm for 3 minutes.

Step 2. RPM at Minimum RPM with the T-screw

Use the screw T to set the minimum rpm so that the chain won’t move on the guide bar. If the engine is smoking heavily it is a sign of too rich mixture and therefore the L screw has to be partially turned back. This increases engine rpm and lowers the smoke level.

Now let’s check the engine good momentum and RPM should be reached quickly, the engine should rev up quickly and should run steadily. If the engine is picking up speed slowly or there is a sag, it means that the mixture is poor and it is necessary to turn the L screw. and the engine speed will decrease. The idle speed is also reduced, therefore it is necessary to partially turn the T-screw and check the revolutions for responsiveness again.

It happens so that it does not work from the first time, so it is necessary to repeat steps 2 and 3 until the engine operation corresponds to the 3 rules described at the beginning of the article.

step 2. maximum power

Adjustment for maximal power is done only after the running-in period and after the idle speed adjustment.

The maximum power is adjusted by turning the H screw. Turning it will either make the fuel mix thinner or richer. If it is partially screwed on. the mixture is leaner. When unscrewing. is enriched. The best screw position is determined experimentally when checking wood sawing. When checking, the following rules should be followed:

• The engine must develop the power, which provides a high sawing performance, with moderate smoke output.
• The engine should show good response and not overheat. It must also reset the revolutions, and the chain must stop at the same time.

Note! Engine overheating is the first sign of a very poor mixture and a large overload of parts. This increases the wear of the cylinder. piston group and as a result can cause complete failure.

We also recommend to read articles about how to adjust the carburetor on the following chainsaws: Carver, Partner 350, Ural 2 Electron, STIHL MS 180,

What to have for adjusting and regulating a chainsaw with your own hands

Every carburetor owner should have the necessary tools to make adjustments to this system. There are three adjustment screws, which are located on the body of the device. They have their own markings:

• L. screw for low speed correction.
• H. screw for high speed adjustment.
• T. performs adjustment of the idle speed, in most cases is used for experiments.

Before adjusting the carburetor, it is necessary to prepare the device:

• The engine is warmed up, that is, it is started about 10 minutes before the repair, and turned off when it starts (see. how to start your chain saw).
• The air filter is checked and washed.
• The chain is stopped by turning the screw T as far as it will go (see “Chain stop”). chain oil).

To make a safe repair, you need to prepare a flat surface, where you can carefully position the device, and the chain is turned in the opposite direction. Need a tachometer. It is used to determine if there is a carburetor malfunction. When turning the screws, the sound should be perfect and absolutely even. If squealing notes are noticed, it means that the mixture is oversaturated.

Description of the process

How to find the carburetor adjustment screws on your Husqvarna chain saw.

An important step is to check the cut-off saw on all the modes after the adjustment, for this it is necessary to let the chainsaw cool down and then start it following the cold start algorithm. If the saw starts normally and idles smoothly, you should check the saw. If during the test you find any deficiencies in the chainsaw power, you need to readjust the screw (H) by unscrewing it and check the thrust of the work.

Loss of traction at the maximum rpm recommended by the engine manufacturer is an indication of a worn cylinder or poor fuel quality. Speaking of fuel, 90% of the problems are fuel related. What kind to use? 92 or 95? How much to store? We answered all these questions in an article about what kind of gasoline to pour into a chainsaw.

We recommend to watch video about how to clean and adjust chain saw carburetor, which author also talks about the detrimental effect of fuel on carburetor components. Here’s how to rebuild your carburetor with inexpensive rebuild kits.

The structure of a chainsaw carburetor

To independently adjust the carburetor chainsaw does not need to be a professional motor technician. However, to learn some aspects of the carburetor operation, concerning the process of preparation of the fuel mixture, you will still have to.

Most chain saws have Chinese-made Walbro carburetors. In their structure they are simple, if not to say primitive. There is a monoblock body of through-type with a through hole. Inside the hole is placed a diffuser. a narrowing of the passage with the fuel injection channel. On the two sides there are flaps: the smaller one is a throttle valve, it regulates the amount of fuel mixture to be supplied to the cylinder. The larger-throttle valve is the air valve, which limits air flow during cold start.

Walbro carburetor design: 1. fuel inlet fitting; 2. diaphragm pump pulse channel; 3. inlet valve; 4. fuel pump diaphragm; 5. outlet valve; 6. filter screen; 7. air damper; 8. throttle valve; 9. fuel channel; 10. no-load adjustment screw; 11. needle; 12. no-load nozzles; 13. control membrane; 14. fuel chamber; 15. main nozzle; 16. diffuser; 17. main adjusting screw

All the magic of fuel preparation takes place in the hidden channels and the diaphragm pump chamber. When the throttle valve is turned, the cross-section of the channel through which fuel is injected into the mixing chamber increases slightly and a larger quantity of fuel is received. The carburetor has two kind of valves: for low and high revs. When the choke position is changed, the fuel flow changes proportionally between the two valves.

The necessity of such a device is that the mixture quality should be different at idling and under load. The channel through which fuel is fed to the mixer at idle rpm is not completely blocked when the engine accelerates, and vice versa. the channel of maximum rpm is slightly blown at idle rpm.

Adjusting a chainsaw carburetor with your own hands

Adjusting your chainsaw’s carburetor ensures that the tool runs efficiently at full power with economical fuel consumption. Adjustment should be performed with a clean fuel filter and air filter. For a large number of carburetors adjustment is carried out by three screws: for maximum and minimum revolutions and adjustment of idle speed.

Use screws H and L to adjust the gasoline/air mixture ratio determined by the carburetor throttle opening. When loosening the screws the mixture is enriched and the revolutions drop accordingly.

The designation H refers to the maximum RPM screw controlling the main jets, L. the minimum RPM screw that controls the idle speed nozzle. The S screw is used to precisely adjust the idle speed. Sometimes, to simplify adjustment, the number of available adjustment screws of a carburetor is reduced.

Tuning of the chainsaw carburetor is divided into two stages. the basic (factory settings), which is performed when the engine is turned off. and final, performed on a running warm engine. For the exact RPM you should refer to the instruction manual of your chain saw. Failure to comply with the manufacturer’s instructions may result in damage to the engine.

turn the maximum H and minimum L revolutions slowly clockwise as far as they go and then turn them back two revolutions

Find the highest idle speed by slowly turning the screw L in different directions. After finding the position of maximum engine revolutions, it is necessary to turn the screw L by 1/4 turn counterclockwise. If the chain still rotates at idle speed, turn the screw T or (S) clockwise until it stops.

Check and Adjust Maximum RPM.

Changing the maximum rpm is done with the H screw. When it is turned in (clockwise rotation) the RPM increases, when it is turned out. decrease. Chainsaw engines have the highest RPM from 11500 rpm. up to 15000 rpm. A higher speed is not provided by the ignition, moreover, it becomes dangerous for the engine. RPM limits can be determined by ignition interruption. If they are reached, turn counter-clockwise the propeller screw H.

If engine operation is not checked for acceleration and maximum rpm then the chainsaw adjustment cannot be considered complete.

When smoothly pulling on the throttle trigger the engine should go from idle to maximum rpm (2800 rpm or more) quickly and surely.up to 11500-15000 rpm depending on the unit). if the RPM is slow and sluggish, the L screw should be turned slowly anticlockwise, but not more than 1/8 of a turn.

After adjusting acceleration and maximum rpm you should check the saw idle speed again. engine should run steadily, the chain should not move. Chainsaw adjustment must be repeated if this condition is not met, but with the exception of the basic adjustment step.

Adjusting the chainsaw carburetor with your own hands

Adjusting the chainsaw carburetor allows the tool to operate efficiently at full throttle while saving fuel. Adjustment should be performed with a clean fuel and air filter. For more carburettors adjustment is made with three screws: for maximum and minimum rpm and idle speed adjustment.

Use the H and L screws to adjust the gasoline/air mixture ratio determined by the carburetor throttle opening. When unscrewing the screws the mixture is enriched and rpm decrease respectively, when tightening the screws the mixture is depleted. the rpm increases.

The designation H refers to the maximum rpm screw that controls the main nozzle, L. the minimum rpm screw that controls the idle speed restrictor. The S screw is used to fine tune the idle speed. Sometimes, to simplify adjustment, the number of available carburetor adjustment screws is reduced.

Setting the carburetor chainsaw is divided into two stages. the basic (factory settings), performed with the engine turned off. and final, carried out with the engine running warm. The exact value of the turning angles should be taken from the instruction manual of the particular chainsaw. If the manufacturer’s instructions are not followed, the engine may be damaged.

The maximum H and minimum L revolutions are adjusted by slowly turning the adjusting screws clockwise as far as they will go and then back about two revolutions

Find the highest possible idle speed by slowly turning the L screw in different directions. After finding the highest engine rpm position, turn the L screw 1/4 turn counterclockwise. If the chain is rotating at idle speed, turn the T or (S) screw counterclockwise until it stops.

Checking and adjusting the maximum speed.

the maximum rotational speed can be adjusted with the screw H. If it is turned in (clockwise rotation), the revolutions increase, if it is turned out. decreases. Chainsaw engines have the highest rotational speed from 11500 rpm. to 15,000 rpm. Higher speeds do not provide ignition and become dangerous for the engine. Limit revolutions can be determined by the ignition interruption. if they are coming in, the screw H is turned slightly anti-clockwise.

If the engine is not tested for acceleration and maximum rpm, the saw adjustment is incomplete.

When the throttle trigger is pulled gently, the engine should be able to rev up quickly and steadily from idle to maximum rpm (2800 rpm and higher).up to 11500-15000 rpm depending on the machine). If revolutions are slow and lag behind, the L screw should be turned slowly counterclockwise, but not more than 1/8 of a turn.

After adjusting the acceleration and maximum rpm check the idle speed again. The engine should run steadily and the chain should not move. The chainsaw adjustment must be repeated if this condition is not met, but with the exception of the basic adjustment step.