Idle speed adjustment on chain saw

How to adjust the carburetor on a chainsaw and properly adjust the idle speed with your own hands

To adjust the carburetor yourself, you need to familiarize yourself with its structure and remember the order of work that is carried out to adjust the parts responsible for the proper functioning of the components of the device and nearby parts. Handle with care the items to adjust the chainsaw system, and determine that the settings you have set are within the maximum allowable values.

Frequent chainsaw malfunctions

Signs of trouble Possible reason How to fix it
Reasons related to fuel supply
1 No fuel in engine (when removing the spark plug, there is compression inside the cylinder, when checking for sparks) No fuel in the tank or blocked faucet Fill the tank with petrol and oil mixture according to the manual
2 The hole in the gasoline tank cap is clogged The hole in the cap needs to be cleaned
Problems with starting the engine
3 The engine doesn’t start, there is fluid in the exhaust system Water in the fuel Completely drain the fuel and pour in a fresh mixture of gasoline and oil. Add ethyl alcohol to the fuel tank and mix. Water and ethanol dissolve with each other, so this can occur if there is very little water in the fuel system
4 Fuel overflow in the cylinder has occurred Remove the spark plug and check if it is dry or wet. If the spark plug is wet, turn off the fuel tap on the cylinder. By pulling the starter rope, clear the cylinder of existing fluid. Clean and dry the spark plug. Replace the spark plug, turn on the fuel tap and start the engine
5 4 Malfunction Remove the spark plug and check for
the ignition system Check for air gap and moisture on the surface. Clean the gap between the electrodes of the spark plug. Warm it up with a blow dryer or gas torch. Check clearance, adjust as recommended by manufacturer.
6 Gasoline does not flow into the cylinder Clogged carburetor jets Perform carburetor cleaning
7 There is air leakage between the carburetor and the intake Replace the gasket and clear the gap
8 The booster pump does not work. Fuel does not flow into the carburetor. Replace the diaphragm in the pump
9 Fuel does not evaporate because of the cold air outside It is difficult to start at 25°C, the fuel evaporates with great difficulty.

Features of the Chinese chainsaw carburetor

Their design and parameters are different, depending on what power and model of chainsaw they are designed for. All of them are almost identical to the original carburetors in design, but not always in quality. Today you can not consider all Chinese products 100% junk. In turn, according to their quality, they can be conditionally divided into three groups:

  • Poor quality. Unsuitable alloys are used, which oxidize, crumble and break. There is no accuracy of fit, the calibrated holes do not correspond to the required sizes, which leads to overconsumption or shortage of fuel in the combustion chamber. Critical parts fail quickly. Plastic parts quickly become rough or softened by gasoline and stop working. Axles and wire rods bend, fastener threads break. These products are the cheapest. They are made in semi-custom factories, on adapted equipment. They are usually nameless and unmarked.
  • Medium quality carburetors. These products are factory assembled. They don’t skimp on alloys, they have in-line production with quality control. These are perfectly serviceable carburetors that can have a lifespan even longer than an entire chainsaw.
  • Quality carburetors. First of all, these are products of world manufacturers whose facilities are located in China. According to the geography they can be considered Chinese, but make them according to the technologies of the company. the owner of the brand, which values its reputation. For example, Japanese Walbro carburetors are produced in China.
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And then there are those Chinese manufacturers that rely on high quality. They invest heavily in a powerful production, register their own brand and work on its reputation.

Adjusting a STIHL 180 carburetor

Chainsaws from the German manufacturer STIHL have always been known for their ease of use and reliability. STIHL is a German brand. Their simple design means they seldom need repair. The only thing to watch out for is the carburetor. The STIHL 180 chain saw is no exception. Poor carburetor performance is often evidenced by floating RPM, sudden stalling, difficulty starting the engine when it is cold, and high smoke emissions. How to properly adjust and tune the carburetor on a chain saw STIHL 180, and we’ll consider in this article.

The STIHL-Chainsaw 180 has become by far the best-selling chainsaw in the world. Low price and reliability make it popular. It requires no special knowledge and is ideal for gardeners who simply need to trim wood. STIHL 180 chain saw with two-stroke gasoline engine.

Tuning tools

Like all servicing tasks, chain saw adjustment requires the right tools for easy and effective interaction with the machine. Luckily, the basic arsenal for such an activity consists of just a slotted screwdriver with a long rod. Applicable to 95% of carburetors, domestic, amateur and professional chainsaws.

The most accurate adjustment is made with a special electronic device that reads the speed of the crankshaft. If you want to get optimal results, it is better to buy a budget tachometer and figure out how to measure the revolutions of a chainsaw with a simple and effective method. This tool will not be much help for experienced users who can tell the difference by the sound of the defects, but for beginner sawyers it will be of great help.

Some manufacturers overly unique their products by equipping them with items with unusual design. For example, adjusting the carburetor of a Husqvarna 135 or Jonsered CS2238 chain saw will require a screwdriver with an extremely unusual shape bit, which you can not get everywhere. This makes it hard to adjust on your own and has to be referred to a specialized service center. service. If your saw’s carburetor has unusual screw heads, but you want to do the adjustment yourself, it is better to order the required tool in advance (can be found on ali and in some online stores).

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How much does a carburetor cost for the STIHL MS 361 chainsaw?

Today there are at least four different carburetors for the STIHL MS 361 chain saw.

They cost from 1600 to 6400 On foreign sites. about 41 dollars.

Huge price range allows assuming that some of them are non-original, counterfeit and low-quality carburetors.

chainsaw carburetor adjustment tunning | chainsaw Repair മലയാളം

Therefore, it is better to buy the original Walbro carburetors and repair kits for them. As a last resort, it is worth looking at the company Zam, they also have good reviews.

Adjusting the chainsaw carburetor with your own hands

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

idle, speed, adjustment, chain

With the H and L screws you adjust the gasoline/air mixture ratio determined by the carburetor throttle opening. When you unscrew the screws, the mixture is enriched and the rpm drops accordingly, when you tighten 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 nozzle. The S screw is used for fine adjustment of idle speed. Sometimes, to simplify adjustment, the number of available carburetor adjustment screws are reduced.

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

The maximum H and minimum L revolutions adjustment screws should be turned slowly clockwise as far as they will go and then turn them back two revolutions

find the highest idle RPM, to do this turn slowly the screw L in different directions. After having found the position of the maximum engine rpm turn the screw L a quarter turn anticlockwise. If the chain is idling then turn the screw T or (S) counterclockwise until it stops.

Checking and adjusting the maximum rpm.

Correct Way To Adjust Or Tune The Carburetor On A Chainsaw

change of the maximum rpm is done by the screw H. When it is turned in (clockwise rotation) the rpm increases, when it is turned out. decreases. Chainsaw engines have the highest rotational speed of 11,500 rpm or more. to 15000 rpm. A higher speed is not provided by the ignition, moreover, it becomes dangerous for the engine. The rpm limit can be determined by the ignition interruption. If they come on, the screw H is turned a little counterclockwise.

Chainsaw Carburetor Adjustment | How to Tune ‘Correctly’. by Craig Kirkman

If the engine has not been checked for acceleration and maximum rpm the adjustment is incomplete.

A smooth squeeze on the throttle trigger should give the engine a solid, fast climb from idle to maximum rpm (2,800rpm and higher).Up to 11500-15000 rpm, depending on the machine). If the RPM is slow and sluggish, turn the L screw slowly counter-clockwise, but not more than 1/8 of a turn.

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

When the chainsaw carburetor needs adjustment?

Here’s a list of the most common times you’ll need to adjust your chainsaw’s carburetor:

  • The engine starts but the chainsaw keeps stalling or it cannot be started at all. The cause may be too much air in the fuel tank.
  • Increased fuel consumption. This can occur due to excessive saturation of the mixture that enters the engine with fuel. In order for the engine to run well, the mixture must be of high quality.
  • The bolts in the carburettor have lost their fixation due to a damaged carburettor housing.
  • Debris in the carburetor. This can happen if the filter is damaged or if low-quality fuel is used. You will need to completely disassemble the carburetor, flush it and readjust it.
  • The engine does not idle or does not develop full power.
idle, speed, adjustment, chain

Important! If the engine runs poorly because the piston is worn, adjusting the carburetor will not work. In addition, along with tuning, it is advisable to clean the carburetor of debris. this will increase the efficiency of the procedure.

Adjustment screws on chainsaw carburetor

There are only three organs for adjusting the carburetor, these are screws shunted by springs, which are designed for a flat screwdriver. In the lower part of the saw is a pair of screws, L on the left and H on the right. A little above this point is the T (or S) screw.

  • The L screw is the valve that regulates the passage of the fuel channel. It is designed for idle speed functioning.
  • Screw H, is the adjustment of the channel flow, the fuel flows through it. It is designed for adjustment of higher revolutions.
  • Screw T, is the throttle adjustment mechanism. It has the function of defining the choke position when the gas pedal lever is fully released.

The design of the first two screws for adjustment is very simple: on their ends there are needles, which are inserted into the spools of variable section (cones). they all have right threads, so screwing the screw clockwise deepens the needle and thus reduces the flow. If you rotate in the opposite direction, the inverse happens.

This method is used to adjust the quality of the fuel mixture in different modes of operation. If you increase the amount of fuel, the gasoline will not have time to burn out and the engine badly starts revolving. When the mixture is lean, revolutions begin to grow and the temperature of the internal combustion engine increases.

It is worth specifying the information that even with the screws fully screwed all the way, the flow of both channels will not be completely blocked, only if there is a blockage.

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