How to Adjust Chainsaw Turnovers

All Ural chainsaws were equipped with standard KMP-100 carburetors and its modifications with slight modifications. And it was the only carburetor for chainsaws, produced in the USSR. Later, with the advent of the latest and latest in the USSR model Ural 2t Electron, the KMP-100U carburetor began to be used. And he was the only one for chainsaws produced in the USSR, which also stood on Druzhba chain gasoline saws.

how to adjust the speed on a chainsaw

Device and principle of operation

Chainsaw carburetor Ural KMP-100U. membrane type. It does not have a float chamber and a floating float with a needle that shuts off the fuel flow when filling the chamber, as on older carburetors. This gives the advantage that the engine of the Ural 2t chainsaw Electron can work in any position, even upside down. The float carburetor cannot work upside down.

The KMP-100U device is basically the same as all carburetors of two-stroke engines. Its function is to prepare a gasoline-air mixture and supply it to the combustion chamber.

The KMP-100U carburetor system can be considered complex, because it must ensure the operation of the engine in three modes:

  1. Launch.
  2. Idling.
  3. The maximum speed.

For each mode, special channels for the flow of fuel, air and the position of the dampers are involved.

Appearance of the new KMP-100U carburetor used on the Ural 2T Electron chainsaw

When starting a cold engine, the conditions for the formation of a working air-fuel mixture in the combustion chamber are very unfavorable for the following reasons:

  • low crankshaft speed with a manual jerk of the starter, weak compression of the fuel mixture in the combustion chamber;
  • part of the fuel is lost on the walls of the cylinder;
  • low temperature makes ignition difficult.

Therefore, to facilitate start-up, an enriched mixture is required. more gasoline, less air. The air supply damper from the air filter in the cold engine start mode is closed, and the gas supply is increased by pumping (suction) with a primer.

After starting the engine, a vacuum is created in the combustion chamber during the piston stroke, so the fuel mixture from the carburetor begins to be sucked in there. air is required for oxygen and fuel to burn out completely. The choke opens.

When you press the throttle, the throttle opens completely, gas and air come in full flow, the engine runs at full speed.

The flow of gas at this moment is regulated only by a calibrated nozzle hole in the carburetor.

In addition to the position of the air and throttle valves, calibrated nozzle openings, the fuel supply is also regulated by the membrane. When filling the carburetor with gasoline, the membrane presses on the beam with a needle and cuts off the supply of excess fuel from the gas tank to the carburetor.

How to adjust the carburetor on a Ural chainsaw

Adjusting the KMP-100U is simple and accessible to every user. There are two adjusting screws on the carburetor (analogues of the H and L screws on some modern imported chainsaws) to adjust the average and maximum speeds. They are accessible from the outside, you do not need to disassemble the case for adjustment.

2 screws with springs can be seen from above, this is the adjustment screws

Adjustment of the carburetor of the Ural chainsaw is carried out on a warm engine. Initial adjustment should be carried out on a warm, but muffled engine.

  1. Both screws are fully tightened, but without excessive force. The screws have sharp, thin tips that can become deformed if over tightened.
  2. Then the first screw, which is closer to the cylinder, is unscrewed by 1 revolution. The second screw is unscrewed by 0.5 turns.
  3. A chainsaw is turned on, given full speed. In case of a failure of turns, the screws can be unscrewed by another 1/3 or 1/4 turn, listening to the engine and finding the optimal mode.

The exact speed is impossible to know. On each chainsaw, it is individual, depending on the characteristics of the carburetor, the condition of the piston system, fuel quality, outdoor temperature, etc.

For adjustment it is enough to remove the cover, there is no need to remove the carburetor from the chainsaw

Idle speed adjustment

The idle speed of the carburetor on the Ural chainsaw is regulated using a screw located on the gas handle. Its rotation changes the position of the throttle (slightly opens it) and, as a result, the idling parameters change.

It may be necessary to adjust the position of all screws regularly.

This video shows the KMP-100U service, and at the end. a simple and clear adjustment algorithm.

Repair: »basic malfunctions and their elimination

Most often, problems with the fuel supply arise when the tiny openings of the nozzles become clogged and when the membrane-beam pair fails. The brass cross of the rocker arm can bend, or jump out of the landing site and cut off the fuel supply not when needed. A soft membrane can dry out over time, lose elasticity, warp and also incorrectly shut off the fuel supply.

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This is how the new membrane looks (on the right)

There are two ways to clean the nozzle hole:

  1. The carburetor is blown with compressed air from a compressor or pump. The hose for supplying gasoline from the tank is removed, an air hose is put on the fitting and the carburetor is pumped.
  2. If the problem is not solved, it is removed, disassembled, gain access to the nozzles, clean and rinse the entire carburetor of the chainsaw. The jet is cleaned in place or unscrewed (it is planted on the thread).

The soft membrane on old carburetors most often fails after long interruptions in work. It just dries out without gas. Therefore, before starting after a long downtime (a year or six months in the summer in the heat), you need to open the gas tank tap, fill the carburetor of the Ural chainsaw with gas, and do a test run after half an hour.

If the carburetor is several decades old, the membrane material can change its properties simply from time to time.

An unsuitable membrane cannot be repaired; they simply change it.

Lack of tightness

Other problems with the KMP-100U carburetor are loss of tightness. Gaskets between the carburetor and the engine housing, and between the parts of the carburetor, must not suck in air during operation and leak fuel when the engine is stopped.

Gaskets can deteriorate for the same reasons as the membrane, that is, dry, become brittle from time to time.

Remkomplekt for the carburetor of the Ural chainsaw

For KMP-100U carburetors, repair kits are still sold. a set of gaskets, a membrane, in other trim levels there may also be a rocker with a spring to it.

In no case can the spring defining the position of the rocker arm be stretched. The cross-arm of the rocker should lie evenly, strictly parallel to the plane of the carburetor, otherwise the fuel supply will be incorrect.

In Soviet times, when not only chainsaws, but also spare parts for them were in short supply, gaskets were made from sheet paronite.

In the absence of paronite, the pads were made of thick single-layer paper (not cardboard), smeared with oil paint.

Refinement of the carburetor of the Ural chainsaw: we eliminate factory shortcomings

Since the KMP-100 carburetor was the only one produced in the USSR, several million were produced. With such mass and many years of production, the product could not be raw and unfinished. All shortcomings were taken into account, finalized already at the beginning of production, and the factory, structural and technological, KMP-100 and KMP-100U had no shortcomings.

All problems they arise from improper operation (low-quality fuel) or simply from physical wear and tear over time.

The KMP-100U carburetor needs to be improved when the engine from the Ural 2t Electron chainsaw is used for another purpose. For example, like a boat engine.

In this case, not the carburetor itself is subject to alteration, but the idle adjustment system located on the gas handle.

What other carburetors did Ural 2t Electron put on a chainsaw

The Ural 2t Electron chainsaw was often installed, and today carburetors from other two-stroke engines with the following engine parameters are being installed:

  • power 5.5 hp
  • combustion chamber volume 90.4 cc,
  • piston diameter 55 mm.

Sometimes carburetors from significantly more powerful engines were installed. For example, from motorcycles "Minsk", "Sunrise". True, there is a drawback, the flow of the fuel-air mixture increases significantly. It was reduced by adjusting the screws. The engine worked, but the fuel overrun was significant.

With the advent on sale, after 1991, of imported chainsaws and spare parts for them, of similar power, carburetors from them began to be used.

Walbro carburetor for the Ural chainsaw

On a Ural 2t Electron chainsaw, the German carburetor proved itself well from the Stihl MS 660 chainsaw, which is close in power. Its feed of the fuel mixture almost completely corresponds to the Ural 2t Electron engine. Perfect fit is achieved by adjusting the screws. The landing dimensions are also almost identical (between the holes on the carburetor and the studs on the engine). The difference of 1 mm is eliminated by grinding both holes with a file, each 0.5 mm.

Video: How to Adjust Chainsaw Turnovers


It looks like a carburetor Walbro, which is put on a Ural chainsaw

How to put a Chinese carburetor on a Ural chainsaw

The native ZiD plant in Perm no longer produces Ural 2t Electron chainsaws and spare parts for them. On sale there are Chinese-made KMP-100U carburetors worth about 1,500 rubles. They are not always of good quality. And users prefer not to put them, but carburetors from Chinese mopeds.

These are high-quality products that have the following advantages:

  • Designed for a long service life;
  • economical;
  • provide easy engine start.

Progress does not stand still, so modern carburetors far surpass the old KMP-100 in all respects. Carburetors from the following mopeds (scooters) are used:

The carburetors of these mopeds are almost the same, and the engine characteristics are similar to the Ural 2T Electron chainsaw engine.

The landing dimensions of KMP-100U and carburetors differ from Chinese mopeds. Therefore, they are put on chainsaws through an adapter.

In this video you can see how the Ural 2t Electron chainsaw really works with a carburetor from a Chinese moped:

The latest modification of the Ural. 2t chainsaw Electron with a KMP-100U carburetor began to produce more than 30 years ago. She gradually goes down in history. But, it seems, it will not leave soon, due to its high maintainability.

The Ural 2 chainsaw Electron has long established itself as an excellent workhorse with high performance, ease of repair and adequate cost. In fact, the only thing that can happen with this tool in the process of competent operation is the lost carb settings.

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What kind of carburetor is used in the Ural chainsaw

On Ural 2 chainsaws, the Electron is equipped with a KMP-100U carburetor, famous for its reliability and ease of adjustment. The body is completely metal, the jets are calibrated, and the membrane is made of a material resistant to a mixture of gasoline and oil.

For the quick start of the chainsaw under negative temperatures, the carburetor is equipped with a cold start lever. With regard to adjusting the quality and quantity of the fuel mixture, it is the screws that can be independently set in the right position.

How is the carburetor on a Ural chainsaw

The carburetor design cannot be called complex, which is clearly an advantage of the Ural 2 Electron chainsaw. The main nodes responsible for the performance of the carburetor should include:

  1. The float chamber, made in the form of a tank. This element is used to keep the fuel level at an optimal level before mixing with air.
  2. The channels through which the fuel mixture enters. From the float chamber, fuel is initially transported to the nozzle, and then enters the sprayer.
  3. The diffuser, which is a lent tube. With the help of this element, the velocity of the air masses increases to obtain a high-quality fuel mixture.
  4. A special tube resembling an aerodynamic design. This is the main element of the carburetor through which air masses pass. This tube is equipped with a special flap that controls the amount of air supplied.

When the carburetor needs adjustment

All new Ural 2 Electron chainsaws supplied by the manufacturer have already passed the standard carburetor adjustment at the factory. However, for the correct break-in of the tool, it is not out of place to purposefully lower the engine speed, and then fine tune it. This process allows you to achieve the most efficient operation of the engine.

In addition, after a certain period, the carburetor settings of the Ural chainsaw are lost. But this is natural, since various difficulties may arise during operation. Symptoms that indicate the need to adjust the supply and preparation of the fuel mixture include:

  1. Increased gas mileage. This is caused by oversaturation of the fuel mixture with gasoline.
  2. Stalling or non-starting engine. In this case, the reason is an excess of air and a shortage of gasoline.

If everything is in order with the fuel mixture, then the Ural chainsaw carburetor adjustment failure is caused by mechanical reasons:

  1. Strong vibration. The protective cap is damaged over time, as a result of which the adjusting screws randomly move.
  2. Clogging. The use of low-quality fuel, damage to the filter element, the appearance of scale. all this contributes to the appearance of blockages. Without a complete disassembly, cleaning of the entire system and re-configuration, you can not do here.
  3. Piston and cylinder wear. If the problem is the piston part of the engine that has become unusable, then adjusting the carburetor will only help for a while.

Setup algorithm

Calibration of the carburetor saw Ural 2 Electron consists in changing the amount of the fuel mixture and its quality characteristics. There are two types of adjustment.

Idle tuning

Before proceeding with the adjustment, make sure that:

  1. The engine is stable, the chain does not move.
  2. Strong smoke is absent.

The adjustment algorithm is as follows:

  1. The Ural saw engine starts and warms up a bit. Screw No. 3 sets the minimum speed so that the chain remains in place. If the mixture is too rich (strong smoke comes from the exhaust pipe), then screw No. 1 should be slightly screwed. This will reduce smoke and increase speed.
  2. Then you need to return all the settings to the level of minimum and stable speed. This is done by partially unscrewing the screw number 3.
  3. The next step is an engine throttle test. If, after a strong pressure on the throttle lever, the revolutions quickly go up, then everything is done correctly, and screw No. 3 must be firmly fixed in this position.

In case the engine stops working or the revs are gaining speed slowly, screw No. 1 should be slightly unscrewed. In order to increase the speed, screw No. 3 is slightly screwed. After the saw engine, the Ural is repeatedly checked for throttle response.

Maximum power setting

Power adjustment on the Ural 2 chainsaw Electron is carried out only after the break-in period (it is 25 hours) and after setting the idle speed.

The essence of tuning is to deplete or enrich the fuel mixture.

Incomplete screw tightening means more air and less fuel. When the screw is loosened, everything happens the other way around, that is, the combustible mixture is enriched. The most preferred position of the screws can only be determined experimentally.

In the process of tuning the Ural carburetor, you must remember the following principles for the correct operation of a chainsaw:

  1. The engine should always have good cutting performance, and smoke should be moderate.
  2. The engine must always have excellent throttle response. At the same time, in the process of sawing wood, the chain should not stop, the saw overheat, and the engine independently slow down.

In the event that the carburetor is completely misaligned and the engine stops starting, it is recommended to perform the following actions:

  1. The screw number 1 is fully screwed in until it stops, and after it is turned out one turn, no more.
  2. Screw number 2 is screwed to the limit, and then twisted half a turn.

This will allow you to return the adjusting screws to their original position, and then correctly configure the carburetor of the Ural chainsaw according to the standards described above.

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Carburetor repair: video

Despite its high reliability, the carburetor of the Ural 2 chainsaw Electron (KMP-100U) may fail. As a rule, such problems are caused by untimely service and neglect of the tool. On how to correctly identify the cause of the malfunction and fix it yourself, see the video.

Ignition Adjustment: Video

The process of checking for correctly set ignition on Ural chainsaws is quite simple. Especially if you strictly follow this algorithm:

  1. The Ural saw engine starts and warms up for some time.
  2. The owner of the tool is determined with the most persistent turns of the tire, and then reduces engine speed.
  3. The next step is to pull the starter. over, this should be done as sharply as possible.

If the engine is rapidly gaining momentum, then the ignition system is set correctly. If this did not happen, in this video you can see the whole setup process.

The carburetor is an important element of any chainsaw, including the Ural 2 Electron. In many respects, due to the correct setting, the duration of the engine operation and the efficiency of the chain saw as a whole depend.

For their own needs, in terms of logging or some domestic needs, many choose the Ural 2 saw. This unit is currently quite popular. No wonder the manufacturer of these saws produced about 14 million products of this series.

The equipped Ural 2 chainsaw has:

The total mass without starter is 11.7 kg.;

Productivity. 100 sq.cm./sec;

Fuel consumption at maximum power. about 500 ml / hour.

For initial work with a chainsaw, special settings are not required. It is simply necessary to fill fuel according to the factory instructions. And also I must say that the Ural 2 chainsaw carburetor adjustment is not required. At least for normal use.

Carburetor adjustment in Ural 2 electron

However, it may gradually become clear that the operation mode with the saw requires some adjustment so that the fuel mixture is appropriately selected. So that the setting does not cause any difficulties, it is worth taking a screwdriver, a data sheet from the device itself and a few wrenches of appropriate sizes. It is also worth remembering some features of this process:

It is worthwhile to familiarize yourself with the manual for the saw, in which the factory settings should be described;

It is important to regulate the work of the saw strictly in idle mode. Therefore, first start the engine and hold it at idle. After adjusting the screw, bring the engine to a state in which it will independently increase speed. But the chain on the bus should not move;

Further adjustment of the Ural 2 saw is done at medium speeds;

If smoke is detected from the engine, you need to quickly tighten the screw until the smoke stops. If the engine at the same time continues to work normally, it is worth adjusting the possibility of a quick set of speed by the engine when opening the throttle.

Check engine throttle response by setting low revs and abruptly pressing the throttle to the very bottom. If the engine stalls or cannot quickly gain speed, you will have to unscrew the screw a little more.

When all the necessary adjustments have been made, you need to fix the adjusting view using the locknut.

These manipulations should be done to answer the question of how to adjust the engine in this wonderful saw.

Chainsaw ignition Ural 2

This procedure does not require special skills. You just need to do everything according to the scheme:

The engine turns on and just heats up for a while;

The owner of the saw determines for himself the most persistent turns of the tire set;

After that, the saw is moved to a lower speed;

A sharp pull of the starter is made. A sharp increase in engine speed should occur. If the ignition is set correctly, then this will happen.

Knowing such a simple technique, you will not have questions about how to adjust the ignition in this simple saw.

Run-in saw Ural 2

To achieve minimal friction between the nodes in the new saw, she needs to go through a certain process of running in. At this stage, the saw should set various operating modes. We are talking about the alternation of idle mode with different loads. Wherein:

The first hours of operation of the saw must begin with idle, gradually moving to low and medium loads;

A high concentration of lubricant is made in the break-in mixture. approximately 15 to 1;

It is recommended that the break-in process be carried out, during which about 4 full tanks of the device will be consumed.

Chainsaw repair Ural 2

Any tool can fail over time. This is an indisputable fact. It should, however, be noted that the repair of the Ural 2 electron chainsaw basically comes down to working with the engine. Such units in the saw can stall at a certain load, weakly keep idle and so on.

The reason for the saw to stop working immediately after it starts up may be a faulty carburetor. It will have to adjust the jets in order to get the appropriate fuel supply.

When the heated motor stalls, most likely you will have to change the pistons, spark plugs or clean the air filter. I must say that a fully serviceable motor in the saw is simply obliged to work without jerking. If a ringing knock is heard during its operation, this may indicate a malfunctioning cylinder.