Mixture quality screw on carburetor

After TURNING the screw to about 10 revolutions, the spark plugs became light brown (dark yellow) in color.

When the screw is turned out, air passes from the pre-throttle space of the first chamber to the bushing - the nozzle of the idle system, located in the pre-throttle space. If the quality screw is screwed in all the way, then the mixture is formed passing the idle jets. The mixture quality screw regulates the supply of ADDITIONAL air to the outlet channel, where the already formed mixture enters.

Of course, the question of increasing the speed when unscrewing the screw is interesting. But personally, I can explain this in such a way that when the screw is opened, due to the vacuum in the throttle space, the air flow accelerates, which in turn causes a higher flow of gasoline through the idle jet. That is, more of the mixture enters the throttle space compared to a fully screwed screw, but the mixture itself is POORER. That is why turnover is growing. Andrey. PS. Why are we already on “YOU” again?

Unfortunately, as established experimentally, at 113 carbs the plant made an UNDOCUMENTED change to the mixture quality control system. At 111, twisting leads to a leaner mixture, and at 113, to a richer mixture.

Economical and stable engine operation in most cases depends on the fuel level in the carburetor float chamber and the idle speed of the crankshaft, as well as on the proper operation of the carburetor.

The carburetor is adjusted to a low crankshaft rotation speed in idle mode with the engine running, warmed up to a temperature of 80-85 degrees Celsius, with the electrical system devices in working order, the timing belt adjusted and the air damper fully open.

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1↑ Topic from PATRIOT 03/25/2013 14:32:03

PATRIOT
Patriot IMZ
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Name: Ilya

From: Krasnodar region, Krasnodar
Registered: 18-02-2011
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Topic: Carburetor adjustment (mixture quality) for beginners!

I think once again it will be useful for beginners to read about adjusting the quality of the mixture, and even the carburetor itself. As already noted, the quality of the mixture at different crankshaft speeds is adjusted differently:

for small ones, use the “quality screw” of the idle speed system;

at medium - with a throttle needle;

at maximum - with the main fuel jet.

Before proceeding with the adjustment, it is necessary to determine the quality of the mixture in various modes by external signs of engine operation. Signs of working on a lean mixture are popping sounds in the carburetor, a drop in power (deterioration of throttle response, drop in maximum speed). Signs of running on a rich mixture are black smoke from the exhaust at maximum speed, popping noises in the muffler, and poor engine response.

In addition, the quality of the mixture can be determined by the color of the spark plug insulator:

with normal mixture quality, the color of the insulator is brown,

with a lean mixture, the color of the insulator is whitish-gray or light brown,

with a rich mixture, the color of the insulator is dark brown or black.

Carburetors are adjusted on a warm engine. If the carburetor is adjusted on a cold engine, then when the engine warms up, it will be disrupted, since the volatility of gasoline in contact with heated parts will change and the quality of the mixture will change accordingly.

The left and right carburetors are adjusted separately. To do this, place the motorcycle on a stand and start the engine (to facilitate starting on two cylinders). On the carburetor cylinder that is not being adjusted, remove the tip from the spark plug and short it to ground. If the tip of the spark plug is not connected to ground, the process of spark formation in a working cylinder will be difficult, especially with discharged batteries. In this case, the engine will operate at an increased speed and the carburetor adjustment will be inaccurate. Next, you need to make sure that there is a gap between the cable sheath and the stop on the carburetor. If there is no gap, ensure it by screwing in the stop.

Then adjust the mixture quality at idle. To do this, you need to unlock the idle quality and quantity screws. Screw the “quality screw” 22 (Fig. 5.4) all the way and use the “quantity screw” to set the minimum stable crankshaft speed. Then slowly turn out the quality screw. In this case, the over-enriched mixture begins to become leaner, but will still be rich. When the mixture composition corresponds to the norm, the rotation speed will increase.

As you further turn out the quality screw, the mixture will become leaner, the rotation speed will not increase, and if the mixture becomes too lean, popping noises will appear in the carburetor, so during the adjustment process, turn the quality screw out until the rotation speed increases. It is difficult to determine from the first time at what position of the quality screw the increase in rotation speed stops, so it is advisable to repeat the adjustment operation 2 - 3 times. Turning out the screw, notice when the increase in rotation speed stops. Having finally established the required position, lock the screw. After adjusting the quality of the mixture at idle using the quantity screw, reduce the engine crankshaft speed to the minimum stable speed. After one carburetor has been adjusted, the second one must be adjusted in the same way. Then, with the engine idling, you must alternately remove the caps from the spark plugs of the left and right cylinders and check by ear whether the crankshaft rotation speeds are the same when operating on the left and right cylinders. If the frequencies are not the same, then you need to use the quantity screw, increasing or decreasing the rotation speed, to restore the balance.

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After adjusting the quality of the mixture at idle, adjust the quality of the mixture at average speed. But first it is necessary to check the quality of the mixture by sharply “opening” the throttle. If at the same time popping sounds appear in the carburetor or “dips” in engine operation (flashes in the cylinder stop; at the same time, if the throttle is “opened” smoothly, the engine gradually picks up speed), then the mixture is lean. If the engine speed begins to increase slowly, the mixture is rich, if quickly, the quality of the mixture is normal.

The quality of the mixture at average speed is regulated by the throttle needle. If the mixture is lean, you need to move the needle lock to a lower groove so that the needle rises. If the mixture is rich, you need to lower the needle, move the lock to a higher groove.

What does the quality screw on the carburetor do?

After TURNING the screw to about 10 revolutions, the spark plugs became light brown (dark yellow) in color.

Adjusting and tuning the carburetor: main steps

Most modern gasoline cars are equipped with fuel injection systems, but before they gained dominance, all cars were equipped with carburetor systems. For this system to work correctly, the carburetor settings must be performed flawlessly. High-quality carburetor adjustment will reduce fuel consumption, make the engine run smoothly at idle, reduce the emission of harmful substances into the atmosphere and increase the overall engine life.

Most domestic cars have a carburetor system, and the question of how to adjust the carburetor will not lose its relevance for a long time. Many owners of rare old foreign cars also face the problem of how to adjust the carburetor. Since the principle of operation of carburetors around the world is no different, the algorithm of work will be the same.

The carburetor is the main component of the fuel system of any carburetor car. This is where air and fuel mix to form a fuel mixture that enters the engine's combustion chambers. A properly adjusted carburetor produces a fuel mixture in the required proportions. Such a mixture will not detonate in the cylinders, which will increase the life of your engine.

How to adjust the carburetor and when to do it

Do-it-yourself carburetor adjustment is done after using low-quality gasoline or when engine operation is no longer stable. For prevention, the manufacturer recommends flushing the carburetor with a special compound every 6-7 thousand kilometers.

Possible malfunctions in the carburetor:

Fuel leaks on the carburetor. In this case, you need to measure the fuel pressure. This is done using a special pressure gauge. The operating instructions will tell you what the pressure should be. Typically it ranges from 0.2 to 0.3 atmospheres. If the pressure is normal, the problem is in the float chamber and the fuel level needs to be adjusted;
Carbon deposits on spark plugs with the smell of gasoline. This clearly indicates a problem with adjusting the carburetor floats or a burnt valve;
Rough engine idling may not only be due to the carburetor. This often happens due to incorrect adjustment of the throttle cable. To check, you need to disconnect the cable and turn the valve manually.

Before you adjust the carburetor correctly, you need to clean it thoroughly. It is recommended to use special liquids for cleaning. The jets cannot be cleaned with toothpicks or needles. Damage to the jets will lead to calibration failure. If the holes cannot be cleaned with aerosols, you can carefully clean them with a soft wire. When cleaning, do not use rags. Threads can clog the holes, which will lead to malfunction of the carburetor. If the aerosol does not remove all contaminants the first time, you need to repeat the procedure.

Setting up the float mechanism

The level of the fuel mixture in the float chamber is directly related to its quality. At an increased level, the mixture will turn out to be lean, which will negatively affect gasoline consumption and increase toxicity. Without adjusting the floats, the question of how to adjust the carburetor cannot be solved. The process of adjusting the floats includes the following operations:

Adjusting the floats in relation to the lid and walls of the fuel chamber. If deformation of the float fixing bracket is noticed, it should be aligned manually;
We adjust the bracket with the needle valve closed;
We adjust with the float retracted and the valve open; the distance between the float and the valve should in this case be set to about 15 millimeters.

Carburetor quality screw VAZ 21083

So this means: the position of the quality screw depends on the fuel level

Does not depend. These are different things.

You already decide whether the level in the carburetor depends on the number of revolutions of the quality screw!

Hello Igor. Although the idle system takes fuel from the float chamber, the quality control almost does not feel this. (Checked with a gas analyzer). But the fuel level is strongly felt in operating modes. And especially at maximum loads. And the quality screw adjusts to XX, when the engine needs very little fuel.

You already decide whether the level in the carburetor depends on the number of revolutions of the quality screw!

The client’s level is 2mm below normal and the screw is unscrewed 9 turns?

But Solex always has a lot to unscrew. I can’t even say how many revolutions I set, because I always set it with a gas analyzer. But it is better to unscrew more than less. If you tighten the quality screw too much, the car will become dull when starting and accelerating at low speeds. But this will not affect consumption, since the XX system does not work in operating modes.

The client’s level is 2mm below normal and the screw is unscrewed 9 turns?

I don’t know, I always focus this way up to five turns, the level is normal, if you open it more, you add it! If it works on a twisted one, then you open it, it definitely overflows!

Try unscrewing the solenoid valve a little and tightening the quality screw. And look at the reaction. Better yet, measure CO. It may even be possible to adjust the mixture to XX, but you will eat a lot.

Setting the fuel mixture supply

The carburetor control screws will help you figure out this setting. Before performing this procedure, you should know that the screws have a plastic factory press-on that limits the rotation of the screws (from 50 to 70 degrees). If turning in this range does not bring results, you need to break the press-on and turn the screws as much as necessary. Before setting the position of the screws, you should warm up the car engine to operating temperature.

To adjust the idle speed of the carburetor, you need to turn out the quantity screw and the mixture quality screw a few turns and, turning them, listen to the operation of the engine. When the engine starts to run smoothly, the carburetor idle adjustment is complete.

Adjusting the idle speed of a car engine with carburetors 2105, 2107 Ozone

Adjusting the idle speed of carburetors 2105, 2107 Ozone and their modifications is one of the most frequently performed operations in carburetor maintenance. As a result, it is necessary to achieve stable engine operation at a crankshaft speed of 850-900 rpm, as well as to normalize the content of CO and CH in the exhaust gases.

Tools required for adjusting XX speed

— tachometer (you can use the one built into the instrument panel) — slotted screwdriver (3 mm) If you don’t have a tachometer, you can adjust the idle speed by ear. But for this you must have at least some experience in car repair, since it is necessary to distinguish when the speed is normal and when it is increased or decreased.

Preparatory work

Before making adjustments, you must first make sure that the ignition timing is set correctly. The distributor cover, breaker contacts, armored wire and spark plugs are in good condition.

If the carburetor is after disassembly and reassembly or you simply need to set the initial value of the adjustment screws, then first tighten them completely, and then turn out the “quality” screw by 2-3 turns, and the “quantity” screw by 3-4.

— Warm up the engine to operating temperature (85-95 0 ). — With the engine stopped, connect the tachometer and start it again.

procedure for connecting an autotester (tachometer)

Adjusting the idle speed of an engine with a carburetor 2105, 2107 Ozone We carry out the adjustment in four stages.

1. Turn the “quality” screw and set the maximum idle speed.

Rotate the screw counterclockwise.

turn the “quality” screw of the fuel mixture of the carburetor 2105, 2107 Ozone counterclockwise, thereby increasing the supply of gasoline to the fuel-air mixture

2. Use the “quantity” screw to set an even higher rotation speed. For example, 80 rpm more. Rotate the screw counterclockwise.

rotate the “amount” screw of the fuel mixture counterclockwise, increasing the total amount of fuel mixture entering the engine cylinders

3. We check with the “quality” screw whether these revolutions are the maximum for the given position of the “quantity” screw.

Simply rotating it back and forth.

We check by rotating the “quality” screw in different directions whether the set idle speed is maximum

If not, then we carry out the above adjustments again.

4. Keeping the position of the “quantity” screw of the fuel mixture unchanged, tighten the “quality” screw so much that the speed drops to 850-900 rpm.

Adjustment in this way is very simple, but at the same time convenient, since it does not require special equipment.

If, after such an adjustment, the content of CO and CH emissions does not correspond to the norm or the idle speed cannot be adjusted, then it is necessary to check:

— whether the fuel and air jets of the main dosing system are dirty; — whether the main fuel jets of the first and second chambers are reversed; — whether the fuel level in the float chamber is increased; — Is the needle valve working? - Is the fuel jet of the idle system clogged; — whether the holder of the fuel jet of the idle system or the solenoid valve has turned away; — whether the tubes have come off the electro-pneumatic valve; — whether the rubber o-ring on the fuel mixture “quality” screw is damaged.

— In some cases, it makes sense to modify the carburetor idle system. See “Modification of the idle system of Solex and Ozone carburetors.”

Five more articles on the site on adjusting and tuning carburetors 2105, 2107 Ozone

Adjusting the carburetor draft

Before you begin adjusting the rods, you should remove the air filter cover so that nothing interferes with the process. First, using a caliper, measure the distance between the rod tips. According to factory parameters, it should be 80 millimeters. To adjust the length of the rods, you need to loosen their clamps.

Checking the strainer should be carried out when there is fuel in the float chamber. This will help you see if the shutoff valve is closing completely. After examining the valve, you need to clean and dry it. Problems with loss of power and engine failures occur due to obstructed fuel supply. This is another reason to thoroughly flush the carburetor.

The tightness of the shut-off needle can be checked using a rubber bulb, while listening for air leaks. If they are present, it is time to change the needle.

How to properly adjust a Solex carburetor

There are still many representatives of VAZ classics driving along the roads. Many of these cars have Solex carburetors under the hood. This carburetor is more economical and is capable of producing a higher quality mixture of fuel and air. For smooth operation of the engine, this carburetor must be properly tuned and adjusted. The class of carburetor masters is gradually dying out, so many people have to do the carburetor adjustments themselves.

How to set the ideal settings yourself

To work, you will need the usual set of tools that are found in almost every garage. To eliminate fuel overflows, you need to correctly set the float in the chamber. This operation can be done using a special template. Experts recommend not using this template, since the number and thickness of gaskets in carburetors do not always match. Fans of various improvements often replace factory gaskets with better ones. It happens that the factory settings of the template do not suit everyone. Although Solex carburetors are the same, the fuel pump can deliver gasoline differently. A lot also depends on whether the return line is plugged, so specialists use a different method.

The mixture quality adjusting screw is tightened by hand until the end;
Next, unscrew it back five turns;
Turn on the engine, remove the choke and use the mixture screw to bring the engine speed to 750 rpm;
By turning the quality screw, we bring the engine speed to the maximum;
Using the quantity screw, reduce the speed to 800 rpm;
We tighten the quality screw a little until instability appears;
We unscrew the same screw back one turn;
We turn the quantity screw until the idle speed reaches 800 rpm (in winter they can be raised to 900).

It is worth remembering that adjusting the carburetor not only eliminates floating engine speeds. A well-tuned carburetor will consume a minimum amount of fuel at stable idle speeds.

Various problems may arise with this adjustment.

It happens that when unscrewing the quantity and quality screws, the engine practically does not react. This happens when a large stream of gasoline flows from the idle hole and the screw is unable to influence it. It is possible that the valve is poorly closed or the jet is deformed. It happens that when replacing jets, they mistakenly choose a larger diameter than required. The plug may be loose. It is worth conducting a thorough inspection of all carburetor elements, this will help avoid such problems. When cleaning, the jets must not be cleaned using abrasives.

If the solenoid valve malfunctions, unscrew it and check for deformation. The mounting hole may also be deformed. If the thread of the mounting hole is torn off, you will have to replace the carburetor cap with a new one. If no defects are found, simply lubricate the O-ring before screwing in the nozzle.

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You can determine whether the carburetor needs adjustment by the engine's response to pressing the gas pedal. An engine receiving a balanced fuel mixture responds to pedal pressure without hesitation, in a split second. The speed should be smooth at idle. There should be no jerks or failures. If the engine runs smoothly at idle, but when you press the accelerator it begins to act up, you need to tighten the quality screw, enriching the mixture.

The quality screw directly affects CO emissions into the atmosphere. Drivers are familiar with the situation when, before going for a scheduled inspection, they need to tighten the quality screw. The emissions become smaller and the car easily passes inspection, after which the position of the quality screw returns to its place. Some people are perplexed why their neighbor’s car consumes less fuel, although both have identical models. It's all about the settings and adjustments of the quality screw.

If the car responds to pressing the gas pedal late, the problem is in the accelerator pump. You can replace it, or change only the spout. When it comes to the spout, the fuel mixture is supplied over-enriched. The problem is solved by replacing the spout. If you decide to install a spout of a different diameter, do not forget to select the appropriate jet for it.

Setting up a carburetor is a rather complicated procedure. Don't expect everything to work out the first time. It may take a couple of weeks to complete the full cycle of eliminating all deficiencies. It is better to listen to the engine, quickly respond to the slightest interruptions in its operation and carry out regular carburetor flushing. The main thing when washing is not to use nameless Chinese-made cleaning products. And if you refuel with high-quality fuel, the carburetor will thank you for years of trouble-free operation.

Adjusting the idle speed of the carburetor on a VAZ-2107

As part of eliminating illiteracy on the basics of adjusting, tuning and repairing carburetors on the VAZ-2107, we are conducting a series of publications focusing on the main nuances and “secrets”, based on the experience of our colleagues from the forum.
So, today we will tell you how to correctly adjust the idle speed on a VAZ-2107 carburetor without having a gas analyzer at hand, but guided only by the tachometer readings. The need for adjustment arises among owners of VAZ classics quite often. Signs - the engine idles unstably, stalls, troits, etc. So, let's go, this procedure is described in simple 6 steps for adjustment. We draw your attention to the location of the quality and quantity screws on the OZONE carburetor for the VAZ-2107

1. We set the nominal crankshaft speed using the mixture quantity screw on the carburetor (for “classics” it is 820-900 rpm).

2. quality screw , we find its position at which the speed will be maximum .

3. the quantity screw , set the speed 15% higher than nominal (for “classics” this will be 950-1035 revolutions/min).

4. We check that the position of the quality screw provides the maximum possible speed for a given position of the quantity screw. If this is not the case, then use the quality screw to achieve the maximum possible speed and use the quantity screw to restore the speed above the nominal speed by 15%. We again check that the position of the quality screw provides the maximum possible speed, and return the speed with the quantity screw to +15% of the nominal value. Etc. until the moment when, at a rotation speed 15% higher than the nominal one, any rotation of the quality screw will only lead to a decrease in speed.

5. By tightening the quality screw, we reduce the speed to nominal.

6. We check and make sure that the car’s engine runs smoothly, without “tripping” at idle and does not stall when the throttle is closed abruptly

Briefly, all this can be stated as follows:

1. Find the position of the quality screw at which the speed will be maximum. 2. If necessary, use the quantity screw to set the speed 15% (130.150 rpm) higher than the required XX speed. 3. see point 1 4. see point 2 5. When it is no longer necessary to adjust the speed with the quantity screw, by turning the quality screw we reduce the speed by 15%, i.e. to the required idle speed.

What to pay attention to:

If the adjustment is made correctly, then when you remove the terminal from the solenoid valve or the vacuum hose from the fitting of the “quantity” adjusting screw housing, the engine should immediately stall.

If, when you tighten the “quality” screw all the way, the engine does not stall, then most likely one of the throttle valves is too open - adjust the locking screws.

Pay attention to the return spring and the “gas” drive. The throttle valve should clearly return to its original position when the gas pedal is released.

For the summer season, the idle speed can be set to 800 - 900 rpm, for the winter it is better to 900 - 1000 rpm. This is due to the fact that in winter the load on the vehicle’s on-board network is usually higher.