The carburetor is a fairly reliable, unpretentious mechanism, which is often used in the design of VAZ cars. Designed to mix fuel with air and then deliver the resulting mixture to the engine itself. The product burns, resulting in an impact on the block valves. Thus, a force appears that ensures the movement of traffic.
For optimal operation of all parts and the motor, the unit needs to be tuned periodically. When thinking about how to adjust the carburetor, it is enough to follow the instructions, observing the basic recommendations.
Main problems with carburetor operation
• The engine is unstable at idle
Let's say if you set the idle speed at 800, drove some distance and the idle speed increased to 1500, then this is a reason to look under the hood and make the correct carburetor adjustment. Perhaps in this case the problem is not in the “carb” itself, but in the wire connecting it and the accelerator pedal, but still, it’s worth a look.
• Spark plugs are constantly dirty and wear out more often
This happens when there is an excessive supply of the combustible mixture, which can occur for two reasons, the first is a burnt-out valve or the second is an incorrect fuel level. If in the first case it is necessary to replace the valve, then in the second case there is a problem with the float, excessive pressure or the float chamber itself.
• Gasoline is leaking
And in this case, the fuel pressure and problems in the float chamber are to blame (the float may be sinking).
Let's sum it up
If you’ve read this far, it means you really want to understand how to set up your motorcycle’s carburetor, and the time spent writing above was not wasted. In fact, tuning the PZ30 carburetor, and others like it, is not the most difficult task and only looks like something incomprehensible. If configured correctly, even the famous Chinese quality will not interfere with the normal operation of the engine, although there will be nuances, such as the need to adjust the idle speed after each cleaning. But if you are patient and take one free evening, then as a reward for your time spent you will receive not only a motorcycle that responds to the throttle and consumes a minimum of fuel with maximum efficiency, but also a longer engine life. Which is, at least, nice, even though the piston engine for most Chinese motorcycles is quite inexpensive.
Having understood the nuances of tuning the PZ30 carburetor, you don’t have to be afraid of other carburetor models; the tuning algorithm, with very rare exceptions, will be absolutely the same.
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Correct carburetor adjustment
A car carburetor is a mechanism that does not require constant intervention in its operation, but twice a year, for prevention, you should pay the necessary attention to setting up this unit, which in turn will improve the operation of your car’s engine and extend its shelf life.
Before we properly adjust the carburetor, let’s understand a little about its structure and purpose.
The carburetor is the heart of a car's fuel system. It prepares the air-fuel mixture for the engine. Correct operation of the machine at idle, at medium speeds and at maximum loads is also the prerogative of this technical unit. Do not forget that starting a completely cold system also depends on the carburetor, because for each engine operating mode, it “prepares” the required fuel mixture in composition, by the way, a lot has been written about cold starting on our prokarbyrator website. ru. Therefore, the question is “How to properly adjust the carburetor?” is quite understandable, because the quality of operation of the engine and the machine as a whole depends on it.
Tools needed
To repair and properly adjust the carburetor, one screwdriver is not enough, as many drivers believe, so you need to make sure you have the necessary tools.
For this you need:
- Screwdrivers of different lengths with different blade sizes. Of course, this is the main tool, but we must remember that you cannot use a screwdriver with rounded edges, this can lead to deformation of the adjusting screw or nozzle. The size of the blade must completely match the slot of the parts being dismantled.
- Open-end spanners. Sizes from 6 to 24 mm.
- Union heads (thin-walled).
- Spark plug keys.
- Pliers.
- Tweezers.
- Air compressor (if purging is planned)
A medical disposable syringe may be useful for cleaning carburetor holes and crimping channels. And also toothpicks to get out small parts (very convenient).
A little about Solex and its design
Carburetors have long been replaced by injection systems. But they are still found in cars driving on Russian roads - in old foreign cars and VAZs produced 20 years ago or more. Before the release of VAZs with injection engines, a number of models were equipped with a Solex carburetor, and interest in it does not dry up.
Adjustment of the Solex carburetor installed on the engine is usually done at a car service center. But, if you wish, you can adjust the device yourself - adjust the quality of the fuel-air mixture (FA) and adjust the Solex float chamber. Solex prepares the fuel assembly and supplies it to the engine in the required volume.
How Solex works:
On a note! The operation of the Solex carburetor uses one diffuser chamber or two - this depends on the operating mode of the car engine.
The main problems in the carburetor and how to eliminate them
Let's give an example of the most common malfunctions in the fuel system of a car that depend on a carburetor malfunction.
• No fuel supply
We unscrew the fuel line from the carburetor and use the manual pumping lever, or, placing a gasoline container under the hose (a small leak is possible), manually turn the crankshaft. If fuel flows, then simply wash the inlet filter; the fuel pump itself is fine. If fuel does not flow, we inspect the pump - there are stains from gasoline, then tighten the housing coupling screws. You can also wash (replace) valves and filters, and, if necessary, the diaphragm.
• No idling
Incorrect engine idling may be caused by the carburetor supplying a lean fuel mixture. This can be determined by ear or by looking into the first chamber of the carburetor; there, droplets of fuel will be visible on the walls. Gradual enrichment of the mixture will lead to stabilization of engine operation.
It is also necessary to check the condition of the solenoid shut-off valve. In the vast majority of cases, it simply flies off the connectors, disrupting the functioning of the motor system. If the carburetor is adjusted correctly, removing the wires from the EMC (solenoid valve) will stop the engine.
• High engine speed at idle
Most likely the throttle valve is faulty. We change the position of the lever relative to the adjusting screw, completely covering the inlet hole in the chamber. For self-adjustment, you need to know that when the gas pedal is fully pressed, the damper must be fully open.
• Difficulty starting a cold engine
The reason most likely lies in the high level of fuel in the carburetor float chamber. Such violations occur when the shut-off valve or float holder is faulty. The level is also affected by the condition of the float itself, which, if necessary, must be checked for leaks by dismantling and lowering into water with a temperature of 80 degrees. Also in this case, you need to check the mesh filter, which is located under the plug.
• Engine does not start
If the problem is in the carburetor, then the cause may be an air damper that does not close completely. To adjust the damper drives yourself, you need to know that when the “choke” handle is fully recessed, it must be open. It should also be mentioned that if the air damper does not open completely, this inevitably leads to an increase in fuel consumption, and it becomes impossible to adjust the idle speed.
Carburetors used on the VAZ-2107, or those whose use is possible
Fundamentally, all these devices can be divided into only two groups.
The former trace their history back to the Weber carburetor modified for the first VAZ cars. This is a structural division of the Italian company Magneti Marelli, which works closely with the FIAT concern. Namely, this is where all the VAZ classics came from. After significant reconstruction, the family received the generic name “Ozone”. They were installed on the VAZ-2107 on the assembly line. The second direction consists of more advanced, yet simple, French Solex devices, produced in Russia by the same factories for the next generations of VAZ cars. The change in the vector of development had an effect, when the first front-wheel drive cars were developed with the participation of German and French companies. As more economical, these carburetors were also adapted to the families of Tolyatti cars with a longitudinal engine. For VAZ-2107 with 1.5 and 1.6 liter model 21053-1107010-20 ; the car will become more economical, although engine output will decrease in some modes. But this is a completely different carburetor; it was not used on production cars, and its adjustment is completely different.
- 2107-1107010 — the carburetor is equipped with a number of parts for working with the electronic forced idle system (EFI). Configured for the operation of a vacuum ignition timing regulator.
- 2107-1107010-10. The same device, but much simpler, does not have a vacuum supply tube to the regulator and is not equipped with a valve and switch for the EPHH system.
- 2107-1107010-20. The most common modification. Controls a vacuum regulator, not intended to work with capricious EPHH.
All these models are structurally very similar, but differ in a number of calibration data; accordingly, the difference in adjustments is mainly numerical in nature.
Carburetor adjustment with screws
First of all, before proceeding with the appropriate adjustment, it is necessary to debug the ignition system, make sure that the spark plugs are in good condition, adjust the fuel supply system, set the permissible gap on the device for automatically interrupting the current circuit, remove the gas pedal rod from the throttle valve and only then proceed to carburetor settings.
The engine must be warmed up to operating condition, otherwise after debugging “cold” during operation it will work completely differently. We completely disconnect the crankcase tube, completely eliminating the influence on the crankcase gas setting. The equipment you will need is a simple slotted screwdriver and preferably a tachometer (digital, since the dial does not show revolutions up to 10 units). In service centers, they could use a gas analyzer as a necessary, but not obligatory, one for fine tuning, but we will make do with the specified accessories.
- We reduce the number of idle speeds to a minimum using the “quantity” screw (the engine is running, but is about to stall).
- Using the “quality” screw, we look for the position at which the number of revolutions is maximum. We begin to screw it in, raising the speed; if the engine stalls, we unscrew it to the required criterion.
- We check the quality of the fuel mixture.
Give the gas sharply - the engine should not stall. If it suddenly stalls, then unscrew the “quality” screw until the engine starts working normally. The setup is complete.
Experienced drivers make such adjustments “by ear” based on the sound of the engine; for “confident” drivers, there are many instructions and training videos; for “beginners”, it is better to carry out the correct carburetor adjustment in the appropriate service centers.
Jets and accelerator pump
A nozzle (injector) is a device for supplying fuel in a certain amount. The engine draws in air through the opening of a large diffuser. At the same time, fuel is dosed through the nozzle. The amount of air sucked in through the diffuser, as well as the amount of gasoline drawn in, depends on the engine displacement. Because of this, on engines with large volumes, carburetors with small jets are installed.
In order for the jet to produce a normal fuel assembly, not lean, it is necessary to find a carburetor that was initially designed for a certain engine volume or as close as possible to it. First, select the fuel and then the air jet. They are selected for the first camera, then the second camera is configured.
The accelerator pump is necessary to supply additional fuel when the throttle is opened, this provides more efficient acceleration. The pump operates through a special cam mechanism. On engines with Solex, you need to install the largest possible cam for the accelerator pump.
Modification of the standard intake manifold
To tune the carburetor system, it is a good idea to equalize the length of the intake channels. To do this, part of the partition is cut off, which separates adjacent channels. This allows you to create a kind of cavity under the carburetor. In this cavity, the working mixture will mix much better, and this will happen without depending on the operating modes and the number of carburetor chambers involved. Only then will this mixture enter the intake channels.
The intake manifold itself must be placed on the cylinder head using pins. This is done so that their relative position is always the same. After installing the pins, it becomes necessary to join the channels in the intake manifold and the cylinder head in such a way that no ledges or other flaws appear at the junction. For best results, use a strip of paper that is thick enough. This paper must be pressed in turn both against the manifold flange and against the mating surface of the cylinder head. There will be prints on the paper corresponding to the channel holes, which can be used to easily identify places where the manifold and the block head do not match.
This method allows you to achieve positive results, which are manifested in improving the acceleration dynamics of a car with a carburetor without increasing fuel consumption. The second advantage is a noticeable expansion of the range of peak torque and maximum power of the internal combustion engine, and their increase is also observed.
How to change the quality of the fuel mixture
It is important that all scooter engines are fueled with a balanced ratio of gasoline to air. A lean mixture causes poor engine performance, reduced power and engine overheating, while a rich mixture causes increased fuel consumption and the formation of carbon deposits.
Adjustment operations are carried out by changing the position of the quality screw and moving the throttle needle.
Rotating the screw clockwise enriches the mixture; turning it counterclockwise makes it lean. The same thing happens with the needle: when the needle is raised, the mixture becomes richer, and when lowered, it becomes poorer. Using both methods together allows you to achieve optimal tuning results. However, not all carburetors have this option, so, as a rule, one of two options is used.
