Everything you need to know about the carburetor
Content
Operation and maintenance must be performed
Before electronic injection and its many possibilities, there was a carburetor with one function: to provide and control the air and fuel mixture. It is a 100% mechanical element (as opposed to injection, which is electronic), directly connected to the gas handle and controlled by a cable.
The operation of the carburetor is not obvious, even if its function is clear: to provide the engine cylinder with an air-gasoline mixture in preparation for an explosion.
Air
The carburetor receives air from an air box. An element where it is calmed down and filtered by an air filter. Hence the interest in an effective and efficient filter, you can see why.
Petrol
Then the "inspired" air is mixed with the essence. The fuel is sprayed in small droplets through a nozzle. The magic mixture is sucked into the combustion chamber when the intake valve is open and the piston is at its lowest point. The principle of the internal combustion engine works ...
Mixture arrival diagram
The carburetor controls the flow of gasoline through a hollow needle called a nozzle. It must be in good condition and, above all, not impede the provision of a constant flow.
Gasoline was previously found in a tank, a tank that has a float that judges and normalizes the amount of gasoline. The gas cable is connected to the carburetor. This allows the butterfly to open, which brings in more or less strong air, more or less quickly during the suction mentioned above. The more air there is, the more compression will be during the explosion caused by the candle. Hence another interest: having spark plugs in good condition and good compression inside the engine. By definition, the engine is sealed, and each "leak" causes more or less serious side effects.
Carburetor per cylinder
There is one carburetor per cylinder, each carburetor has its own settings. Thus, a 4-cylinder engine will have 4 carburetors. This is called the carburetor ramp. Actions on each of them are simultaneous.
Correct dosage of air / gasoline for adjustment
On a carburetor motorcycle, you must control the flow rate and also when the motorcycle is idling. So there is an idle rotor that globally controls the minimum engine speed, and a rotor on each carb that governs richness. Wealth is the amount of air that must be associated with gasoline. This adjustment affects the quality of the blast and therefore the power. Power, you said power? An engine that chokes too badly, an engine that is too rich, gets dirty and does not run optimally. In addition, carburettors run into some problems when the quality or quantity of "open" air varies. This applies, for example, to driving at altitude (where air becomes scarce). The engine runs less well.
This is also a problem in races such as Pike Peaks, where the change in altitude is significant during the race, which requires selection.
Engine element to keep in good condition
As you will understand, the carburetor must be in good condition and well adapted to perform well. Let's just say the carburetor and its peripherals. Thus, we rely on non-cracked, undivided intake pipes that cannot leak to bring in a constant amount of air. There is also a gasoline filter that can usually keep the carburetor from clogging up with impurities. Likewise, cables and moving parts should slide well. Then the internal components of the carburetors should be in good condition. Starting with connections including O-rings found in sealed parts.
The carburetor can also be fitted with a flexible membrane that seals the bushel that should slide. Of course, it should be in good condition too. The carburetor has a float in the tank as well as a needle and nozzle. These needles are used to regulate the flow of air or gasoline, as we just saw. Likewise, any deposit in the carburetor should be avoided. That is why we often talk about cleaning the carburetor with an ultrasonic bath, an operation involving its partial or complete disassembly. It is also necessary to check the correct passage of fluids and air throughout the carburetor body.
There are carburetor repair kits and most complete engine seal kits have many of the seals you need.
Synchrocarburetor
And when all carburettors are clean, it is necessary to check if all cylinders are fed synchronously. This is accomplished through the famous "carbohydrate sync", but this will be the subject of a specific textbook. This synchronization is done at regular intervals on motorcycles (every 12 km) and usually every time the spark plug is changed.
Symptoms of a dirty carburetor
If your motorcycle stops or jolts, or if it seems to have lost power, this could be a symptom of a dirty carburetor. This can be especially the case when the motorcycle has been immobilized for several months in the knowledge that it is recommended to empty the carburettors before transferring.
Sometimes it is enough to use an additive in gasoline to clean the carburetor and this can be an easy solution. But if that's not enough, it is important to disassemble and clean. And that will be the subject of a specific textbook.
Remember
- A clean carb is a motorcycle that turns!
- It is not so much disassembly as it is reassembly, which takes time.
- The more cylinders you have on the engine, the more time it becomes ...
Not to do
- Disassemble the carburetor too much if you are unsure of yourself
