Many of you will take this topic as something that is obvious and in general why write about it, but I came across some opinions that, to put it mildly, left me perplexed.
Some time ago, a friend of mine decided to buy her husband a motorcycle (YES !!). However, there was a dilemma – carburetor or injection. The matter for me seemed obvious, but in the company of motorcycle advice I was not the only one. I learned that the carburetor is quite as good as the injection. And it is cleaned only once a year. And it synchronizes even less frequently. Suctioning and warming up the motorcycle is nothing special, after all, and generally it’s exactly the same, just a little different….
In another situation also related to the purchase of a motorcycle, I heard an expert advise a buyer: “A carburetor is a carburetor…”.
From the beginning
The engine in a motorcycle is a heat engine. It converts thermal energy into mechanical energy. More! In a motorcycle we have an engine with internal combustion, and this means that it converts chemical energy into heat, and then with a “small” loss into mechanical energy. In order for combustion to occur, 2 substrates must be supplied – fuel and oxidizer. The fuel in most motorcycles is gasoline, and the oxidant is the oxygen in the atmosphere. We won’t talk about the composition of oxygen in the atmosphere, because we sort of… don’t really have any influence on it. But we can already talk about the amount of fuel.
In spark-ignition engines, the composition of the mixture must be right, because ignition is by means of a spark, and in order for the flame to spread, it must have the right mixture.
If the mixture is too poor or too rich – the engine will not ignite. If the mixture composition is just a little wrong, the engine will ignite, but it will run badly. (I’m leaving aside here treatments in the form of stratified mixture combustion systems, or various other tricks that reduce fuel combustion.)
What is a good mixture?
In theory, the matter seems to be very simple. One should pour 1 kg of gasoline for every 14.7 kg of air. And that’s it. However, this is only a theory, because at different moments of engine operation this ratio should be different. Hydrocarbons do not burn all equally. The first hydrogen groups fall off quickly, but it takes time for the entire single hydrocarbon to react. If our engine is spinning very fast – there is no time for the fuel to burn completely. So you need to inject more of it, so that only the first carbon groups burn, and the underburned hydrocarbons fly off to the catalytic converter, or possibly into the atmosphere to make friends with unicorns. On the other hand, when you want to drive gently and burn little fuel, the mixture can be much poorer than stoichiometric.
On the third hand, when the engine is cold, the mixture needs to be richer because some of the heat is used to warm the engine. On the fourth hand, when we close the gas and the engine is used for brake work, fuel should not be fed at all. On the fifth hand, when the throttle is suddenly opened, the mixture must be enriched so that the engine does not choke, and so on.
Now the most important issue in this topic. Perhaps this is the most important issue in our lives.
Nothing happens by magic. It is in order to organize such a fuel metering mechanism that someone must invent and build it. Envision it, measure it, improve it, and at the very end it must be cheap, easy to manufacture and assemble. Finally, we come to our carburetor. Such a carburetor must just meet all these requirements.
It must allow the engine to start (suction), dispense the amount of fuel well in relation to the RPM (proper jets), mix fuel and air well (again, jets), enrich the mixture at sudden throttle openings (accelerator pumps), shut off the supply at brake operation (shut-off valves), and so on. Can you imagine the mechanical complexity of this device? And on top of that, imagine that this is a mechanical thing that has to withstand the poking of home-grown mechanics, carburetor shots and other such horrible things.
At the very end, all of these components are subject to mechanical fouling and just plain mechanical deterioration. Wear of throttle linkages, damage to rubber seals and associated leaks.
In a word, there are as many things in the carburetor that can break down and cause the engine to run the wrong way as in the rest of the motorcycle.
Against this background comes the injection system.
It consists of an injection pump, an injector, a throttle with a position sensor, a flow meter and an engine shaft position sensor. The rest of the components are not necessary for engine operation, but only support it. I would even add that at full throttle, the engine computer does not listen at all to sensors other than those listed above.
These components, due to their lack of contact with chemical agents, break down extremely rarely. And most often from old age. The engine always runs the same – weather permitting.
The only downside is that with zero current in the battery, we may not be able to start the engine at all.
In addition, mechanical injectors get dirty after many years of use, but they can be cleaned with an ultrasonic cleaner. More – the ultrasonic cleaner cleans gasoline injectors to brand new condition.
Which one is better?
I know that motorcycling is not about making things easy. Or at least not to everyone. I also know that there are people who like their exhaust to fire, the engine to run unevenly, and sometimes you need a little push because you’ve flooded the spark plugs.
Everyone likes their own. Nevertheless, there is no competition in which an injection system is inferior to a carburetor system. A carburetor is a carburetor. And an injection is an injection.)
