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A motorcycle exhaust system – what is its main purpose?

The exhaust system is one of the most overlooked parts of a motorcycle among the common man. The most common misconception is that exhaust is only sound. Like, I will replace the can, change the sound and okay. In fact, the exhaust system is of great importance for the efficient operation of the engine. That is why she should pay a lot of attention.

I will not tire of repeating that there are no talentless elements in a motorcycle, if this is not a sticker on the tank from the gum, which you did not know where to put it, and then it can cover at first a scratch to the metal. So the exhaust system is a fine-tuned engineering unit.

What is the job of an exhaust system?

  • Removing gases from the engine
  • Improvement of the filling of the engine (as a consequence of the increase in power)
  • Extinguishing the flame from the remnants of the combustible mixture
  • Cooling gases and venting them to the rear of the motorcycle
  • Environmental friendliness
  • Reducing noise

Removing gases and improving the filling of the engine is the first, main and main task of the exhaust system. Few people thoroughly know about this principle, many are too fixated on changing the sound. We remember that engine operation is primarily cyclical. Accordingly, the exhaust system is tied to the same cycle. The waves of gases that constantly circulate in the exhaust pipes have different pressure ranges: high and low.

The development of the pressure distribution inside the exhaust pipe is engaged in science – gas dynamics.

The sequence of ideal operation of the exhaust system:

  • Intake valve opening
  • Formation of a reduced pressure stream, which is directed towards the air filter
  • Towards the end of the branch pipe, the low pressure wave of gases is partially reflected and increased pressure is created.
  • Opening the outlet valve
  • High pressure flow to the end of the exhaust system
  • Reflection of gas flow in the form of low pressure

– Wait, where does the reflection of the stream come from?

Suddenly, in order to cool the gases as quickly as possible inside the exhaust system itself, they, the gases, need to be allowed to expand. For this reason, the exhaust system must have a volume greater, preferably several times, than the volume of the motorcycle cylinder.

Now imagine that you are sharply pouring a bucket of water into a narrow-necked funnel. Water, of course, does not instantly teleport through the neck, so you just splash half of the water on the sides. Roughly the same happens inside the exhaust system, a sharp release of heated gases, which instantly expand, but do not have time to completely leave the cavity of the pipe. Hence, the reflection and retracement of the flow of already reduced pressure. Do you dare?

The pinnacle of engineering that crowns an ideal exhaust system is to calculate the length of the intake tract so that the reflected gases have time to return before the valve opens. Then, according to the laws of great physics, the filling of the cylinder increases, as does the engine power. And in the exhaust system, the moment of the return of the reflected gases, which will have time to return to the new release, help the engine to get rid of the remaining exhaust gases.

If the flow of reflected gas returns to the exhaust valve before it closes, it will push some of the exhaust gases back.

Extinguishing the flame, cooling the gases and leading them to the rear of the motorcycle

The second function of the exhaust system is that it protects the pilot more than the motorcycle. Have you ever tried to start a motorcycle without mufflers? And travel without them? Oh, this hellish flame that turns your motorboats into coal. The motorcycle spews out remnants of the mixture that burns out immediately after being thrown, usually in the “elbow” of the exhaust pipe, but if there are too many residues, a flash of fire can be seen behind the motorcycle.

Hot gases must be cooled, which is what happens in the pipes, and so that soot, smoke and hot air do not interfere with the pilot, the pipes go to the tail section. This is how the required volume of the exhaust system is successfully combined with the required length for the discharge. Ideally, position the ends of the pipes so that gases do not escape onto sensitive parts of the motorcycle. How many newbies scorched trunks or light plastic tuning gadgets, forgetting about the exhaust pipe?

Environmental friendliness

Since we have one planet for all, the level of environmental friendliness has long been a concern of manufacturers and legislators. The newer the motorcycle model, the more sophisticated the exhaust system will be, which has additions in the form of catalysts and filters.

Reducing the noise level

And only at the very tail of this list will there be a beautiful exhaust sound. I do not argue that it is the velvety peals that make you look for the sound source in the traffic, but the pleasant timbre is more an additional accompanying characteristic at the time of development than the goal itself.

The high-pitched exhaust tones make pedestrians grimace. These motorcycles are said to scream or squeal. This is because the high ranges are not as enjoyable as the lowered hooting. Therefore, a huge number of pilots are chasing first of all for a beautiful rumbling exhaust sound, and only then they are surprised to learn that their new product increases engine power.

The exhaust system is very often referred to as the motorcycle breathing method. When the system is faulty, dirty or incorrectly selected, the motorcycle will suffer on the exhaust stroke, possibly starting to choke. On the other hand, a well-tuned exhaust can improve the performance of your motorcycle.

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