Thursday, August 29, 2013
How Motorcycle Exhausts Cut Off Sound
If you have are in love with your bike, chances are you will be very, very particular about what sort of exhaust pipes you use. The right ones can make your machine look and feel like a million dollar baby or make it a design nightmare.
The motorcycle exhaust pipe has a very definite role to play in the dynamics of a bike. It directs the gases that come out of the combustion chamber, away from the machine and therefore the rider. Where do these gases come from and why is it important that they be directed away?
The combustion engine in a motorcycle creates a series of explosions that propel the bike forward. Since we are talking of explosive combustion, we are talking of noise and exhaust gases. Now if these gases were thrown out straight from the exhaust port, you would have a problem on your hands. The front tyres would gradually melt under the heat and what's more, your machine would sound like a disgruntled missile.
That is why bike manufacturers design the exhaust pipes carefully. These pipes take the emitted gas away from the exhaust port, pass them through what we call a muffler or a silencer and then throw them away behind the bike, away from the rider. By the time the gases pass out of the exhaust, they have already cooled off and there is little chance of any unwanted combustion.
The technology used to silence the explosive gases is simple. The gases flow at a great speed into the motorcycle exhaust pipes, which are narrow. Then they enter the muffler, which has more space. As the gases expand into the body of the muffler, they slow down and lose some of the sound energy. There are perforated baffles in the muffler that reduce the noise further. So, by the time the gases emerge from the motorcycle exhaust pipes, the noise has been cut down to a reasonable level. It is also important to remember that a good exhaust design can increase the usable power generated by your bike's engine.
Typically, motorcycle exhausts are of two kinds: the full exhaust system and the slip-on system. The full exhaust system connects the pipes to the head of the engine while the slip-on exhaust connects them to the opening where the muffler is. The former is ideal for those who run their machine at full throttle over long distance. The slip on exhaust system is usually used for street bikes. This allows a little more a