Expansion chambers are mainly used in the motorcycle exhaust systems which use two stroke engines. The main purpose of these expansion chambers is to improve the power and performance of the two stroke engines. By using an expansion chamber one could easily get the power, efficiency and performance of four stroke engines. By using the remaining energy of the combusted exhaust which is deliver out of the cylinder, it delivers the extra amount of power, thus it is a recycling method of utilising the power from remaining power present in the exhaust.
The main components of an expansion chamber mainly consist of blow down section, transfer section and a port blocking section. In a stroke engine when the piston moves down, the fuel exhaust is pushed out due to its own thrust and pressure in to a pipe of constant diameter and the pipe forms the initial portion of the expansion chamber equipped in the exhaust system. This pipe is called the head pipe of the expansion chamber of the motor cycle exhaust system. It is kept of constant diameter because the power present the exhaust is kept constant which is utilised in the end cycle of operation carrying out by the expansion chamber. The transfer section consists of a divergently shaped diffuser. This divergently shaped diffuser is divergent at an angle of six to twelve degrees and allows the motorcycle exhaust gas to expand. This divergent section of the transfer section pushes the exhaust to the port blocking section. The port blocking section is convergent in shape at an angle of about eight to sixty degrees as per the requirements of the motor. Thus this convergent section of the motor cycle exhaust system pushes back the fresh exhaust back into the cylinder just before the compression cycle of the piston at high pressure. This type of exhaust exhaust system also consists of a stinger which is used for controlling the exit of exhaust gas as well as help in improving the pressure of the exhaust gases. The different methods adopted to carry out the construction of expansion chamber are the hand-forming method, hydro-forming method and the stamping method.
Since the head pipe of the expansion chamber of the motor cycle has the fresh and hottest exhaust and the divergent port blocking sections, the expansion chamber ace severe temperature variations as well as sound variations. These factors present in the exhaust system can affect the life and performance of the two stroke engines. This type of exhaust system can even affect the efficiency provided by the two stroke engines equipped in two stroke motorcycles. Because of the large shape and size of the expansion chamber it is usually exposed to stones, rocks, woods and other rigid obstacles present on the ground and surrounding. So in order to keep the expansion chamber of the exhaust system in effective condition regular maintenance and service are required.
Though the use of expansion chambers in the exhaust systems of the two stroke motorcycles has many problems everyone tries to get one in order to get the power of four stroke engines. This type of exhaust system is available at affordable prices in the market which can be easily installed in all types of two stroke engines.