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A decompression system in a motorcycle engine is designed to reduce the compression pressure inside the cylinder during the starting process. This makes it easier to kick-start or electric-start the engine, especially in situations where the engine has come to a halt at the top of the compression stroke.

During the compression stroke, the piston compresses the air-fuel mixture, creating high pressure and making it difficult to turn the engine over. To alleviate this, a decompression system temporarily opens a valve or releases the pressure to reduce the compression resistance during starting.

There are different types of decompression systems used in motorcycles, such as automatic decompression mechanisms, decompression levers, or decompression switches. Automatic decompression mechanisms are commonly found in modern motorcycles and are typically built into the camshaft or valve train. They work by slightly lifting the exhaust valve during the starting process, allowing a small amount of pressure to escape and making it easier to kick-start or start the engine.

Decompression levers or switches, if present, are manual controls that the rider can engage during the starting process. They are typically located on the handlebars and activate a mechanism that opens the exhaust valve slightly, reducing the compression pressure.

It's worth noting that not all motorcycles have decompression systems, particularly those with electric starters, as the electric starter motor is designed to overcome the compression resistance. Additionally, the presence and operation of decompression systems may vary depending on the specific motorcycle make, model, and year. Therefore, it's always best to consult the owner's manual or contact the manufacturer for accurate information regarding the decompression system in a particular motorcycle.

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