Blowby Gas Recycling

Most four-stroke motorcycle engines are fitted with a crankcase breathing system. These systems are required to moderate the pressure within the crankcase and to offset the volume variations caused by the normal movement of the piston(s). It is important to note that modern crankcase breathing systems allow combustion blowby gases to escape from the engine crankcase without getting released into the environment. Without a breather, these gases would otherwise build up pressure inside the motor causing poor performance and engine leaks - a good reason to keep your breather line unobstructed and breather filter clean (if equipped). Blowby gases contain atomized oil, unburnt fuel, water vapor and a host of other things the EPA does not want released into the atmosphere. While there are various systems that reclaim blowby gases, most consist of tubing that runs from the engine into the air cleaner box. In the airbox, these gases merge with fresh air and are recycled back into the engine through the normal intake system.