Motorcycle Engine Vents

The crankcase ventilation system has been in use for several decades. It optimizes the operation of an internal combustion engine while making it run cleaner for the environment. By minimizing the pressure of blow-by gases, the system prevents motor oil from leaking through the seals and gaskets. It also redirects these rather harmful gases into the air intake, making the air we breathe cleaner. These days, the positive crankcase ventilation (PCV) system is used in virtually all cars and motorcycles equipped with a four-stroke engine. There are numerous configurations of this system, but whichever is installed in your bike, it has to be in working condition.

Unlike the early systems employing something like a simple tube to vent a crankcase, the modern ones use a PCV valve and a breather. Commonly, the effect from the valve is most notable when the throttle is closed, and a vacuum that appears in the intake manifold allows for sucking the blow-by gases back into the cylinders. One more benefit of such a valve is that water and fuel vapors in a warming motor are removed from there without being mixed with oil. Also, the valve protects the motor in case of a backfire.

As for the breather, it vents crankcase pressure out while letting fresh and filtered air in. When the motor is loaded and the throttle is wide open, the breather helps to remove the excess blow-by gases. However, when the piston rings are seriously worn out or just don't seat properly like in some large-bore V-twins, the pressure of these gases becomes high enough for motor oil to appear in the breather and even farther, for example, in the air filter. Actually, most PCV setups have more or less serious issues related to bottom or top breathers, breather gear or reed valves, and similar mechanisms. But whatever your engine design and the way of guiding blow-by gases out, both the breather and PCV valve have to work properly without being clogged. Get the right replacements from our store and make sure your bike operates as it should.