Where is the motorcycle crankcase breather pipe located?
2 Answers
The crankcase ventilation system typically consists of two pipes: one installed before the throttle valve and another on the intake manifold. PCV System: To prevent excessive gas from entering the cylinder during engine idle and low-load conditions, which could disrupt the air-fuel ratio, a flow control valve is added. Crankcase ventilation includes natural ventilation and forced ventilation. Modern gasoline engines commonly use forced crankcase ventilation, also known as the PCV system. Natural Ventilation: Natural ventilation involves installing a ventilation pipe on the crankcase, equipped with an air filter. When pressure inside the crankcase increases, gases leaking into the crankcase are expelled through the ventilation pipe.
As a seasoned rider with over a decade of motorcycle experience, I've noticed that on most models, the crankcase breather tube is located at the top or side area of the engine, such as near the crankcase cover. It's typically a small rubber hose that may connect to the air filter box or vent directly to the external environment. The breather tube serves to balance internal crankcase pressure, preventing oil leaks or component damage, as the engine generates heat and exhaust gases during operation. If the tube gets clogged, you might notice oil seeping from seals or even detect a burning smell. On my Yamaha, it's tucked away at the upper right of the engine—an inconspicuous yet vital component. I recommend regularly checking the tube for blockages, cleaning oil buildup with a soft cloth, and avoiding debris like small stones or dirt that could obstruct it. Designs may vary slightly between brands like Honda or Harley, but the breather tube is always near the engine's core area. For precise location details, it's best to consult the vehicle manual or ask a professional mechanic to avoid missing critical details during maintenance.