What's the rubber tube on the empty filter for the motorcycle?
Some air filters also have rubber inlets for the purpose of ensuring that the air near the inlet is clean.
Control of emissions, there is an air supply valve, is the vent pipe.
There are some rubber tubes in the air filter:1. connecting the engine box or cylinder head is the waste pipe. The exhaust gas from the engine enters the air filter from the tube. Vapor deposition, steam enters the engine with air.2. the left one is the oil pipe, which collects the deposited oil. Let it go when it's full.
Scooter engine case and even a larger pipe, the ventilation tube.
