Wonjan Woes !!

[Wolfie]

This I have heard about quite a couple of times. Specialy on those caps that has the litle breather pipe that goes into the neck just below the bars. The pipe kinksor gets blocked by someting and the shite starts. Bike stands for a couple of seconds, probleme gone for a couple of minutes. And has this Puzzled some mechanics !!??!!

[forchetto]

they replaced a vacuum line and boom. fixed.

My Euro spec Qingqi doesn't have anything like a vacuum line anywhere. There's a vacuum take-off stub in the carb manifold adaptor but it's blanked off.
However the parts book shows some sort of anti-smog device that must be fitted to US spec bikes. Was the pipe replaced item 7 in the attached drawing?:

[forchetto]

This I have heard about quite a couple of times. Specialy on those caps that has the litle breather pipe that goes into the neck just below the bars.

I've seen those kind of breather pipes on lots of dirt bikes. Never understood why they're used only on them and not on street bikes.
Our bikes have just a tiny air duct built into the cap that lets air into the tank.

[Luis Carlos]

I've seen those kind of breather pipes on lots of dirt bikes. Never understood why they're used only on them and not on street bikes.
Our bikes have just a tiny air duct built into the cap that lets air into the tank.

hello friends unfortunately not speak English but I want to help
Operation of the system
If there is negative pressure in the exhaust, the reed valve of the air induction system is open and
allows the passage of fresh air, coming from the box of air filter for the exhaust collector.
This process of burning occurs in a range of temperature from approximately 580 to 720 ° C
and significantly changes the volume of hydrocarbons (HC) and carbon monoxide (CO)
turning them into carbon dioxide (CO2) and water (H2O).
This system injects air filter, clean, in the exhaust outlet to help supplement the burning of unburnt gas inside the cylinder.
The working principle is based on the difference in pressure adjustment and the correct mix of
carburetor, which is deliberately impoverished.
This adjustment is made in the factory and should not be changed without the correct use of an analyzer of
gas, unless the regulation of idling through the screw of acceleration.