how in the world does this fuel vacuum (i think) work??? please help.

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Mar 15, 2021
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i recently swapped engines on my hardknock kikker and am curious about how this fuel vacuum system works as it seems to be connected to the engine. (see attached pics) there seems to be a homemade filter atop the system done by the previous owner. the engine pictured is the original 49cc engine. i am now running a 125cc with no rev limit cdi, a 17t-54t sprocket ratio, i am ordering a 28mm pkw racing carb, and would like to know exactly the physics and function of previously mentioned vacuum system. i understand how a normal fuel vacuum petcock works, why does this one attach to the engine?. fist pic shows vacuum system, the hose that I am pointing at connects to the engine. in the second pic i am holding the hose that attaches to the intake manifold. thanks for any help.


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