Where to hook vacuum lineon might carburetor Jeda 50 cc

Silly question, but are you sure you are getting gas through the line? Could the line from the tank be plugged? How about the tank port?
Is there a fuel shutoff?

just check that you have corectly put all the hoses lines back. May be need to change around the vacum and line frm master cylinder, are the brakes are good, nice and strong-??

Typically there is a vacuum fuel petcock involved. When the motor is turned over a small vacuum line opens the fuel petcock and fills the carburetor with gas. If the vacuum line is not hooked up correctly the fuel will not flow when vacuum is applied. If the petcock is stuck, the fuel will not flow. Also if the carburetor has been sitting with old fuel in it for a while the float needle may be stuck closed stopping fuel flow. Clean the carburetor and inspect the fuel petcock for operation and correct hook up.