Motorcycle Repair: throttle cable, 47cc pocket bike, venturi effect

Question
I have a 47cc Pocket bike i bought it off eaby. I don't have any brand information but, it came from a buy it now customer. When i start it up it runs fine but, when i pull the throttle it doesn'tv rev-up or try to take off, it sounds the exact same. I took apart the throttle box and the wire is fine, I also check the carburater and the wire is fine. so I know it isn't the cable. Whats wrong with it and how do i fix it?

Thanks Brant


Answer
Hi Brant.
 I couldn't tell you what is wrong with it until I know what the specifics of the carb are.  Is it a butterfly valve on the carb or is it a needle valve type?

 The needle valve uses a vacuum to actuate a piston with a needle valve to open the port to the float bowl Allowing the fuel to be sucked into the airflow.

 The butterfly valve uses a variable angle air dam which controls airflow past an open fuel port, using venturi effect through the carb body, pulling fuel from the float bowl in that method.

 Are those mechanisms working properly and moving freely and without restriction (tension from the return spring doesn't count)?

 You said that it isn't the cable, so I will presume that you have checked the return and when you release the throttle, it returns to idle setting at the grip.  If it doesn't, then the cable is broken and won't work no matter what the condition of the other components.

Let me know and we can take it from there.
Good luck.
FALCON