Small Engines (Lawn Mowers, etc.): weed eater engine, centrifugal clutch, gas powered scooter

Question
If my weed eater doesn't have a centrifugal clutch, how does it idle? I am looking for an engine to use on a gas powered scooter and everywhere i look online it says i need an engine with a clutch. But how can a weed eater engine idle if it doesn't have a clutch?

Answer
Donald
In the carburetor there is a built in idle port as you let off the throttle the small plate that allows air in causes less flow there fore just allowing a small amount of fuel to pass tru the idle port. When you start to increase the throttle this causes the engine to speed up and makes the weed eater head spin. This is not a centrifugal clutch type of movement.Now if you are going to use it on a scooter then you would need a clutch on the scooter so when you give it more fuel it will spin the wheels,if you had none and were at a idle the scooter would stall due to the extra weight,if you didn't have one you wouldn't be able to sit in it while it is idling.