Hi,
Things to check and replace
Spark Plug
Air filter
Carb. It sounds as though Fuel is not getting to your engine and your carb is blocked or dirty. You also need to check all you cables to your Carb, Throttle and Choke.
If it is a two stroke then you may well also need to clean your Baffle. I am sure these are four stroke though.
If all this seems ok you may well need to check your belt.
BB
August 2009