Small Engine Troubleshooting Problems? Ask a Mechanic Now.
What engine?? KohlerTwin? Can you control speed at the governor lever at the carburetor? If not, check the throttle butter fly in the carburetor, it may be loose or broken on the throttle shaft.
If you can control the speed with the governor lever, does the governor have push/pull to it when engine is running? If no feel from the governor, the inner governor parts are broken and have no control.
Here is the SV700 Kohler series service manual,showing the governor and carburetor.