* Fuel system: Make sure the fuel tank is full and that the fuel line is clear. Check the fuel filter to make sure it is not clogged.
* Air filter: Make sure the air filter is clean and not clogged.
* Spark plug: Make sure the spark plug is clean and properly gapped.
* Carburetor: Check the carburetor to make sure it is clean and properly adjusted.
* Compression: Check the engine's compression to make sure it is within specifications.
If you have checked all of these things and the motor still will not run wide open, you may need to take it to a qualified mechanic for further diagnosis.
