1. Check the spark plug. Make sure the spark plug is properly connected and gapped. If the spark plug is fouled, replace it.
2. Check the fuel supply. Make sure the fuel tank is not empty and the fuel line is not kinked. Check the fuel filter to make sure it is not clogged.
3. Check the air filter. Make sure the air filter is clean and not clogged.
4. Check the compression. Make sure the engine has compression. You can do this by removing the spark plug and putting your finger over the hole. If you feel air escaping, then the engine has compression.
5. Check the timing. Make sure the timing is correct. You can do this by using a timing light.
6. Check the electrical system. Make sure the battery is charged and the electrical connections are clean and tight.
7. Check the starter. Make sure the starter is working properly. You can do this by trying to start the engine with the starter solenoid bypassed.
If you have checked all of these things and the engine still will not fire, then you may need to take it to a qualified mechanic for further diagnosis and repair.
