1. Fuel Delivery: Ensure the fuel is getting to the carburetor properly. Check the fuel lines for any kinks or blockages. Disconnect the fuel line from the carburetor and turn on the petcock. There should be a steady flow of fuel coming through the line. If not, check the fuel tank and make sure the petcock is working properly.
2. Air/Fuel Mixture: Adjust the air/fuel mixture screw on the carburetor. This screw controls the amount of air and fuel that is mixed in the carburetor. If the mixture is too lean (too much air), it will be difficult to start and run. If the mixture is too rich (too much fuel), the engine will flood.
3. Spark Plug Gap: Make sure the spark plug is clean and has the correct gap. Use a feeler gauge to check the gap between the center electrode and the ground electrode. It should be between 0.028 and 0.031 inches.
4. Compression: Test the compression to make sure the cylinders are sealing properly. You can do this by removing the spark plug and inserting a compression tester into the cylinder. Crank the engine over and read the compression gauge. It should be at least 125 psi.
If you have checked all of these things and the engine is still not starting, you may need to take it to a mechanic for further diagnosis.
