I'd go with checking the plug first, it kind of easier to remove and put back than the carburetor.
The basic troubleshooting process for an engine is Air, Gas, Spark. You have to have all three so check them, the order is up to you and your suspicions but I go easiest/fastest first.
- Gas tank full with good gas;
- Throttle on;
- Ignition key in;
- Check spark plug;
- Check plug is getting electricity;
- Primer working OK;
- Fuel lines;
- Carburetor;
- Compression;
- Stare at it and use mental persuasion;
- Take to shop and pay big bucks to find out what I missed.
Good luck, hope its something in the low numbers and not the highest.
