Akira,
Just a few questions I need to know first:
1. How long have you had the machine?
2. Have you done anything to the carby settings(the 'H'screw and the 'L'screw?
3. On the carby can you see the word Mexico stamped on it (it will be near the screws that go through carby to hold it on)?
4. Is it an old spark plug?
Answer these and I will try to help you.
