So guys I went riding today and my fourwheeler died and it was not getting spark so we drug it home and once i pulled the plug i knew why it died, the end of the plug was burnt off!!! What could cause this? To lean mix, coil, or cdi issue, need to know asap. my bike is a 1987 TRX350.

So guys I went riding today and my fourwheeler died and it was not getting spark so we drug it home and once i pulled the plug i knew why it died, the end of the plug was burnt off!!! What could cause this? To lean mix, coil, or cdi issue, need to know asap. my bike is a 1987 TRX350.