take plug out and check for spark? Put the plug in HT lead and then on your cylinder or earthed metal on bike and see if it is sparking by turning engine over as normal. It should spark constant.
Put a small amount of petrol in plug hole put plug back in hole an try to start it. If it fires ok it may well kick into life. If the bike has been standing a while the carb may be gummed up.
BB
BB, April 2009