When you say it has fuel how are you checking? Wet plug? Smelly exhaust? If you have a decent spark at the plug, and the plug isn't fouled, the bike should run at least, though perhaps crappy if you have failing electrical components. Try a new plug and starting fluid to 99% verify you don't have a fuel/fouling issue.
BTW - the easy way to get starting fluid into the airbox is to put a WD 40 cap with the little red tube on the starter fluid can, pull the air box drain or another vent, and spray it in there. Good trick for lots of bikes.