Are you getting anything when you try to start it?
If you’ve got a spark then it won’t be a fuse. Only electrical things I can think of that it could be is dodgy spark plug or ignition timing – still think that it is fuel/mixture related though. If you turn it over and give it a squirt of “Easystart” through the intake and it coughs then that will suggest that the electrical side is more then likely OK.
Also if you turn it over (alot) and then take out the spark plug and it is dry that point towards a fuel problem, it is wet then I’d start to look electrically.
just a thought – breather hole in petrol cap isn’t blocked is it?