Yes you have stale petrol in your carb and blocked jets more than likely.
Easy way to tell take spark plug out and pop a little petrol down bore hole pop in plug and start as normal. If it fires and then dies it will be your carb blocked.
You will need to strip down the carb. Plenty of posts on here of how to do it.
Also change your plug whilst you are at it. And if your elecrtic start isn working then try charging the battery but I suspect you will need a new one after this time.
bb
November 2010