WELCOME to the asylum XJHero, sounds like a fuel restriction issue. May be junk in the jets in the carb. Is there a filter in-line that may be clogged? Is the tank clean inside? Maybe pull the petcock and see if the inlet screen is clogged, restricting fuel flow. Check choke assembly to ensure the choke is working properly. Check fuel supply hose(s) from tank to carb for obstruction. Try spraying a little starter fluid in the carb while trying to start. If it fires with an external fuel supply then definitely is a fuel delivery issue. 10 to 1 I suspect clogged jets, especially if it has been siting for a while.
Option 2: check to ensure your engine cut off switch (kill switch) is in the proper position and in working order. You may have to disconnect it and/or straight wire together to eliminate the switch as the problem.
I had this happen to me before, bad switch, and it drove me crazy trying to track down.
Good luck, keep us posted...............
MotoBoss screwed with this post 02-24-2013 at 01:41 PM