Everyone seems to go right into the carb for solutions.   

Feel like I bring this up a lot, but did you leak-check your engine with 6-10psi air??

You got spark??  If not, check your flywheel key...check wiring...check resistance in stator source coil & pick-up...check resistance in plug coil.

Check your reeds??

If you've got good comp, good reeds, no-air-leaks, no sheared flywheel key, but still no spark ==> it could be like something my first Zilla did to me and it turned out to be a couple things.
#1...I melted the plug coil wire on the head pipe and didn't see it.  Check the resistance/continuity of the plug coil.
#2...Loose or dirty wire connection.  Check everything 3x, especially grounds.  Those 20+ yr old bullet connectors lose there hold over time, and who knows what a prev owner hacked up!  Make sure the plug coil is firmly bolted to some bare/clean steel.

Leave your front fenders and hood off until it's running right -- trust me!  lol