Originally Posted by BuRPsa
As I said, it cannot be '360-out' on this bike, it isn't that.
Go check that carb-fitting to the head. I would put thick grease between all mating surfaces and see if it starts... and take it from there. And that bolt/screw on top I'd just glue in (unless you use it for a vacuum pump on a large tank).
BuRPsa, I like the grease check. Super simple and quite obvious. I've always used the spray method which isn't always effective and won't work in a non-running situation, it's going in the bag of tricks
I'd check the flywheel just to eliminate that as a potential problem, like BuRPsa said, can't be 360 off, only goes on one way but if it slipped which it shouldn't with a good woodruff key and proper install it could cause the non-start problem. Probably unlikely but it sounds like you've checked most of the other areas. If it ran already, cam timing should be ok, easy enough to check. I'd be surprised if it was the pickup coil, those usally don't go bad all of a sudden unless there's some physical damage that occurred. A stuck decomp should be obvious with how hard it was to push start when you tried it. I still vote for a good pull
Doesn't eliminate the problem but if it starts the issue will probably be very obvious hearing it run like misfiring (ign), popping back through the carb (fuel/air or decomp) clattering or knocking (mechanical).
It shouldn't need a pull to run but sometimes that can get you on the right track much faster.